Pankratz K, Korman J, Emke C, Johnson B, Griffith EH, Gruen ME. Randomized, Placebo-Controlled Prospective Clinical Trial Evaluating the Efficacy of the Assisi Anti-anxiety Device (Calmer Canine) for the Treatment of Canine Separation Anxiety. Front Vet Sci. 2021 Dec 20;8:775092.
The good news is that the study is very well designed, with appropriate controls for many important sources of bias and error. The subjects were selected and randomized appropriately, and everyone was properly blinded. Both a subjective owner measure of effect and objective blinded analysis of video were used to assess effects. There were also active and matched sham devices employed.
As always, there were some limitations to the study. Dogs with behavioral problems other than separation anxiety (SA), such as noise phobia, were excluded. While this makes sense to simplify the study, such problems are common in dogs with SA, so the subjects may not represent the population of SA dogs likely to be treated in the real world.
Dogs were also on varied medications, and none were given a behavior modification program, as would normally be done for this condition, so again how treatment tested might interact with these factors is unclear. The authors also pointed out that some of the study took place during the COVID-19 pandemic, and the activities of owners was likely affected by this event. Finally, there was some missing video due to technical issues, and it is unclear if this might have affected treatment or control dogs differently or otherwise influenced the results.
The authors also mention in the paper that, “after the first 40 dogs completed the study, the devices were sent to the manufacturer for testing; devices that were no longer active were removed from the study and replaced.” They never discuss, however, how many devices malfunctioned and needed replacement, which raises the question of how many dogs may have been “treated” with devices that were not actually operating properly. Presumably, this wasn’t mentioned since it was not a common occurrence, but it would have been useful to include this information.
The less good news is that the results were mixed and inconsistent, yet as is usually the case, they were reported as positive. It is common for research studies that measure multiple outcomes for some to show an effect and others not to. It is often recommended to designate one outcome measure as most important in advance and to use only that to decide if the test treatment works. This avoids the problem of having both successful and unsuccessful outcomes and simply having authors emphasize the positive and de-emphasize the negative.
In this study, the subjective owner assessment showed improvement for all dogs and no difference between treatment and placebo. This is a great illustration of the importance of control groups and placebo treatments in veterinary studies. In this case, the owners were as likely to see improvement with no treatment as with the PEMF device. This was probably due to a combination of caregiver placebo effects and the nonspecific impact of being in a clinical study, where patients get more monitoring and treatment than when they are not in a research trial.
The failure to find any difference in this outcome does not necessarily mean the treatment was not effective, but it does indicate that any benefit it may have had was indistinguishable from placebo to the owners. This is critical since it is mostly the owner perception that determines whether a treatment is thought to be working, and whether treatment is changed or a pet is rehomed or euthanized, in the real world of clinical management of SA.
The more objective analysis of video recordings showed mixed results. In terms of negative behaviors, there was no significant effect of treatment overall, and the comparison between the treatment and sham group was not significantly different at 4 weeks but was different at 6 weeks. The difference from baseline was significant for both groups at week 4 and for only the treatment group at week 6.
In terms of successful treatment, defined as at least a 100% increase in desirable behavior in the video recordings, the treatment group was significantly higher at 4 weeks but not at 6 weeks, and the difference was borderline overall (a p-value of 0.05 is considered statistically significant, and this difference showed a p-value of 0.047).
These results illustrate the problem with multiple outcomes measures and no clear statement before the study of which is primary or what the expectations are. Based on the questionnaire, one could conclude the treatment didn’t work. This is probably not justified since this is a weak measure of effect, but as I mentioned it does signify that the treatment may be no different from placebo in the perception of owners, which is important for how dogs with SA are ultimately managed.
The more objective video assessment showed no overall difference in negative behaviors, which again is consistent with no meaningful treatment effect. There was a difference at 6 weeks, however, and this could be cited to argue that the treatment took time to have a measurable benefit. Unfortunately, this is inconsistent with the results for positive behaviors, which were better for the treatment group at 4 weeks than at 6 weeks, and which again showed a borderline level of statistical significance that could be interpreted as either a real effect or no real difference from chance.
Finally, the importance of consistency across studies and replication cannot be overemphasized. It has become apparent in the last ten years or so that there is a huge problem in biomedical science generally, and in human behavioral science in particular, with replication. Decisions about the causes and treatment of disease are made on a few studies, or even a single study, and then it turns out those results cannot be reproduced, which strongly suggests they were not accurate in the first place.
Veterinary medicine has always suffered from a lack of efforts to replicate research studies, as well as from a lack of good studies in the first place, and this makes it very likely that many of our treatments don’t actually work. All studies should be reproducible before widespread adoption of treatments based on their results occurs, and the mixed results of this particular study make it especially important to show that the findings are repeatable.
Bottom Line This is a well-designed and well-conducted study that shows a mixture of positive and negative results. The most appropriate conclusion would be that the results suggest PEMF might be useful to separation anxiety, but whether or not it is, and how effective it might be, remain to be determined. Given the minimal risks, use of PEMF for this condition is not unreasonable so long as it is not substituted for therapies with better supporting evidence and owners are made aware that the evidence for PEMF is weak and inconclusive.
Only the most dedicated followers of this blog are likely to remember this (are there any?), but way back in 2009, I first wrote about resveratrol in an article about supplements for cognitive dysfunction and brain aging in dogs. My conclusion at that time was:
Resveratrol, in short, stands at the juncture of hope, profit and scientific promise — a social phenomenon galloping ahead of research that is undeniably intriguing but very incomplete.
That was followed by several updates on the status of resveratrol, which still didn’t find scientific justification for the hype.
it is a fine example of both the dangers of excessive and premature commitment to a hypothesis and promotion of products based on it as well as of the ultimately self-correcting nature of the scientific process.
The bottom line here is that we don’t know for certain, but the compound is looking less promising the more we study it.
Since then, I haven’t spent much time checking the evidence base for this compound, but I suspect it is still quite popular, at least based on the fact that it keeps showing up in products, including my wife’s shampoo!
Once I started working in the aging biology field, I found that the story of resveratrol is even more byzantine and disappointing than I had realized. Dr. Brad Stanfield has recently released this video tracing the history of this molecule in the aging field, and it is an excellent example of one of my signature soapbox issues- the dangers of rushing to commercialize a promising but unproven therapy. Sadly, this is still the norm in veterinary medicine, and I am not optimistic we will learn from this example.
One of the most common objections I see to my promotion of science-based treatments is that the scientific evidence supporting them is invalid because it is tainted by some association with Big Pharma, Big Kibble, or some other industry bogeyman. This is a convenient objection to any kind of evidence for science-based medicine or against alternative medicine because it uses elements of truth to make an ultimately invalid argument.
Financial bias is a real thing, and it does impact how we should evaluate scientific research. However, conflicts of interest are a lot more complicated than this, and our understanding and interpretation of them needs to be a lot more sophisticated than “industry funded=bulls$#t” Here is my attempt, from my VPN+ column, to take a more nuanced look at this subject.
A key component of evidence-based medicine (EBM), and of modern life, for that matter, is critical appraisal. This means critically evaluating information before accepting or acting on it. In this time of “alternative facts” and widespread harm caused by acceptance of false or misleading information, the core EBM skill of critical appraisal is more important than ever.
In the context of evidence-based veterinary medicine (EBVM), critical appraisal refers specifically to “a formal, unbiased, systematic approach to assessing the quality and relevance of evidence presented in a paper and its applicability to decision making for our patients.”1
As a clinician, before I decide whether to believe the results or conclusions of a published research study, or utilize them in caring for my patients, I have a responsibility to decide for myself how reliable the results are, how likely they are to represent the truth, and whether they are applicable to my patients.
All too often, vets skim the abstract or discussion section of a paper, find the main conclusion, and then take that on faith and use it to guide their practice. Unfortunately, much of what is published in the scientific literature turns out to be more complicated than it first appears, irrelevant to many patients in the world of primary care, or simply wrong. Critical appraisal is the last line of defense between our patients and unsafe or ineffective treatment based on bad information.
There are many aspects of research publications that must be evaluated in the course of a thorough critical reading. The focus of this column is conflict of interest (COI). This is an issue frequently mentioned in guides to critical appraisal, and often used to dismiss the results of published research, but it is an element of critical appraisal that is especially problematic and for which clear guidelines are not available.
What is a conflict of interest?
Even the definition of a COI is challenging and subject to debate.2–4 I find it useful to define a COI broadly as any personal, institutional, or financial relationship that might influence the beliefs, judgements, or actions of an investigator during the design, conduct, analysis, and reporting of scientific research. This helps to distinguish a COI from mere personal belief, but it goes beyond the common and excessively narrow view of COIs as exclusively about financial interests.
A COI is simply one category of bias that can influence the outcome of scientific research. In ordinary use, the term “bias” has negative connotations as it mostly refers to various forms of prejudice or discrimination against groups of people. However, in the parlance of EBM, “bias” simply means any factor that systematically distorts the results of scientific research away from the truth.
If I flip a coin that is unevenly weighted 100 times and get heads 80 percent of the time that is a type of bias. If a researcher chooses only male dogs to study the effects of a drug, that is a type of bias that can lead to a result consistently different from the true effects of the drug on dogs in general. If a researcher has a particular belief that affects how they choose their hypothesis, design their study, analyze the data, and decide whether or not to publish, that is a type of bias, as well.
It should be clear from this definition and examples that bias is ubiquitous in all research. It is not a sign of bad intentions or incompetence; it is an unavoidable consequence of the operation of the human brain and the imperfection of scientific methods. None of us is without bias if we have any beliefs or distinctive individuality at all. The methods of science exist to help compensate for some of the most common and troublesome sources of bias that arise from the operation of the human brain. This is a pretty uncontroversial view in the fields of EBM and the philosophy of science.
I will also make the potentially more controversial claim, however, that none of us is truly free of any conflict of interest either. Science is a community process, rarely conducted in isolation from other people or institutions, and our relationships inevitably affect our beliefs and practices as scientists. Despite the implications of the word “conflict” in conflict of interest, I believe it is useful to think of a COI as simply a type of bias, and as such, morally neutral in most cases. Just as the term bias lacks pejorative connotations in EBM, the term COI should not be seen as implying malfeasance or bad faith.
Of course, deliberate actions to alter or even fabricate scientific data motivated by financial interests, career considerations, or other types of COI relationships are clearly unethical. However, most COI, like other types of bias that trouble scientific research, involves unconscious and unintentional skewing of research results in a direction influenced by our relationships and beliefs. A researcher can be perfectly honest and genuine in attempting to produce objective, reliable data and still have a COI that influences the results of their research.
What constitutes a COI?
The majority of research into COI and how it influences medical research outcomes focuses on financial COI.2,4 If a researcher stands to benefit financially in some way from a certain study outcome, they are considered to have a COI. This may involve financial gain from the success of a product or service being tested, or the effect of research outcomes on the fortunes of a commercial entity, or other institution the researcher is affiliated with.
The classic example of financial COI is research funded by pharmaceutical companies. It has been pretty consistently demonstrated in human biomedical research industry funding of clinical studies is associated with more favorable study outcomes than is funding by government or nonprofit organizations.3,4 There is limited evidence in veterinary medicine, but it seems likely a similar industry funding bias exists in veterinary clinical trials.5
This relationship is often used to dismiss industry-funded research as hopelessly biased, and to suggest there is deliberate manipulation of all such research for financial gain. Such dismissals, not surprisingly, often come from individuals critical of conventional medical treatments and interested in promoting alternatives. However, it is no more accurate or useful to suggest funding bias is simply fraud or it invalidates all research connected with pharmaceutical or other commercial entities than it is to deny such bias exists at all.
Funding bias is a serious problem, especially given the paucity of noncommercial funding sources for veterinary research. However, it is very rarely the case that it manifests as deliberate fabrication or manipulation of data on the part of iindividuals hoping to improve their financial fortunes. Such deliberate cheating would, perversely, be easier to detect and prevent than the real problem, which is unconscious bias embedded in the perspective of researchers, which influences the questions asked, the design and conduct of studies, and the analysis and reporting of results.
Researchers are typically affiliated with institutions; mostly universities or commercial companies. People tend to gravitate toward institutions populated by like-minded individuals with similar views, and we tend to incorporate the views of our close colleagues or mentors into our own perspectives on scientific questions. Similarly, commercial organizations tend to hire researchers and fund research that aligns with their commercial goals.
For example, a scientist interested in the possibility the anti-inflammatory effects of non-steroidal anti-inflammatory drugs (NSAIDs) might suppress the development of cancer is likely to seek work or funding from companies developing such drugs, not from an herbal medicine company that promotes natural remedies as safer than NSAIDs.
Additionally, a nutritionist concerned about the negative health effects of extruded commercial diets isn’t likely to seek or find support for research seeking to identify such harms from a company selling such diets, and they will likely end up working with like-minded researchers and seeking funding from sources with aligned interests.
Finally, a doctoral student in need of mentoring, funding, and help starting a career is very likely to share many of the views of their academic advisors, at the end of their training at least, even if not at the beginning.
These are all examples of the natural alignment of views that tends to occur when people join together in institutions to participate in scientific research. Funding bias, like other forms of COI, is more likely to be an expression of the shared perspectives of individuals grouped in institutions than simple fraud. This does not, of course, mean it is not a serious problem that skews research results away from the truth. The fact commercial organizations choose what research to conduct or support, and influence the way that research is designed, conducted, and reported, can lead to a body of evidence significantly mistaken or misleading even without any fraudulent intentions or actions.
However, it is worth noting the same type of alignment of views, leading to systematically biased research results, can occur when the alignment is fostered by ideological, political, cultural, and other nonfinancial factors. Research supported by pharmaceutical companies is more likely to be favorable to their products than independently funded studies, but research on homeopathy conducted by homeopaths and published in alternative medicine journals is also much more likely than not to be positive.6,7 Studies of acupuncture conducted in China, where the practice is widely embraced by the populace and the government, are much less likely to report negative results than acupuncture studies from countries where the practice is not part of the shared cultural and political history.8–10
While financial incentives and commercial relationships form an important type of COI, we must recognize the problem of COI is seldom simplistically reducible to deliberate skewing of results in the interest of making money. The ways in which we identify and mitigate COI and incorporate it into our critical appraisal will be different, and more effective, if we take the broader view of COI as involving the influence of personal and institutional relationships on belief and judgement rather than simply following the money.
How does a COI bias research?
When viewed in this larger frame, conflicts of interest can be identified as the potential influences of institutional and personal relationships on research results at every stage of the scientific process. Which questions we choose to ask as scientists and how we go about answering them are related to our context and relationships.
As a general practitioner, for example, I have investigated factors influencing the risk of complications from routine neutering surgeries at my practice because this was a relevant subject for me and my colleagues in a way it likely would not be for an academic surgeon. My study was conducted as a clinical audit, not a randomized controlled trial, because it was part of an in-house quality improvement process at my hospital, not an academic research project. The data collection tools (simple questionnaires) reflected the practical realities and interests of the doctors participating in the study. The examination of how various types of suture material might influence complication rates included only those types of suture we use at our practice, and the neutering techniques compared were those our doctors used, even though there are other materials and techniques we could have considered. These and 100 other choices made during the research project reflected bias associated with my personal and institutional relationships.
One might be tempted to argue this isn’t truly an example of a COI. Given the emphasis on financial incentives in discussions of conflict of interest, one could claim there is not a COI for me to disclose if I publish the results of my study because I don’t have an obvious financial stake in the outcome.
Of course, one could imagine a possible financial or personal incentive. Perhaps clients would stop choosing to have their pets neutered at my practice if we reported a high rate of complications? Perhaps my boss would penalize doctors with higher complication rates, and I might be tempted to adjust my findings depending on my relationship with my colleagues?
However, my point is such narrow personal motives are only a limited subset of the ways in which our personal and professional affiliations influence our scientific research efforts, and excessive focus on these types of influences leads us to overlook other important and relevant factors.
I suspect the types of COI-related bias found in research conducted at commercial and academic institutions resembles this example more than the cliché of shadowy figures in industry deliberately manipulating or hiding data to make their companies’ products look good. I have no doubt that happens, of course, but it is far less common than a subtle, creeping bias introduced by a thousand small choices made in an environment where most people have the same perspective and beliefs.
Regular readers will know, of course, in the last year I have begun working in a biotechnology company developing drugs to extend lifespan and healthspan in dogs. Is this a conflict of interest in terms of writing about COI? Sure! Of course, I work for a company with an exemplary ethical and scientific culture, and I wouldn’t have taken the job if I didn’t believe this to be true. And part of my job there is to be the nagging voice of our collective conscience and push for the best possible science within the constraints of regulations, funding, and the ultimate goal of developing successful clinical therapies. However, my perspective is absolutely influenced by the context in which I work and the ethos of my work community.
I have seen how the regulatory and economic framework of a biotech startup differ from the clinical and academic research contexts. The questions we ask, how we frame them, the studies we design to answer them, and how we handle data collection and analysis are all influenced by this context, just as my research in private practice and the research of any university veterinarian is influenced by those environments and relationships. That is why I rush to disclose this relationship any time I talk or write about any scientific subject.
The interesting and important question, then, is not whether a COI exists for a given research project, since it almost inevitably does, but what do we do about it?
How should COI be considered in critical appraisal?
In the past, a potential COI was largely ignored, with the lofty assumption that because scientists had integrity, their work would not be influenced by such relationships. As I’ve already argued, I believe we are all influenced by our relationships in subtle ways against which good intentions are not an effective defense. This has become difficult enough to deny that it is now more common for a COI to be handled through disclosure. Journals, funding bodies, regulators, and others with some authority over scientific work typically require scientists to disclose any potential COI relationships (e.g. JAVMA,JVIM, JVECC, JAAHA). Such disclosure is voluntary and typically limited to financial COIs, which is problematic, but at least it is easier now to know when such relationships exist.
Sometimes journals take failure to disclose potential COI seriously. The Journal of Veterinary Internal Medicinerecently retracted a paperbecause the authors failed to disclose an obvious financial COI. On the other hand, I wrote last Octoberabout an undisclosed COI that could have potentially significant relevance for interpretation of a narrative review, and in that case the journal chose to largely ignore the omission when it was pointed out by readers.
The difficult question for the critical consumer of science, however, is what to do with information about COIs when it is disclosed. The sad reality is most often disclosed COIs are ignored entirely (if we agree with the conclusions of the research or share the general perspective of the authors, or simply because we don’t believe “good scientists” can be biased11), or used as a pretext to completely discount the results (if we disagree with the conclusions or have a conflicting perspective on the issues).
To again pick on the extreme case of homeopathy, homeopaths accept the shoddiest and most obviously biased studies as probative when they show efficacy for homeopathy, and they reject any research conducted or conducted by science-based investigators or funded by any kind of entity other than a homeopathy manufacturer.6 (Not surprisingly, of course, I have been accused of exhibiting the same type of bias in reverse, which is fair, though I think the record of my public critical appraisal of research studies of all kinds over the years doesn’t support this claim). Sadly, veterinary students who should know better react in a similar way, discounting their potential susceptibility to bias from associations with the pharmaceutical industry.11
Veterinarians who want to read research studies critically are justly confused about how to incorporate CI into their assessment, and there are few resources available to help them12,13. My perspective is a lot of the problem stems from our view of research evidence as binary. We believe a study either proves or disproves the hypothesis it is testing; a drug either works or doesn’t work; a proposed etiology either does or does not cause a disorder. We think the results must be black or white, and we further believe we can make such judgements for every single study independently. These beliefs are mistaken and inconsistent with how science really functions.
A more useful approach to integrating COI into critical appraisal, and into our overall assessment of what is true and false in medicine, is a philosophically Bayesian manner. Though the mathematic details of Bayesian analysis are complex, the underlying principles are straightforward14,15. They suggest that we should assess the reliability of evidence and conclusions in a research study as follows:
Establish a likelihood of the hypothesis or claim being true or false based on what we already known.
Evaluate the data presented and assess all the usual strengths and weaknesses.
Shift our estimate of the likelihood the hypothesis or claim is true to a degree proportional to the strength of the evidence in the paper.
This is really much simpler than even this stripped down description. It just means COI is only one factor in our overall weighting of the evidence in a given study, and each study is only one bit of evidence in our overall assessment of every claim or hypothesis. There is a continuum of confidence in both the study results and their meaning for our beliefs about whatever subject they address, not a binary state of true or false, pure or biased.
When I read a paper on, for example, a new drug, and I see it was funded by the company making the drug, this reduces my confidence in the conclusions slightly (especially if the conclusions are favorable to the company’s interests). However, if the study was conducted by independent researchers insulated from direct influence by company employees, and if the bias control methods are rigorous, that COI has a pretty small impact on my confidence in the study. In contrast, if the study was conducted in a company facility by company employees using subjective outcome measures and with poor methodological control for bias, the COI will significantly undermine my confidence in any positive results.
The details of how we evaluate the significance of potential COI will vary with the specific research project. The important takeaway here is we shouldn’t use COI as a sole reason to accept or reject evidence. We should consider potential COI in light of both the design and conduct of the specific study, and the potential for researcher bias based on the larger context.
A good example is a recent study of the influence of diet during puppyhood on the risk of canine atopic dermatitis (CAD) developing later in life, which appeared in JVIM. I have written a detailed critical appraisal of this study in my regular Veterinary Practice News column, and contributed to a letter to the editor of JVIM detailing various concerns about the paper.
The paper ultimately concludes, with some caveats, feeding raw diets to puppies may protect them against developing CAD as adults. The authors declared no COI. As required by JVIM, they did declare sources of funding. These included both manufacturers of raw diets and Joseph Mercola, an infamous proponent of raw diets and alternative medicine and an anti-vaccine activist repeatedly warned by the Food and Drug Administration (FDA) for promoting COVID-19 misinformation and selling unproven treatments.16,17
The research group, furthermore, has an established history of publishing research promoting raw diets and claiming detrimental health effects from conventional commercial diets. The senior author, an academic researcher with some minor ties to commercial pet food companies, has specifically identified financial COI as a problem in raw diet research, saying, “[raw food is] not really researched in universities. Most universities get sponsored by these big billion-dollar companies, and you don’t really want to step on their toes, I guess. But, I think that’s not really ethical.”18
This is a great example of what I would consider a COI that does not involve direct financial interests or any intentional malfeasance. The researchers have personal and professional affiliations with individuals and institutions committed to the hypothesis raw diets are beneficial and conventional pet foods are harmful. They are undoubtedly experienced and ethical scientists, and they are unlikely to reap any significant financial gains from promoting this idea. Yet, in the context of their history, and the specific work in this study, their affiliations still amount to a COI that must be considered in weighing the reliability of the evidence they provide.
The bottom line
The more interesting I find a subject, the more I write. Not a great habit in today’s TL;DR culture! (That’s “too long, didn’t read.”)
Conflicts of interest are not just about money! All personal, financial, and institutional relationships influence our perspective in ways that can bias the research we do.
Everyone has some type of conflict of interest. Being smart and ethical doesn’t prevent this from influencing the research we do.
Every possible conflict of interest should be reported when we publish scientific research.
Conflict of interest alone does not justify uncritical rejection of scientific evidence.
We should weigh the significance of possible conflicts of interest in the context of the potential for bias to influence study results and the efficacy of bias control methods employed in the study.
No single study ever proves or disproves anything (OK, maybe once in a while, but not often!).
We should assess individual studies and the overall evidence for or against specific ideas in a Bayesian manner, on a continuum of confidence, not with a binary true or false scheme.
Pinchbeck GL, Archer DC. How to critically appraise a paper. Equine Vet Educ. 2020;32(2):104-109.
Johnson C. Conflict of Interest in Scientific Publications: A Historical Review and Update. J Manipulative Physiol Ther. 2010;33(2):81-86.
Mandrioli D, Kearns CE, Bero LA. Relationship between research outcomes and risk of bias, study sponsorship, and author financial conflicts of interest in reviews of the effects of artificially sweetened beverages on weight outcomes: A systematic review of reviews. PLoS One. 2016;11(9).
Institute of Medicine (US) Committee on Conflict of, Interest in Medical Research, Educationand P. Committee on Conflict of Interest in Medical Research, Education, and Practice. Washington, D.C.: National Academies Press (US); 2009. https://www.ncbi.nlm.nih.gov/books/NBK22926/. Accessed January 9, 2022.
Wareham KJ, Hyde RM, Grindlay D, Brennan ML, Dean RS. Sponsorship bias and quality of randomised controlled trials in veterinary medicine. BMC Vet Res. 2017;13(1):234. 9
Cukaci C, Freissmuth M, Mann C, Marti J, Sperl V. Against all odds—the persistent popularity of homeopathy. Wien Klin Wochenschr. 2020;132(9-10):232-242.
Ernst E. A systematic review of systematic reviews of homeopathy. Br J Clin Pharmacol. 2002;54(6):577-582. http://www.ncbi.nlm.nih.gov/pubmed/12492603. Accessed November 12, 2018.
Vickers A, Goyal N, Harland R, Rees R. Do certain countries produce only positive results? A systematic review of controlled trials. Control Clin Trials. 1998;19(2):159-166.
Ma B, Qi G, Lin X, et al. Epidemiology, Quality, and Reporting Characteristics of Systematic Reviews of Acupuncture Interventions Published in Chinese Journals. J Altern Complement Med. 2012;18(9):813-817.
Wang Y, Wang L, Chai Q, Liu J. Positive results in randomized controlled trials on acupuncture published in chinese journals: a systematic literature review. J Altern Complement Med. 2014;20(5):A129. www.liebertpub.com. Accessed November 14, 2018.
Dowers KL, Schoenfeld-Tacher RM, Hellyer PW, Kogan LR. Corporate Influence and Conflicts of Interest: Assessment of Veterinary Medical Curricular Changes and Student Perceptions. J Vet Med Educ. 2015;42(1):1-10.
Lundh A, Boutron I, Stewart L, Hróbjartsson A. What to do with a clinical trial with conflicts of interest. BMJ evidence-based Med. 2020;25(5):157-158.
Resnik DB, Elliott KC. Taking financial relationships into account when assessing research. Account Res. 2013;20(3):184-205.
Homwong N, Hunprasit V, Marthaler D, et al. A Bayesian approach for inductive reasoning to clinical veterinary medicine: The math of experience. J Vet Med Anim Heal. 2015;7(10):308-316.
Gardner IA. The utility of Bayes’ theorem and Bayesian inference in veterinary clinical practice and research. Aust Vet J. 2002;80(12):758-761.
Satija N, Sun L. A major funder of the anti-vaccine movement has made millions selling natural health products. Washington Post. December 20, 2019.
Alliance for Science. FDA warns Mercola: Stop selling fake COVID remedies and cures.
Habib R, Becker K. The Dog Cancer Series: Rethinking the Cancer Epidemic Vol. 1, Chapter 4 (Transcript). 2018:73.
“We must provide an outlet for the creative faculties…And it is this challenge which is recognized by every graduate who turns away from practice, disillusioned by his or her inability to find satisfaction in a situation where…the expectations of training are dashed by the reality of practice. Somehow, we must change the system lest the process of education leads to an increasing number of square pegs looking for a home in a world of round holes…
“We must seek to elevate the status of the practitioner, not only that his position is elevated in the eyes of the academic but, more importantly, in the minds of practitioners themselves. Too often we hear that a practitioner cannot be expected to teach or to research. This is the philosophy of despair.”1
If I’m being honest, the first couple years of veterinary school were a bit tedious. I was a career-change student, about 10 years older than most of my classmates. I had behind me years of struggling to find a career that was meaningful and challenging, yet also economically viable. In that context, being back in school wasn’t such a bad thing. And unlike a lot of my classmates, I hadn’t always dreamed of being a vet, so I didn’t experience the shock of achieving a lifelong dream only to find it was, like reality so often turns out to be, imperfect. However, hours and hours spent memorizing facts, many of which I suspected I would never need again (and I was right!), wasn’t exactly thrilling. I did ok, but I didn’t stand out until I got to clinics.
When I started my clinic rotations, everything came to life for me. The process of clinical reasoning, of collecting and sifting through the information available to find the salient patterns, and then matching that to the tools I had to help my patients, was fascinating and satisfying. Doing medicine was enormously better than learning about it! I may not have been the smartest or most talented in my class, but I turned out to be pretty good at the clinical aspects of veterinary medicine, and my teachers noticed.
One day, an internal medicine resident came up to me while I was studying in a hospital hallway. She wanted to tell me she and some of the other residents and faculty members running the rotation had been talking about me. They had concluded I absolutely had to do a residency because, in her words, “You’re too smart for general practice.”
Of course, my first reaction was an ego-driven flood of dopamine and self-satisfaction. I appreciated the complement, and it reinforced my suspicion I was actually pretty good at this stuff. Alas ,when I had some time to think a bit more about the remark, I started to take a darker view of it.
I haven’t found a definitive source of data, but using numbers from the American Veterinary Medical Association (AVMA) and the Bureau of Labor Statistics, it seems about 20 percent of veterinarians are board-certified specialists. That number was surely lower when I graduated 20 years ago! In this context, one view of the resident’s compliment could be specialty practice is for the best and brightest, and the rest of us have to settle for the less intellectually challenging life of primary care medicine. Being a GP, in this frame, is a consolation prize or a fallback position for the majority of us who don’t make the cut.
By temperament I’m certainly a nerd, and I likely would have pursued a specialty certification (probably in emergency and critical care) and an academic career if that had been possible. However, at the time I graduated, I was 35 years old, I had a six-month-old daughter and a spouse who had indulged my search for a career long enough. I also had $160,000 in loan debt (a pittance by today’s standards, of course, but easily in the top three percent of vet school debt back then). Internship and residency weren’t realistic, and it was time to get a job.
GP life begins
So, did I settle for a lifetime of routine and drudgery? Nothing but vaccines, spays and neuters, and anal glands until I retired? Or maybe, at best, the challenge of entrepreneurship and running a small business? Am I the old guy who hasn’t added a new procedure, drug, or piece of equipment to his toolbox since most new grads were born and doesn’t see why the way we did things in the “good old days” needs to change? Well, not exactly…
I have found many ways to sustain my engagement and enthusiasm with medicine, to challenge myself and grow, both professionally and personally, in my work. Most importantly, I have maintained a commitment to high-quality, evidence-based medicine (EBM), and I have been able to help my patients and clients, and even contribute to the growth of the veterinary profession—all as a lowly GP. So how did I do that?
To start with, when my first practice didn’t meet my expectations for quality of care or opportunities to learn, I started doing relief work at local emergency hospitals to take on more challenging cases. In the absence of a mentor willing and able to teach me, I looked for every opportunity to learn the hard way. It was pretty scary being on alone at night right out of vet school. It wasn’t how I would have chosen to learn, but such a sink-or-swim approach seemed all that was available to vets not destined for internships and residencies in those days.
Once I had a few years in practice, I managed to talk my way into an exceptional hospital, which I have long considered a model of what is possible in general practice. We have been an independent 24/7 practice with up to 30 veterinarians, almost all GPs, and many extremely talented technicians, including some with VTS certification. Management always supported individual veterinarians in pursuing their interests, which allowed me to offer abdominal ultrasound and echocardiography, endoscopy, chemotherapy, and a high-level of surgical and medical care to my patients.
While working in this rich environment, I have constantly striven to “up my game.” I got involved in the Evidence-based Veterinary Medicine Association (EBVMA), helping to lead this organization made up largely of academic veterinarians. I have published and spoken on evidence-based medicine and promoted it to primary practice clinicians around the world.
I have also been lucky enough to have the opportunity to teach veterinary students in practice. Many come to clinics with a wealth of facts crammed into their heads and little idea how to organize and use them effectively to help patients. As much detailed content knowledge as they get from each specialist they train with, many students get very little process knowledge.
Clinical reasoning skills, the ability to take all the knowledge they have ingested over the years, and both organize and use it effectively to make decisions in real time across a broad set of medical domains and patient populations, is something few veterinary students I see have had the chance to think deeply about or practice. This is one area in which the general practitioner is preeminent; the pragmatic evaluation of available information and application of available resources to solve clinical problems within the inevitable constraints of time and money. The broader the range of problems you have to solve and the more limited your tools for solving them, the more efficiently and creatively you have to think!
I have also continued my formal education, completing a master’s degree in epidemiology. Even at this stage (don’t you dare say “venerable!”) of my life and career, I am seizing opportunities to learn and grow. I have shifted to part-time clinical practice so I can take on a role in canine aging biology research. I still do spays and neuters, vaccines ,and anal glands, but that is hardly a fair summary of my career as a GP.
Of course, my path isn’t the right or the only way to make life in primary care practice meaningful and challenging. It is just one example of many possible paths. Yet, I think it belies the notion academic veterinarians all too often inculcate in their students that being a GP is a dead end, a second class of veterinary career.
I still run into this view from time to time. When doing an advanced echocardiography training course, I was chastised for even thinking I should be able to offer this service by the other students (all internists). A few specialists have been offended when I questioned their recommendations, even when I could present clear research evidence to support my concerns, and their position relied entirely on their clinical experience and authority as diplomates. And the medicine resident who encouraged me to pursue specialization so many years ago was not the last to suggest, with the best intentions, my knowledge and abilities were somehow inconsistent with my role as a GP. I doubt I am the only primary care veterinarian to have such experiences.
How to accurately envision general practice
So, how should we think about the role of GP? How should we see ourselves fitting into the profession, and how should students and academics learn to understand our role? What strengths and limitations characterize the general practice role, and how do these complement the academic and other veterinary roles? All of these are deep and hard questions with no simple answers, but I will offer a few thoughts.
Given primary care practice is where the vast majority of patient care happens, our profession has an ethical responsibility to prepare GPs for providing high-quality, evidence-based care. Many of the students I teach and the new graduates I mentor seem to come out of the veterinary educational system with the idea they should handle only minor problems and refer anything challenging.
The definition of what is appropriate for GPs to manage seems to shrink yearly. It’s not just the shock I still sometimes see when I talk about performing an echo or an endoscopy in primary practice. I have had new graduates who felt it was inappropriate to interpret a radiograph or diagnose a mast cell tumor on cytology without specialist input. The message they often seem to get from their teachers (nearly always academic specialists) is that if a specialist can do something then a GP shouldn’t do it.
Of course, this extreme view is not consistent with practical and economic reality. The obvious problem of insufficient specialty capacity and the inability of many pet owners to afford the cost of specialty care is an obvious flaw in this model. However, I believe there are other flaws to this view that are more grave.
One is that such “dumbing down” of general practice to routine wellness care and management of only minor health problems diminishes the quality of care patients receive. It creates a self-fulfilling prophecy. If we teach veterinary students that talent, intelligence, and ambition can only be satisfied in specialty practice, then people with those attributes will eschew general practice. If we don’t teach GPs that they should be practicing high-quality, EBVM because only specialists can do that, then it will become true.
Another problem with primary practitioners gradually ceding diagnosis and treatment of serious problems to specialists should be abundantly clear from even a casual glance at the human healthcare system. The hyperspecialization of human medicine has led to absurdities.
I once started explaining the nature and management of a cranial cruciate ligament rupture to a client when he stopped me with a chuckle. He was an orthopedic surgeon. After four years of undergraduate education, four years of medical school, an internship, and more than one residency, his entire career consisted of six procedures on the human knee. A brilliant, and arguably overeducated man, had been reduced to a highly paid, very specialized carpenter.
Is this the model we wish veterinary medicine to follow? Laying aside the economic realities that would impede full adoption of the hyperspecialization, is this even a model we should aspire to? I would argue it is not, yet that is the direction we would head in if the lessons many of my students and new graduates take away from their training were implemented.
Advantages GPs possess
The strengths of the primary care practitioner are many. We have a holistic view of the patient throughout the lifecycle that is usually unavailable to the specialist. While our knowledge base is inevitably shallower than those in specialty practice, it is broader, allowing us to integrate multiple medical conditions, husbandry, and other owner variables, individual temperament, life stage, and many other factors into the management of specific healthcare problems. I would argue this approach typically allows for better overall patient care, especially when cases are complex with multiple concurrent morbidities.
GPs are also consummate problem solvers, accustomed to making do with limited information and resources. If this ability is not only honed by experience, but strengthened by the application of evidence-based medicine techniques and training in clinical reasoning, it becomes a powerful tool. Specialists are undoubtedly knowledgeable, talented, and creative thinkers, but depth of expertise comes at a price; the loss of a broad perspective and a tendency to follow familiar patterns within a domain even if elements of the context outside of that domain might suggest a different approach.
Finally, there is the obvious issue of accessibility and affordability I have already mentioned. Too many companion animals already go without care because their owners cannot afford it.2 Increasing the reliance on specialists without a fundamental shift in the economic model of veterinary medicine will simply make care less available to more patients.
Apart from the benefits to patients and clients in supporting high-quality care in general practice, encouraging GPs to value themselves and their work, and to stretch themselves professionally, is important to maintaining a talented and satisfied veterinary workforce. We all know our profession is struggling right now, with vets bearing the stacked burdens of high workloads, huge debt, and the many physical and emotional challenges of the job. Constraining people to smaller, and smaller boxes, as GPs or as specialists, is just creating more round holes for Dr. Rossdale’s square pegs. Channeling the most ambitious and talented students into specialty practice or academia, and denying those who do go into general practice the opportunity to fully engage their intellect and creativity in their work can only exacerbate the problems our profession is facing with burnout and job dissatisfaction.
How, then, can we encourage all of our students and new veterinarians to maximize their potential, provide the best possible care for our patients, and avoid the pitfalls of hyperspecialization that bedevil our colleagues in human medicine? As I have already implied, I think evidence-based medicine is a key part of the answer!
Teaching all veterinarians, regardless of their eventual area of practice, to practice EBM would be a good start. While some effort to do this is already part of the curriculum, I cannot say most of the students or new graduates I see have really absorbed the core concepts of critical thinking and reasoning that underlie EBM. We are still emphasizing memorization and regurgitation of facts over rational, effective reasoning strategies.
My students are better able to search the literature and use electronic information tools than my generation, but they don’t often seem to understand what these tools are for. They still seem to rely primarily on authority and the dicta of their mentors for guidance rather than using the information they have learned to support critical reasoning. When I question the rationale for a particular treatment choice, all too often the response is still, “That’s what Dr. X said to do.”
Teaching veterinarians to think critically and independently, and to rely on critical appraisal of controlled evidence when possible, can only improve the quality of clinical reasoning and patient care. It also has the advantages of strengthening one’s confidence in one’s recommendations and practices, and reducing the tendency to defer to academics or specialists, which drives a lot of the relinquishing of cases and problems that could appropriately be retained in the general practice setting.
EBM also helps to delineate the role of generalist and specialists. In areas where there is strong evidence to guide diagnosis, prognosis, and management, there is less need for the deep and narrow knowledge and experience of the specialist. Conversely, when a problem is uncommon or not well understood, and there is little reliable evidence concerning it, a specialist’s strengths become critical.
As an example, the vast majority of the heart disease cases I see in practice are myxomatous mitral valve disease (MMVD). This is a relatively well-understood condition with clear diagnostic and staging criteria, and strong consensus guidelines available to inform treatment. I use echocardiography to support my management of MMVD cases. In my career, I have done a few over 1,000 echocardiograms, and about 85 percent of these have been MMVD cases. There is no reason why the greater expertise and experience of a cardiologist should be necessary to diagnose, stage, and manage this condition in most patients with typical presentations.
My use of this tool fits well into the role and competency of the general practitioner. And the skills I have developed evaluating MMVD patients have helped me utilize the tool in other ways that improve patient care. I don’t need to call in a cardiologist to identify a right atrial mass prior to subjecting a patient with hemangiosarcoma to a splenectomy. I can identify and manage pericardial effusion without the delay of waiting for a specialist or transferring the case. All of these are reasonable and natural elements to primary care.
On the other hand, there are absolutely cardiac cases that fall outside my competency that I should, and do, refer. I don’t ultrasound young animals with murmurs because many will have uncommon congenital anomalies I am not qualified to identify or manage. And whenever there is a case that does not fit well into a clear and evidence-based diagnostic pattern, or when I find something I have not seen before, I don’t charge the client for my scan and I call in a specialist who is better equipped to evaluate and handle the case.
Maximizing the potential of GPs does not mean disdaining specialists or not referring cases when appropriate. It means delineating the domains of the two rationally rather than by tradition or by organ system. EBM is a useful way to support primary care practitioners in developing their knowledge and skills, maintaining their job satisfaction, and providing high-quality care while also utilizing specialty and academic services when these are necessary and will benefit the patient.
Of course, even I recognize EBM can’t solve all of our problems. The lessons my students and new graduates are absorbing about their place in the profession are predominantly cultural lessons, expectations of the whole community as envisioned by a small subset of the profession. Academics don’t complain to their students about the failings and misjudgments of GPs because they are mean people. They do so because they see a skewed sample of cases that end up at the university. The most unusual, most difficult problems and those that have not been solved by primary care practitioners are most of the cases that make it to the teaching hospitals. All the cases we manage successfully, often within strict constraints of money and other resources, are invisible to those who teach students how to view the general practice role.
As a profession, we have to think deeply about how we understand the categories of general practitioner, specialist, and academic. If we want to avoid the excessive costs and harm to patient care that have come from hyperspecialization in human medicine, and if we want to provide satisfying and challenging careers for all new veterinarians, we need to avoid the trap of seeing academia and specialty practice as the brass ring and primary care as a consolation prize.
Stull JW, Shelby JA, Bonnett BN, et al. Barriers and next steps to providing a spectrum of effective health care to companion animals. J Am Vet Med Assoc. 2018;253(11):1386-1389. doi:10.2460/javma.253.11.1386
Nutrition is one of the most frequent subjects my clients want to discuss, and often one of the most controversial. Raw diets,1 vegetarian or vegan pet foods,2 ketogenic diets for pets,3 the significance of “artificial” versus “natural” pet food ingredients,4 and the fundamental question of whether veterinarians are trusted counselors when it comes to nutrition are just some of the controversies in pet nutrition I have covered in Veterinary Practice News.
These are all tough issues, both because of the passionate opinions they engender and because of the inevitably limited and imperfect scientific evidence available to adjudicate them. A key tenet of evidence-based medicine, however, is that we have to make judgments based on the evidence we have, not the evidence we wish we had. Another core principle is that our confidence in any judgment we make should only be as strong as the evidence allows.
Today’s topic is one where claims and passions far exceed the available evidence—fresh pet food. Various terms are used to describe such diets, including fresh, lightly-cooked, whole-food, etc., and there is no standardized terminology for these diets. I will mostly use “fresh food” as a shorthand for the myriad diets marketed in this way.
In addition to homemade fresh diets prepared by individual dog owners, a number of companies are now selling cooked commercial diets that are designed and packaged like fresh, homemade foods rather than extruded kibble or traditional canned pet food. These companies market such diets with implicit, or often explicit, claims that they are healthier than traditional commercial foods.
In an extreme example, the founders of Just Food for Dogs (JFFD) have written a polemical book titled “Big Kibble: The Hidden Dangers of the Pet Food Industry” to promote their alternative to traditional commercial diets. They have not been restrained or respectful in their response to criticism of their claims and marketing methods. The company explicitly claims their product is healthier that traditional kibble, and the leaders are not impressed by calls for evidence to prove this: “The mainstream veterinarian needs research and proof that real food is healthier, and that just boggles my mind,” Dr. Chavez adds. “We’re the last healthcare profession that is recommending an ultra-processed daily sustenance. It’s just crazy.”
So, is it crazy to wonder if fresh foods really are healthier than canned or kibble? Can we assume that dogs eating traditional commercial diets will have shorter lives and more health problems than dogs eating fresh diets? Regular readers of this column will already know my answer—nope! Equally “obvious” claims about the complicated relationship between environmental factors and health outcomes have been stunningly wrong many times in the history of human and veterinary medicine, and we should place very little confidence such beliefs without scientific evidence.
The ideal evidence for these claims, of course, would be long-term comparative feeding studies showing dogs eating fresh diets live longer and experience less disease than those eating kibble or canned foods. Such studies would be extremely complex and expensive to run, and I don’t see much chance companies on either side of the debate will step up to support them. This means that, as usual, we need to rely on less robust evidence (and proportion our confidence accordingly).
There is certainly epidemiologic evidence that consumption of whole foods, particularly fruits and vegetables, is associated with improved health outcomes in people compared with packaged and convenience foods. But it needs to be emphasized that commercial dog food is not the nutritional equivalent of potato chips just because both come in bags. Human snack and convenience foods are deliberately designed to be appealing, not nutritious. Pet foods are formulated with much more emphasis on nutritional value, and have been used and evaluated extensively for decades for their impact on health. They may well not be the optimal food we should be feeding, but they are hardly the egregious poison their detractors claim. And as the analogy breaks down, so does the relevance of the epidemiologic evidence in humans to pet feeding practices.
There is little direct research on the potential health impact of fresh diets compared with other cooked pet foods. There is research showing that homemade diets are often nutritionally unbalanced and incomplete, but little evidence pertaining to commercial cooked fresh diets.5–10
A small study was reported as a poster at the 2014 American Academy of Veterinary Nutrition Research Symposium, and this is often cited by fresh food advocates as positive evidence for their claims. Twenty-one dogs of various breeds were transitioned from kibble to a frozen cooked fresh-food diet and basic bloodwork and exams were conducted at the beginning of feeding the diet and again at 6 months and twelve months later. This was a pilot study, so there was no control group, no blinding, no pre-specified outcomes or hypotheses, no reported accounting for repeated measures or multiple comparisons in the statistical analysis, no discussion of any other aspects of the dogs’ health or environment, and overall no significant control for bias or random error. This limitation is especially relevant given that the lead author is Chief Medical Officer for JFFD and also an author of the book I mentioned earlier.
A few differences were found in some clinical laboratory measures before and after the transition to the JFFD diet. Increases were seen in red blood cell count and globulins, for example, though all values remained within reference intervals for all dogs. This sort of data might suggest hypotheses for future testing, but it doesn’t support any specific conclusions about the relative merits or health effects of different types of diet. It certainly does not support the claims in a JFFD press release that their foods “could benefit immune health” and that if the purported trends in the blood values continue for a lifetime “we may see a decrease in chronic diseases such as cancer, renal failure, kidney disease, inflammatory bowel disease, dental disease, etc.”
There is some laboratory research showing fresh diets have higher digestibility than extruded pet foods, and there may be effects on gut flora and other physiologic parameters.11–14 However, these are, once again, only useful bits of data that suggest testable hypotheses, not conclusive evidence for real-world health effects.
Personally, I am sympathetic to the hypothesis that pet diet which contain less processed whole ingredients may be superior to conventional canned or extruded dry diets in terms of health outcomes. The epidemiologic evidence in humans, and pre-clinical research in laboratory animal models is suggestive, though by no means conclusive. There are, of course, other issues besides health impacts that must be considered in comparing the merits of different types of pet food. The affordability and accessibility of different diets, storage and stability, safety, environmental sustainability, and many other factors are relevant as well to the recommendations of veterinarians and the feeding choices of dog owners.
The bottom line, as always, is that we should make decisions based on the best possible evidence, and we should limit our claims and confidence to what the evidence can support. Currently, the most optimistic assessment of diets identified by marketing materials as fresh, lightly-cooked, whole-food, human-grade, etc. is that it is plausible they may have health benefits if properly formulated by veterinary nutritionists and properly handled and fed by owners. Biologic plausibility and pre-clinical evidence are necessary starting points, but evidence from the real world on meaningful health outcomes will be needed before we can have any confidence in claims about the benefits of such diets.
1. McKenzie BA. Debating Raw Diets. Vet Pract News. January 2019:30-31.
2. McKenzie B. Are Vegan of Vegetarian Diets Good for Pets? Vet Pract News. July 2019:26-27.
3. McKenzie BA. Is Keto Kind to Pets? Vet Pract News. January 2020:30-31.
4. McKenzie B. Is banning “artificial” ingredients based on fear or science? Vet Pract News. March 2019:36-37.
5. Lauten S, Smith T, Kirk C. Computer analysis of nutrient sufficiency of published home-cooked diets for dogs and cats [abstract]. J Vet Intern Med. 2005;19(3):476-477.
6. Heinze CR, Gomez FC, Freeman LM. Assessment of commercial diets and recipes for home-prepared diets recommended for dogs with cancer. J Am Vet Med Assoc. 2012;241(11):1453-1460. doi:10.2460/javma.241.11.1453
7. Larsen JA, Parks EM, Heinze CR, Fascetti AJ. Evaluation of recipes for home-prepared diets for dogs and cats with chronic kidney disease. J Am Vet Med Assoc. 2012;240(5):532-538. doi:10.2460/javma.240.5.532
8. Taylor MB, Geiger DA, Saker KE, Larson MM. Diffuse osteopenia and myelopathy in a puppy fed a diet composed of an organic premix and raw ground beef. J Am Vet Med Assoc. 2009;234(8):1041-1048. doi:10.2460/javma.234.8.1041
9. ROUDEBUSH P, COWELL CS. Results of a Hypoallergenic Diet Survey of Veterinarians in North America with a Nutritional Evaluation of Homemade Diet Prescriptions. Vet Dermatol. 1992;3(1):23-28. doi:10.1111/j.1365-3164.1992.tb00139.x
10. Pedrinelli V, Gomes M de OS, Carciofi AC. Analysis of recipes of home-prepared diets for dogs and cats published in Portuguese. J Nutr Sci. 2017;6:e33. doi:10.1017/jns.2017.31
11. Oba PM, Utterback PL, Parsons CM, Swanson KS. True nutrient and amino acid digestibility of dog foods made with human-grade ingredients using the precision-fed cecectomized rooster assay1. Transl Anim Sci. 2020;4(1):442-451. doi:10.1093/tas/txz175
12. Do S, Phungviwatnikul T, de Godoy MRC, Swanson KS. Nutrient digestibility and fecal characteristics, microbiota, and metabolites in dogs fed human-grade foods. J Anim Sci. 2021;99(2). doi:10.1093/jas/skab028
13. Tanprasertsuk J, Perry LM, Tate DE, Honaker RW, Shmalberg J. Apparent total tract nutrient digestibility and metabolizable energy estimation in commercial fresh and extruded dry kibble dog foods. Transl Anim Sci. 2021;5(3). doi:10.1093/tas/txab071
14. Buff PR, Carter RA, Bauer JE, Kersey JH. Natural pet food: A review of natural diets and their impact on canine and feline physiology. J Anim Sci. 2014;92(9):3781-3791. doi:10.2527/jas.2014-7789
Regular readers may have noticed I’ve become a bit obsessed with canine aging biology lately. I’ve been reading everything I can get my hands on, from journal articles and textbooks to popular science books. I’ve also been writing about the subject constantly, including journal articles (JAVMA, in press), columns and website pieces for Veterinary Practice News, and of course blog posts and book reviews here. Most of the scientific literature on aging biology involves animal models (predominantly worms, fruit flies, and mice) or humans, so I am always hunting for more evidence relevant to canine aging.
Imagine my excitement, then, to see the first book specifically purporting to focus on aging and longevity in the dog!
Imagine, also, my disappointment at seeing it was written by two of the least qualified, least reliable promoters of pseudoscience in the pet health space. We need this book, but sadly this is not the book we need.
Karen Becker is a veterinarian who runs the animal-centered portion of uber-quack Joseph Mercola’s misinformation empire. I’ve written about her claims and views many times (1, 2, 3, 4, 5, 6, 7), and the following summary is as applicable to this book as to the Truth About Pet Cancer propaganda project for which I wrote it.
She practices homeopathy, acupuncture, and herbal medicine, and she routinely condemns conventional medicine and nutrition practices as “toxic” and ineffective. To hear her tell it, our pets are living in the most horrible, toxic world possible, suffering and dying constantly due to unnatural and poisonous food, water, air, and medicines, and science-based veterinarians are clueless or corrupt and so only make things worse.
Dr. Becker is one of the more consistently anti-science voices in the veterinary profession, despite paying lip service to science and misusing or cherry-picking evidence when it suits her ideology. The fact that she is one of the drivers of this [book] undermines the credibility of [it] and illustrates the barely concealed anti-science agenda behind it.
Rodney Habib is a social media influencer who has manufactured a lucrative role for himself as a pet health expert entirely out of his communications skills and opinions, with no actual training or expertise in science or veterinary medicine. As I wrote in reference to the same pet cancer propaganda series,
While it is possible to admire Mr. Habib’s passion and success as a manipulator of the media, unfortunately most of what he is selling is pseudoscientific nonsense. He skillfully uses social media to instill fear in pet owners; fear of pet food, vaccines, and virtually anything mainstream veterinary medicine recommends. And despite absolutely no training or expertise in science, he confidently tells the public that vets and scientists have it all wrong, and they should listen to his advice instead.
Despite the negligible odds that a book on aging by these two authors would be a sound, science-based treatment of the subject, it is likely to be widely read and influential, and one tries never to give up hope. So I committed to reading it thoroughly, and with an open mind. Even when I quickly discovered that it is not really a book about aging but simply a new packaging of the same ideas Becker and Habib have been selling for years, I made a point of carefully reading Forever Dog in its entirety.
As with the other popular science books on aging I have read, there are a few worthwhile things to be found here. Unlike the others, however, there is far, far more misinformation and ideology than legitimate scientific information in the book. Dog owners are likely to learn very little about canine aging biology, and they are likely to come away with a distorted view of what we know and don’t know about how dogs age and how we can improve healthspan and lifespan.
I will share my thoughts in excruciating detail on many specific claims and ideas set forth in Forever Dog below. However, for the majority of you not battling pseudoscience and misinformation on a daily basis, most of that will be of little use or interest, so I will start with a more general review of the core ideas and claims in the book as well as the most critical failures.
As I mentioned, this isn’t really a book about canine aging. There are some sections that review aging biology generally in a cursory manner, predominantly with the goal of setting up specific beliefs the authors want to promote. But the core of the book is the same old tropes that Habib and Becker promote in the Truth About Pet Cancer and on their internet sites. This book is all about using the current excitement about aging and about the potential to use our scientific understanding of it to improve lifespan and health as a shiny new display case for the same old ideology of alternative medicine that they and others have been promoting for decades. There are few new ideas and little real science here, just a new frame for old ideas.
Here are the core ideas Forever Dog is designed to sell:
Modernity is bad
This is not only an implicit message repeated on most every page, there is even a section entitled “The Hazards of Modernity that Lessen Longevity” and another called “The Modern Unwell Dog.” The same arguments they make in Truth about Pet Cancer and elsewhere against neutering, vaccination, commercial pet food, conventional medicines, electronic devices, “chemicals,” etc. reappear here, dressed up to look like they are connected to aging and longevity in dogs.
The authors are peddling a regressive view of history. They have one leitmotif which they repeat in a dozen different forms and settings: modernity is the root of all evil and we must retreat to some mythical simpler, cleaner past before technology ruined everyone’s life and health.
The Naturalistic Fallacy
The obvious corollary to “modernity is bad” is, of course, “nature is good.” Nature, as used by Becker and Habib, is a mythical construct, usually centered in the past or in rural environments, in which health was optimal because humans hadn’t discovered or invented anything yet. The idea of nature as benign, even Edenic, is a silly fantasy only possible for people raised and embedded in a safe, technological society greatly distanced from the experience most humans had of nature for most of our species’ history.
Health is a Personal Belief System
The authors go out of their way to emphasize that what matters most in caring for your dog’s health is what you believe. They have particular beliefs they want to sell you, of course, but they take pains to emphasize that you should “do your research” and “educate yourself” and that your observations and intuitions and feelings are ultimately the most important guide to what is good or bad for your dogs. Pet owners are responsible for their pets’ health (especially since vets and other “experts” can’t be trusted), and they shouldn’t doubt their own instincts or ability to teach themselves everything they need to know to confidently disregard science and scientific expertise. This idea is closely connected to the next,
Science is Optional
Despite the frequent references to science, from the title to the citations the authors have relegated to their web site, in the universe of Forever Dog science exists only to validate what we already know through other means. Scientific studies are cited when they support the authors’ beliefs, and the exact same studies are ignored when they do not. These authors cherry pick, distort and ignore scientific evidence freely, without any apparent concern for how scientific research works and what the evidence can reasonable be understood to mean. Science is mere window-dressing, giving a patina of legitimacy and seriousness to ideas that are fundamentally ideological and only connected to reality through personal observation and anecdote.
Be Afraid, Be Very Afraid
The authors paint a terrifying picture of the modern world as a toxic wasteland full of dangers and unscrupulous or misinformed false experts offering you bad advice for money. They need you to be afraid so that you will eagerly embrace the anodyne they offer for the malady they have created. And they do offer a way out of the nightmare, by giving you a sense of understanding, competence, agency, and validation in making your own decisions that they promise will miraculously transform the health of your pet, just like the pets in the numerous miracle stories that open many of the chapters. Marketers of all stripes have discovered the persuasive power of anxiety to undermine confidence in their current sources of information and drive them to seek eagerly after another.
It is not true to say that every point made in the book is wrong. In some ways, it would be a much less dangerous vehicle for misinformation if that were the case. The authors employ legitimate scientific information, plausible and sensible advice, and accurate comments on the many flaws of the human and animal healthcare systems, the pharmaceutical industry, and the pet food industry as part of their argument. They weave reality together with opinion and fantasy almost seamlessly, until it is difficult for the reader to tell them apart.
For example, they may provide a reasonable and accurate summary of the many health dangers of obesity in dogs, and then they tell you how to save your dog from this terrible condition by following their nutritional advice, which is mostly exaggeration and invention not supported by real science or real experts in nutrition. Or they might talk with justifiable enthusiasm about the potential of epigenetics to transform preventative medicine, and then just blithely assume that some specific food or supplement can radically extend healthpsan and lifespan by altering gene expression, even though this has never been tested in dogs, much less shown to work.
One of their favorite tactics is to cite legitimate scientists out of context, ignoring the fact that their words may be pure speculation, radically out of step with most experts in their field, or simply not intended to mean what the authors claim they mean. This was a technique used extensively in the Truth About Pet Cancer. Some of the experts interviewed in that project, such as veterinary oncologist Dr. Greg Ogilvie, were outraged at the way their work and comments were misused to promote ideas they do not support.
A few of their arguments in Forever Dog are plausible and may even turn out to be true. As I’ve said many times, I suspect fresh food diets may have health advantages over conventional pet foods, and I look forward to seeing robust scientific evidence demonstrating this. Once it arrives, I will be happy to change my position from neutral to strongly in favor of such diets. If it never arrives because my guesses about these diets are wrong, then I will accept that as part of the ongoing process of using science to more accurately understand the world and improve the health of my patients. But my recommendations will be driven by the data, not by what I want to be true.
However, even if Becker and Habib provide some information that is accurate and some that is unproven but at least plausible, they provide much more that is purely an expression of their personal beliefs and supported by no more than anecdote and motivated reasoning. In other cases, their recommendations are not only unproven but almost certainly wrong.
They do a masterful job of generating fear and then assuaging it with simple, clear advice. Dog owners naturally want clear directives on how to extend life and health for their dogs, and these authors give many. The problem is that directives based on little or no evidence and largely fabricated out of ideological bias, theory, preclinical data from cell cultures and rodents, or wishful thinking may satisfy our need for agency, but they aren’t likely to have any real benefits for our dogs. A belief-based approach that disdains science except where it can be twisted to support preconceived ideas is not a reliable way to improve healthspan or lifespan.
In Forever Dog, Dr. Becker and Mr. Habib have created a case study in the slick and effective marketing of ideology and misinformation. I have little doubt they believe much of what they say, and that they feel they are doing vital work to benefit the health of dogs and humans. That doesn’t make them any less wrong, and it doesn’t make their misinformation any less dangerous to those who are led into mistrust of legitimate science, scientists, and veterinary health professionals.
I believe enthusiastically in the potential for science to help us extend lifespan and healthspan in dogs and in humans. I also believe that we have a lot of hard work to do to realize this potential. It will come about through rigorous scientific research, not the liberal application of anecdotes, cherry picked evidence, and personal ideology to the problem of aging. We will likely be proven wrong more often than right, as is common in science, because nature is much more intricate and complex than we imagine it to be. Nevertheless, I am, as one of my mentors in the aging biology field often says of himself, a skeptical optimist.
When the true story of how we came to make our dogs live much longer and healthier lives than they do now is written, it will be far more interesting and substantial than this confection of ideology and wishful thinking. The real story of how we solved canine aging will be the fruit of rigorous, painstaking work by thousands of people committed to understanding reality as it is. Scientific progress often lacks the glamor and instant gratification of propaganda pieces like this book, but it does what pseudoscience never can—it reduces suffering and improves the quality of life for us and our dogs.
What follows is a collection of specific claims and arguments made in Forever Dog that are unproven, implausible, or simply wrong. Many of these are ideas I have written about before simply because the book is largely a repackaging of stale alternative medicine beliefs reframed around aging. Where possible, I have provided links or citations to the sources cited by the authors and those I believe provide additional information and clarification. Many of the latter are articles or blog posts I have written because these already include summaries of the relevant evidence. I am not merely citing my own opinions to refute those of Dr. Becker and Mr. Habib; I am linking to work already done elsewhere to find and explain the actual scientific research bearing on their claims.
Dogs are less healthy than they used to be and are probably not living as long.
Examples The first section of the book is titled “The Modern Unwell Dog” and the first chapter is “Sick as a Dog- Why we and our companions are losing our longevity.”
“By some measures we’ve witnessed a decline in canine longevity…Although many dogs are indeed living longer, like people, many dogs are dying prematurely of more chronic disease than ever before.”
The authors also use much more histrionic language, referring to “the near extinction of the healthy dog in modern times.”
They claim that even if it is not possible to prove canine lifespan has declined,
“certainly their health span has diminished. A dog’s life is not as happy as it used to be.”
“Modern lifestyle often separates humans (and animals) from making direct contact with earth. The research suggests that this disconnect may be a contributor to physiological dysfunction and unwellness.”
“Fifty years ago, vets saw patients primarily for acute injuries and infectious diseases. But these days most patients we see are suffering with GI problems, allergies and skin issues, musculoskeletal issues, and organ dysfunction. It’s an epidemic.”
“When cells are relentlessly exposed to high levels of insulin as a result of the persistent presence of glucose—typically caused by consuming too much refined sugars and simple carbs from processed foods—our cells adapt by reducing the number of insulin receptors. This causes our cells to become desensitized or “resistant” to insulin, ultimately causing insulin resistance and eventually type 2 diabetes… ?Most dogs with diabetes also are born with a perfectly functioning pancreas (or diabetes would be diagnosed immediately, as a puppy). With time and insult, the pancreas stops producing adequate insulin, and once the insulin-producing cells are burned out, they’re done.”
[This misrepresents the pathogenesis of diabetes in dogs, which is largely due to genetic predisposition and diseases that lead to insufficient insulin production. This is very different from the type of diabetes most common in humans, which is due to peripheral insulin resistance associated with metabolic abnormalities. Diet, and obesity due to excess calorie intake, is clearly a risk factor for Type II diabetes in humans. It is not at all clear, however, that diet is a meaningful factor in the development of canine Type I diabetes. Low-carbohydrate diets are not useful in managing diabetes in dogs, as they are in cats, and there is no reason to believe dietary carbohydrates are a risk factor for dogs developing diabetes since they differ in meaningful metabolic ways from humans. (1, 2, 3)
Response Dr. Becker has previously claimed that dogs are not living as long as they used to, and throughut the book the authors try to frighten the reader with claims that many aspects of modern life have led to a decline if lifespan and health in dogs. This is part of the general argument that modern life is bad for canine health and that some mystical pretechnological golden age existed in which dogs were healthier and happier. They are actually quite clear about viewing the invention of agriculture as the start of most of our health woes, and they idealize a supposed hunter-gatherer lifestyle as the optimal for health and well-being (ignoring the much higher rate of infant and childhood mortality of these groups compared to those of us living in the “toxic” modern world).
As for the claim that dogs are generally less healthy than they used to be, there is no evidence to support that belief, which is merely another expression of the hatred for modernity and the nostalgic longing for a mythical purer past.
The authors acknowledge that we have dramatically reduced causes of disease and death in children, such as infectious disease and trauma (though they assiduously avoid ever mentioning vaccines when talking about this), which is a major reason human life expectancy has increased dramatically. They also recognize that we have had similar success combating these ills in dogs. However, they seem unable to understand that the reduction in acute illness and the resultant aging of the population inevitably means that the proportion of diseases that are age-related and chronic must increase.
People, and probably dogs, used to experience less diabetes, heart disease, and cancer not because they lived in a healthier environment with better nutrition but because they rarely lived long enough! Early death from infection, malnutrition, and trauma precluded the development of such diseases, which represent our success at combating those health problems more than any fundamental degradation of the quality of our environment or nutrition. The predominant evolutionary explanations for why aging occurs at all center on the fact that we cannot have evolved resistance to chronic, age-related diseases when our ancestors rarely lived long enough to experience them. If they did it was long after they had reproduced, so it would not affect the genetic susceptibility to age-related disease in their descendants (us).
Like humans, dogs very likely live longer and healthier lives than ever before, at least in places where they are treated as Habib and Becker agree they should be- as beloved family members given the best possible care. There are many serious health problems that dogs face, and we absolutely must continue to examine scientifically the causes and means of preventing and treating these. Intervening in the core pathways of aging is likely to be a very effective strategy for improving lifespan and healthspan, but we must base our interventions on a sound understanding of how aging works, not on the myth that we live in a fallen world and that the answer is to reject modernity and return to the lifestyle of a mythical natural paradise in the past.
Commercial Diets are Terrible for Dog Health (except raw and fresh diets)
This is probably the most vehement and consistent message of Forever Dog. The way most of us feed our dogs, using commercial kibble or canned food, is the equivalent of eating nothing but fast food and packaged snacks, and we are killing our canine companions with these foods.
“Understanding how the pet food industry became a $60 billion fast-food engine in less than sixty years will shed light on a large part of the problem.”
Defines “ultra-processed foods as “formulations mostly of cheap industrial sources of dietary energy and nutrients plus additives, using a series of processes (hence ‘ultra-processed’). All together, they are high in unhealthy types of fat, refined starches, free sugars and salt, and poor sources of protein, dietary fiber, and micronutrients.”
When we eat “ultra-processed, pro-inflammatory food, not only do the insulin flow and blood sugar levels run amok, but the trash starts to pile up in your cells.”
“While there aren’t any lifetime studies comparing dogs that eat one ultra-processed diet versus a variety of less-processed foods from birth to death, common sense tells us something is wrong with the nutrition picture Big Pet Food has painted for us.”
Commercial pet foods are ?“ultra-processed fare that threatens the lives and well-being of our companion animals.”
“Let food be your medicine” attributed to Hippocrates
The bottom line is that contemporary commercial diets are likely not the “perfect” diet to maximize health and longevity for dogs. They are also not the toxic waste in a bag bringing death closer with every bite that Habib and Becker claim. While there are legitimate questions to be asked about the relative risks and benefits of conventional diets and other feeding strategies, this book simply assumes the worst without any real, substantive evidence. The authors ignore decades of nutrition research and the lived experience of millions of healthy, happy dogs in favor of careless extrapolation and exaggeration of theoretical concerns and research in humans or lab animals. As with the book in general, the information on nutrition is a mixture of a few facts, lots of untested beliefs and assumptions, and a fair number of outright falsehoods.
The Satanization of Carbohydrates
An abiding theme in alternative nutrition for many years now is that carbohydrates are inherently unhealthy. This book at least pays some lip service to distinguishing simple and complex carbohydrates, but they misrepresent the composition of commercial pet foods and the evidence concerning the potential health effects of various carbohydrates in dog diets.
The authors make much of the “glycemic index,” a method for assessing the impact of various carbohydrates on blood sugar levels in humans. They also misleadingly refer to all simple carbohydrates as “sugar” which is simply false. The glycemic index has not been thoroughly validated in dogs, and there is certainly no research to support the idea that we can use it to determine which foods raise the risk of disease. The response of dogs to simple and complex carbohydrates is not always the same as in humans, so the use of this measure to decide if a food is “healthy” is not justified.
Unlike humans, dogs and cats don’t require carbohydrates. However, they can utilize this class of macronutrient perfectly well.17,24–28 Some non-digestible carbohydrates can have also beneficial effects on the microbiome, which can influences weight, stool consistency, and other aspects of health.29 There is no reliable scientific evidence supporting claims that dietary carbohydrates cause cancer in pets or that lower carbs will prevent or help treat cancer. And while carbohydrates are often seen as particularly dangerous to cats, research has demonstrated that this species can effectively utilize carbohydrates in food and that these are not a significant risk factor for diabetes or other diseases often blamed on too much carbohydrate in commercial cat food.17,25,30 (see here for references)
The authors also state that “?dogs fed dry and/or canned food were more likely to be overweight or obese” and, unusually, they cite a specific study to support this claim. Unfortunately, this is another example of their selective use of science only to support what they already believe. The study is what is called a “preprint,” meaning it hasn’t been peer-reviewed and published in a journal yet. Such studies sometimes pass review and get published, and sometimes they are withdrawn once experts in the field have a chance to look at them closely (this has happened frequently with influential papers looking at alternative ideas about COVID-19). Furthermore, the author of the paper is a neuroscientist, not a nutritionist or veterinarian, and she works for a company selling a fresh commercial dog food. The potential for bias here is at least as great as in all the research supporting conventional diets, which Habib and Becker dismissed as industry propaganda.
The study itself was another owner survey, mostly of customers buying the diet sold by the lead author’s company. This is more a reflection of what this population of owners believes about their dogs than anything else. The study also found “conventional-only medicine” to be a risk factor for obesity, which shouldn’t be surprising given that one of the other authors was an “integrative medicine” veterinarian. Interesting as these findings are, they are hardly a reliable foundation for a novel and strong conclusion about the role of diet in canine health.
“Despite the large number of dog owners who are averse to feeding carbohydrates to their pets, there is little evidence to support the contention that any negative health effects result from feeding diets that provide dietary carbohydrates in amounts (30% to 60% DM) commonly found in commercial extruded pet foods. There appears to be no association between dietary carbohydrate and the development of obesity, diabetes mellitus, cancer, or adverse food reactions in dogs. In fact, dogs appear to have evolved so that they can metabolize substantial quantities of carbohydrate. Increasing the amount of complex carbohydrates in diets results in the reduction of dietary protein or fat (or both), which may provide benefits for dogs with certain conditions, such as obesity, diabetes mellitus with concurrent pancreatitis, or adverse food reactions.”
Cooking = ”Heat Adulteration”
The authors are clearly in favor of raw foods, though they realize this may not be an attractive option for many dog owners and so also make allowances for “minimal” heat processing. However, they repeatedly refer to cooking as “heat adulteration,” and they clearly want to make the case that it is a dangerous cause of health problems in dogs.
“Better: Homemade, commercial raw or gently cooked, freeze-dried, and dehydrated real dog foods are all substantially less adulterated pet food choices, and fall into the “fresher” category, when compared to ultra-processed kibble and canned food.”
“Assessing the number of times the ingredients in pet foods are heat-adulterated is an important consideration in selecting which foods to feed your dog.”
“We use the word “raw” sparingly because it’s only one option in the minimally processed pet food category, and it evokes in many people’s minds stereotypical images of contamination, or foul and rotting flesh, instead of images of the neighborhood butcher shop. The unfortunate connotation behind “raw” has stalled the preventive health revolution and distracted many well-meaning pet parents from giving their furry beloveds what they instinctually want and genetically need.”
“Raw food is less metabolically stressful than kibble and that raw-fed dogs have lower levels of inflammatory and disease markers, including homocysteine levels, compared to kibble-fed dogs.”
“Raw-fed dogs can have much lower fasting glucose levels than starch-fed dogs.”
[As if “raw” and “starch” were the only options?]
“Raw diets foster a much richer, more diversified gut community of organisms.”
“Repeated heating also obliterates the “entourage effect” of whole, raw foods.”
“The average bag of dry dog food contains ingredients that have been high-heat processed at least four times; it is literally dead food.”
[As if we should be feeding “living” food? This is classic vitalism]
I have written about raw diets many times (e.g. 1, 2) and the bottom line has yet to change:
No evidence of benefits
Plenty of evidence of risks
Sure, plenty of dogs get away with eating raw meat, but some suffer serious harm. Until there is robust scientific evidence for health benefits, there is simply no reason to take such risks. High-pressure pasteurization can reduce the risk of infectious disease in raw foods, but even with the lessened risk it is important to recognize that none of the health benefits these authors claim for raw diets have actually been shown to exist. Raw foods are not the distillation of evil any more than commercial kibble is. They are, however, an expression of ideology more than a science-based feeding choice.
I have also written about so-called “fresh” diets, those “lightly cooked” foods such as Just Food for Dogs. These seem more likely to have some health benefits and fewer risks than raw meat based diets, but the claims of proponents of such diets go well beyond the available evidence. It should be possible to investigate the potential benefits of such diets without the kind of egregious fear-mongering and misinformation used in Forever Dog.
Much of the minimal evidence that is cited in support of raw and fresh diets comes from research by DogRisk, a collection of Finnish researchers this group contributed to Becker and Habib’s notorious Truth About Pet Cancer series, and they have published some studies investigating various types of dog nutrition, including raw diets. These studies are mostly based on online owner surveys, again reflecting the beliefs and perceptions of raw feeders about their dogs’ health more than anything else. This is interesting information, but it does not even remotely constitute validation of the claims made in this book for the health benefits of raw or lightly cooked foods.
Fasting and Time-limited Feeding
“Cramming all your dog’s calories into a set period of time during the day does amazing things for her physiology. Aside from maintaining “cellular youth” and slowing aging, research has shown that the practice promotes greater energy, increases fat burning, and decreases risk of developing diseases such as diabetes and heart disease, all because fasting activates autophagy, or cellular housecleaning.”
This is certainly one of the hottest topics in the aging field. There is strong evidence, including in dogs, that some kinds of caloric or dietary restriction can extend healthspan and lifespan. However, the differences between various specific feeding strategies and how they affect health in yeast and worms and flies and mice and humans, in males and females, in obese and lean individuals, and in subject with different genetic backgrounds are enormous. We are just beginning to understand how the results of laboratory and exploratory studies of caloric restriction, time-limited feeding can be used to inform strategies that will improve health and lifespan in a diverse population in the real world.
These authors, characteristically, latch on to the enthusiasm and the potential and complexly ignore the complexity and uncertainty. Studies of caloric restriction and various types of time-restricted feeding have shown mixed results, with some strategies having no effect or even potentially causing harm., such as loss of muscle mass or metabolic dysfunction (e.g. 3,4,5,6,7,8,9)
Very little research has been done of caloric restriction and specific time-limited feeding practices in dogs. It is very likely that some version of these practices will ultimately be beneficial for health and longevity in dogs. It is also likely that some versions will be harmful to some dogs. Since we don’t know which is which yet, the blithe recommendations in this book to feed your dog only during an eight-hour window of time is not justified, it is just a wild guess made by the authors.
The Environment is Horribly Toxic
The authors of Forever Dog make extensive use of the concept of “toxins” to paint a frightening picture of the health danger sin modern life. While there is no doubt that some environmental exposures can increase health risks, the slapdash way the terms “toxin” and “chemical” are used here has nothing to do with legitimate scientific toxicology or epidemiology. It is, once again, merely an expression of the belief that anything modern and technological is bad (except when it isn’t) and anything that meets their vapid criteria for being “natural” is good.
I can’t possibly address every single purported toxin they mention without writing another book, but I will try to give enough examples to illustrate the pattern of exaggeration and misinformation.
Examples We should make sure our pets “eat and drink from chemical-free bowls.”
[as if everything, from the bowls to the food and water, isn’t made of “chemicals”!]
“Exposure to lawn pesticides (specifically those applied by professional lawn-care companies) raise the risk of canine malignant lymphoma by as much as 70 percent.”
“The Dirty Dozen: ethoxyquin, menadione, dyes and colors (including caramel), poultry (animal) digest, animal fat, propylene glycol, soybean oil, by-products, corn gluten meal, BHA/BHT, meat meals, and sodium selenite.”
“?Look for ingredients that do not sound like synthetic agro-chemicals. Some of the organic herbicides use citric acid, clove oil, cinnamon oil, lemongrass oil, d-limonene (from limes), and acetic acid (vinegar).”
[A variation on the idea that somehow things with simpler names are more “natural” and healthier than things with complicated names]
“Modern lifestyle often separates humans (and animals) from making direct contact with earth. The research suggests that this disconnect may be a contributor to physiological dysfunction and unwellness. Reconnection with the physical earth has been found to promote intriguing physiological changes and subjective reports of well-being.”
“There are important relationships between the Earth’s rhythms and resonance and a wide range of human and animal wellness indicators…We hypothesize that it’s important for your dog to have regular opportunities to directly touch the earth on a regular basis. Preferably several times a day… All animals, given the option, will use the Earth’s magnetic fields to their benefit.”
“Living in a city (and oftentimes the ’burbs), generally means a more fast-paced, stressful life for people (ahem: dog owners) who are working long hours and are more likely to spend the majority of their day indoors under artificial light
“Household air can be a toxic cocktail”
“Leaving shoes outside the house can be one of the easiest, free things you can do to help your pets (and yourself) avoid exposures to harmful substances, ranging from those lawn chemicals in your hood, carcinogens in asphalt and petroleum by-products, and fecal matter on pavement to pathogenic (bad) bacteria, viruses, and toxic dust and chemicals…?you. In fact, your shoes may be even more toxic than your toilet!”
Response Most of the claims of toxic effects for specific chemicals are either extrapolated from lab animal research or too vague to make much sense. Some are plausible but unproven. Others are likely accurate to a point but much more complicated than the authors understand (or admit).
For example, take the claim that “Exposure to lawn pesticides (specifically those applied by professional lawn-care companies) raise the risk of canine malignant lymphoma by as much as 70 percent.” This is based on a case-control study in which owners were asked to fill out a questionnaire about possible exposures their pets had experienced. This is a notoriously unreliable way of assessing environmental risk factors, and it isn’t sufficient alone to establish a causal relationship under the best of circumstances.
In this case, the evidence is especially weak. No overall difference in lawn chemical exposure was found between dogs with and without lymphoma. That means the basic hypothesis, that use of lawn chemicals was more common in dogs with cancer, wasn’t shown to be true. There was also no difference found in the exposure to most lawn chemicals applied by owners, the number of different products dogs were exposed to, or the use of flea and tick products. The only association found was between lawn chemicals applied by a professional service and lymphoma.
The most accurate representation of this study would be that most chemicals investigated had no association with this type of cancer. One subset, those applied by a professional service, might have been a risk factor, and this deserves further investigate. The authors prefer to cherry pick the only positive findings and use it to support a general implication that all environmental “chemicals” are unhealthy.
It was especially interesting that the study found no association between lymphoma and the use of flea and tick products. The authors frequently identify such products as health hazards and even claim that uncontrolled spontaneous reports by owners are evidence for this. Yet when discussing flea and tick products, they somehow fail to mention that an actual scientific study, one they themselves cite in the book, did not find a connection. This is a typical example of how these authors misuse science only to support their case and ignore evidence which does not.
The authors make quite a fuss about the indoor environment being toxic and the benefits of letting your dog outside. Paradoxically, they also warn you to wipe your dogs’ feet and take off your shoes in the house to remove outdoors toxins. In general, they seem to believe that rural environments are healthier than the city or the suburbs and that the outdoors is an antidote to the poisonous indoors. This is clearly another manifestation of the irrational phobia about the modern, technological world and a fantasy of a purer pre-technological time or place.
The evidence suggests this view is not accurate. For humans, at least, rural life is associated with poorer health outcomes, more behavioral problems, and less leisure time. The authors do cite a survey that suggests urban dogs are more fearful than rural dogs, but this is likely due to differences in socialization and other characteristics of how they are raised and treated, not to a fundamentally “healthier” rural environment. Another study cited suggests urban dogs may be more likely to have allergies than those in rural environments. This is plausible but given that it was yet another survey conducted by the DogRisk research group, which shares many of the biases of these authors, there is reason to be skeptical. There is also evidence, which the authors ignore, that rural dogs may be less likely to be vaccinated for rabies and more likely to carry dangerous parasites. As always, the reality is likely complex and context-dependent, and the kind of simple narrative presented in this book is unrealistic.
This is a preservative implied to have negative health effects despite a lack of evidence for the truth of such claims. Much is made of the fact that it is permitted in the U.S. but not in Europe, suggesting real risks have been identified but the FDA has somehow failed to acknowledge them. There is no reason to think, however, that European regulatory decisions are any more evidence-based than those made in the U.S., or more effective in protecting public safety. It is easy to find examples of the opposite being true, such as the case of thalidomide, a drug approved for use in pregnant women in Europe, but not in the U.S., in the 1950s and 1960s which turned out to cause significant birth defects. In any case, the evidence does not support claims that ethoxyquin is harmful at levels used in pet foods: 1, 2, 3, 4, 5, 6, 7
A synthetic form of Vitamin K I have written about before. Under normal circumstances, dogs and cats need extremely small amounts of dietary Vitamin K. At the low levels of supplementation in commercial foods, menadione is a safe source of this Vitamin K. Toxic effects can be seen when enormous quantities are given to an animal or when menadione is used injectably, but there are no documented cases of any harmful effects from dietary supplementation of menadione in commercial pet foods. The three veterinary nutritionists and one veterinary toxicologist I consulted on this issue all agreed that there is no evidence of any significant risk from menadione in commercial pet foods. The concerns about this supplement seem to stem almost entirely from the appeal to nature fallacy and from the mistaken belief that substances are inherently either safe or toxic regardless of dose or route of exposure.
BHA and BHT have been used as preservatives in human and animal foods…for more than 30 years. While many countries have banned them from use in human foods, they are still allowed in pet foods…[and] have been indicated as carcinogenic in animal experiments and are suspected of contributing to cancer and tumor growth.
The purpose of these compounds is to function as anti-oxidants and prevent spoilage, which is itself a potential health risk. Extensive research has been done to investigate any dangers from these compounds, and the research generally does not support a significant risk at levels of exposure likely to be seen with use as a food preservative. In fact, there is even tenuous evidence that these compounds may be protective against cancer under some circumstances. It is never possible to exclude all possibility of risk, of course, but avoiding potentially beneficial products without any evidence of risk is not a rational way to make decisions about food safety.
Here is some of the evidence concerning these compounds: 1, 2, 3, 4, 5
Filtered water is claimed to be safer than tap water no matter how good it tastes or what data the water company has. While there is some evidence that filtration can reduce risk of bacterial GI Dz, though the results are inconsistent, there is no evidence regarding long-term health. Additionally, many home or “point-of-use” filtration systems have been shown not to work. (1)
Epigenetics is a relatively new scientific field which is revealing that expression of the genes we inherit is far more complicated, and potentially more responsive to internal and external influences, than previously understood. As always, proponents of alternative theories of health have seized on this new area of research, just as they misuse the concepts of quantum mechanics, to cast doubt on science-based practices and to support their own beliefs.
We are just at the beginning of learning what epigentic markers can tell us about health and how we can influence gene expression to potentially increase healthspan and lifespan. In a book I reviewed some time ago, Canine Nutrigenomics: The New Science of Feeding Your Dog for Optimum Health by Dr. Jean Dodds, I responded in detail to some wild claims about the impact of food on gene expression. Mr. Habib and Dr. Becker make many of the same unfounded leaps of imagination about epigenetics and how food and other external forces can influence health through epigenetic mechanisms. They take an exciting new idea and skip over all the hard work of investigation and understanding, simply assuming that what they hope and believe is true.
“You need to be utterly convinced that all aspects of your dog’s lifestyle and immediate environment are whispering to his DNA; it’s our job to ensure the space around him ?speaks only words of health, vitality, and resiliency to his epigenome.”
“You’re providing [supplements] to whisper longevity instructions to your dog’s epigenome.”
“We can use our genome to help direct what medicine and chemotherapy protocols are appropriate, and now which vitamins, minerals, and supplements will resonate best—or which should be avoided—with life-changing results.”
?“Already, wellness companies are creating customized nutraceutical protocols tailored to your dog’s DNA test results, breed predisposition(s), and lifestyle and life stage.”
“?Nutrigenomics, or the study of the interaction between nutrition and genes, particularly regarding disease prevention and treatment, is key to the health of all dogs. Nutrigenomics offers our dogs the possibility of reversible destiny.”
There is very little evidence that any specific food, feeding strategy, supplement, or other intervention can improve health or extend life by influencing gene expression in dogs or humans living in the real world. Nearly all the research is from laboratory or pilot studies, and it almost all illustrates interesting differences between limited sets of epigenetic markers associated with whatever variable is being studied—food, exercise, age, and many, many others. All of this is part of the necessary work in building an understanding of what these markers mean and how we can influence them.
What the research does not currently support is the idea that we can extend life and health in our dogs right now by changing their diet or other aspects of how we care for them. It isn’t that these things couldn’t be helpful, it’s that no one has done the studies to find out! Until that work is done, all of us will just be guessing, though hopefully most of us won’t be presenting our guesses as facts, the way these authors do.
This is just a hodgepodge of statements made in the book that are misleading or unreliable.
“While there aren’t any lifetime studies comparing dogs that eat one ultra-processed diet versus a variety of less-processed foods from birth to death, common sense tells us something is wrong with the nutrition picture Big Pet Food has painted for us.”
This is a nice pre-emptive way of avoiding having to prove their claims and allowing “common sense” to stand in for real evidence. Nearly every chapter begins with or includes some sort of miracle story in which a dog was healed or given extraordinary longevity by some practice the authors support. This use of anecdotes is as misleading as it is effective, because none of these stories prove anything except that we are a species that understands narrative and simple cognitive heuristics better than statistics and data. I have written many times about why reasoning from anecdote and intuition and “common sense” is unreliable, and this is the core flaw behind much of what is promoted in this book.
“Dogs, for instance, are much more sensitive to electromagnetic fields (EMF), which doesn’t bode well for our highly networked world where Wi-Fi grows more powerful and prevalent. We aren’t tinfoil hat–wearing conspiracists, but we know dogs, including a few of our own, hate being around 5G routers, which tells us we should honor their preferences and exceptional senses.”
“There are important relationships between the Earth’s rhythms and resonance and a wide range of human and animal wellness indicators…We hypothesize that it’s important for your dog to have regular opportunities to directly touch the earth on a regular basis. Preferably several times a day… All animals, given the option, will use the Earth’s magnetic fields to their benefit.”
These quotes are indirect references to both the nonsense about electromagnetic fields causing deleterious health effects and the concept of “earthing,” avoiding or relieving health problems through regular physical contact with the ground. The authors try to both promote these ideas while distancing themselves from the egregiously pseudoscientific BS they represent, but I don’t think they succeed. The statement that “sound is a form of electromagnetic radiation,” made in a section on the dangers of noise pollution, doesn’t help their case since this is clearly wrong and shows a lack of understanding of basic physics.
“Nourishment is not an exact science, and you can always change your mind, change percentages, or change your brand, depending on your food philosophy and what works best for you and your dog.”
“We trust you already feel empowered and validated by the science, allowing your common sense to reinforce what you already intuitively sensed…Your own personal beliefs ultimately determine the importance of each of these topics; a lower score in one area may be perfectly acceptable to you, and that’s all that matters…There aren’t right or wrong answers; this is about the power of knowledge propelling you to make informed, smart decisions for you, your lifestyle and beliefs, and your dog’s needs.”
“There’s no right or wrong schedule, so do what works for you and your dog’s physiology and your schedule.”
Owner should find their “personal food philosophy” and “core food beliefs” and use these to guide their feeding choices.
The Health Pledge they propose we all take- “?I am responsible for my health and well-being and for that of the dogs in my care. I will become a knowledgeable advocate for myself and my dogs in all realms of life. I understand that life, healing, and health are always changing, requiring me to learn and evolve in order for me to become an effective advocate. I will not abdicate this responsibility to any person or doctor. The emotional and physical health of my dog rests in my hands.”
All of these quotes illustrate the concept I mentioned earlier, that decisions about health are ultimately all reflections of what we believe. It is not surprising that the authors selectively choose scientific “facts” that agree with their beliefs and ignore the rest, or twist and misinterpret and exaggerate scientific evidence freely if they give pride of place to personal belief and intuition. They certainly seem to hold firm opinions about how the world is, but at the same time they cling strongly to the incompatible idea that our beliefs somehow shape reality and to the Shakespearean dictum that “there is nothing either good or bad, but thinking makes it so.”
This allows them to have their cake and eat it too. They can present speculation or falsehoods as fact, reject facts regardless of the evidence, and still give their iconoclastic followers the freedom to do whatever “feels right” to them. It also allows them to present themselves as “experts” without any authentic expertise, because we are all experts if we read enough things that agree with what we already think!
It is an effective strategy for marketing ideas, but it has some disadvantages in terms of actually improving the health of our dogs. Reality exists, and it doesn’t much care what we think about it. If our intuitions or amateur understanding of complex scientific issues is wrong, our dogs may well suffer for it. As frustrating as it is to wait for reliable evidence before acting on promising new ideas, it has proven to yield much better results in the long run.
There is also another danger to the idea that we should all become “experts” and take full responsibility for the health of our pets. This view fosters the illusion that reality is always predictable and controllable, and that when things go wrong there is someone to blame. Owners often blame themselves when their pets fall ill, usually without good cause. This causes significant unnecessary suffering.
Owners may also be led into blaming someone else, whether the company that sold them dog food or the vet that gave their dog vaccinations or flea control products. The idea that chance or factors beyond our control cannot be responsible means we must always blame something or someone, regardless of how flimsy the evidence for their guilt may be. This leads not only to more unnecessary suffering for people (including many vets abused by distraught and angry clients), it also leads people to avoid healthcare interventions that actually do much more good than harm.
The illusion we may get of having control over reality and the frightening things than can happen to our pets when we take on complete responsibility for their health and buy into the belief that every negative outcome is preventable has a high price. Many comforting illusions do. Reality is more complex and unpredictable and less amenable to our desires than this book presents it to be. Fortunately, it is also less terrifying and “toxic” than they claim.
One of the most common medicines used by veterinarians is metronidazole. Though labeled as an antibiotic, like most drugs metronidazole has multiple effects. In addition to killing some bacteria, it can be used to treat the protozoal parasite Giardia, and it has a variety of anti-inflammatory and immunomodulatory effects. However, it is primarily used to treat diarrhea.
Like many alternative therapies I write about, metronidazole is widely used on the basis of primarily anecdotal experience. Most vets will tell you they have given it to dogs with diarrhea and seen the diarrhea stop, convincing them that the drug is beneficial. However, while it is certainly a more plausible remedy than some (e.g. homeopathy), the exact mechanism by which metronidazole should resolve diarrhea isn’t clear. The impact of the drug on the microbial flora of the gastrointestinal tract or effects on immune function might explain any benefits, but this is pretty theoretical.
Despite the fact that most vets should know better, anecdotal clinical experience is pretty persuasive. Of course, we all realize that most cases of diarrhea in which a specific cause, such as a parasite or underlying disease, is not found are cases that are going to get better no matter what we do. The use of metronidazole is very often mostly to placate pet owners tired of dealing with diarrhea and unwilling to wait a week or so for it to go away on its own, which it most often will.
Ideally, we would use metronidazole and all our other therapies on the basis of reliable controlled research evidence, but we don’t live in an ideal world. Such evidence is unavailable for many veterinary therapies, so we make the best judgement we can based on the evidence we have. Since self-limiting diarrheas in otherwise healthy dogs is not a cutting-edge medical research topic, for decades we have had to take our best guess about this treatment without good evidence.
A couple of years ago, I was excited to see a study looking at metronidazole for acute diarrhea in dogs. I wrote about the study, and summarized the other evidence for and against the use of metronidazole in diarrhea cases, in a Veterinary Practice News (VPN) column. The study found no difference in the time to resolution of diarrhea symptoms between metronidazole (4.6 days) and placebo (4.8 days). Dogs given a probiotic got better a little faster (3.5 days), but the difference was not statistically significant. This study suggested that metronidazole has little effect on the kind of mild, self-limiting diarrhea it is most often used to treat.
The finding for the probiotic was interesting, but also worth taking with a grain of salt. The overall evidence for probioticsin treating diarrhea is mixed, and it has proven much more difficult than proponents will admit to clearly prove they work. It is also interesting that the first two authors of this study are proponents of so-called “integrative medicine,” and there is a significant potential for bias here against pharmaceutical therapies and in favor of supposedly “natural” treatments like a probiotic.
After I wrote my VPN summary (but before it was published), another study of metronidazole for acute diarrhea in dogswas published. Since I only revisit recurring topics periodically, I hadn’t had a chance to look at it until recently. This study followed a broadly similar design, but with differences in the specific population of dogs studied and how they were included or excluded from the study groups. The results differed from the prior study in finding a marginally significant difference between the groups in the duration of diarrhea (metronidazole= 2.1 days, placebo= 3.6 days, p=0.04). Once again, the vast majority (about 89%) of dogs got better with no treatment, and the groups were quite small.
Overall, this study is more supportive of a benefit, but this is still pretty weak evidence, with fewer than 20 dogs treated and both statistically and clinically marginal effects for a condition that almost always goes away by itself. Undoubtedly, many owners would be happy to have a treatment that cut short the duration of their dogs’ diarrhea by a day and a half, assuming it was affordable (which metronidazole is) and safe (which it seems to be, though there is not extensive evidence for this either). The authors, as far as I can find, have conventional, science-based views of medicine.
So where does that leave vets in making decisions about the use of metronidazole for diarrhea? My own view is that the evidence for benefits is weak and inconsistent, that it is a plausible treatment but one for which we have to specific mechanism of action we can confidently credit for the supposed benefits, and it is used predominantly because of anecdotal experience, not strong research evidence. The drug is also used, in this context, for treating a mild and self-limiting condition. It has no obvious risks of harm to patients with the doses and time it is typically given, but the evidence for safety is no stronger than the evidence for efficacy.
As such, it shares a lot of characteristics with many alternative treatments.
If vets feel obliged to give owners something to try and relieve the symptoms of acute diarrhea in otherwise healthy dogs without parasites or another proven cause of diarrhea, using metronidazole may be reasonable so long as the lack of good evidence is disclosed to clients. Using probiotics is probably just as reasonable, with little to distinguish the two approaches from an evidence-based medicine perspective. Not treating at all once appropriate evaluation is done to rule out potential causes or more serious problems is probably the most reasonable thing to do, but it is unlikely many vets will be able to justify this to owners upset about their dogs’ symptoms.
I have written about Jean Dodds many, many times. She is one of those controversial figures who did some legitimate, even trailblazing work early in her career and then went off the deep end, not only embracing many forms of pseudoscience but apparently becoming convinced that she could never be mistaken regardless of the evidence against her ideas. She promotes speculative, inaccurate, and even clearly false claims about thyroid disease, pet nutrition, and vaccines. She has become especially blatant in selling proprietary diagnostic tests that, at best, are unproven and that, in some cases, have been clearly shown not to work. She has an undeserved reputation for being an “expert” in fields in which she is actually simply an outlier, promoting views that clash not only with the assessments of true experts but with basic science and research evidence.
Despite all of this, she has continued to practice and promote her unscientific approaches openly and with impunity for many years. Vets throughout the country, myself included, regularly have to try and explain to misinformed clients why her tests and recommendations are not reliable and shouldn’t be followed. And while holding this role as an iconoclastic sage for the alternative veterinary medicine movement, she has not held an actual license to practice in any state.
However, I have also discussed in the past the impotence of most legal and regulatory restraints on unscientific veterinary practice, with examples of figures such as Gloria Dodd and Al Plechner, arguably even more dangerous in their views and actions than Dr. Dodds, practicing openly without effective sanction for decades. With or without a medical license, many individuals are able to promote and sell pseudoscientific products and practices freely despite misleading and endangering the public because the political will does not exist to restrain them.
I was pleasantly surprised, then, to read in The Canine Review that the California Veterinary Medical Board has issued a cease-and-desist order and levied a fine on Dr. Dodds for practicing veterinary medicine without a license. The details of the citation involve Dr. Dodds being listed as the veterinarian of record on both electronic medical records and on results from her bogus Nutriscan allergy test and other laboratory tests.
Given the evidence of history, I am not sanguine that there will be any significant consequences for Dr. Dodds stemming from this action. Dr. Gloria Dodd was cited for malpractice and also issued a warning by the FDA for her quackery, and neither prevented her from continuing her actions. Dr. Plechner was being investigated by the veterinary medical board for a malpractice claim when he died, after decades of dangerous and unscientific practice, making the claim moot. I will not be at all surprised if Dr. Dodds manages to evade responsibility and continue her practices regardless of this action.
Nevertheless, at a minimum it is worthwhile to have an official regulatory body confirm what so many of us have known and discussed for years– that Dr. Dodds is not a trustworthy representative of the veterinary profession but an outlier whose views and conduct do not reflect the values or practices of the vast majority of her colleagues.
Today’s review is of my favorite book about aging so far, Steven Austad’s Why We Age: What science is discovering about the body’s journey through life. Dr. Austad’s style is clear and approachable, even a bit folksy. He creates the kind of engaging, personal narrative that Dr. Sinclair often achieved in Lifespan, but with none of the self-promotion. His explanations are easily understood without sacrificing accuracy or an acknowledgement of uncertainty.
Dr. Austad also takes an approach beloved by skeptics, explicitly stating his goal is to separate “substance and reasonable speculation from myth and wishful thinking.” He begins with ideas that are popular but not as accurate or powerful a representation of reality as often thought and then shows their limitations and the evidence against them. But he does an unusally effective job of this in that he creates authentically compelling stories for these ideas even when he ultimately debunks them. Often, he finds the useful bits of outdated theories and illustrates how they form part of a chain of reasoning and experimentation that leads forward, rather than reinforcing the narrative of science as a series of failures or flip-flops.
One of the myths he punctures is the notion of “special” populations of humans with unusually long lives. Often such populations are studies with an eye to understanding what makes them live so much longer than the rest of us. Austad shows that these pockets of exceptional longevity are based mostly on a combination of poor record keeping and excessive credulity. A strong correlation with lifespan turns out to be the literacy rate, since people who can’t read or keep accurate vital records can easily misremember or misrepresent their longevity.
The book also does a good job of challenging common assumptions and practices in the aging field. There is an interesting discussion of why lifespan itself isn’t a great measure of aging. We have extended average lifespan significantly by reducing causes of illness and death in children, but that hasn’t really changed the rate at which we age or affected maximum lifespan much. Lifespan and disease incidence may both be confounded by factors other than biological aging per se.
The age-specific mortality doubling time might be a better measure of the impact of specific interventions on the rate of aging, even if extended lifespan and healthspan are the real-world outcomes we are seeking. And given that reduction of specific causes of mortality individually have fairly small effects on lifespan, focusing on the rate of aging and measuring it accurately is critical.
Dr. Austad also introduced me to my new favorite phrase: “testosterone dementia.” In a cogent discussion of the evolution of aging, he touches on sex differences in mortality and longevity. One feature of this that readily appears is the increased non-disease-related mortality of young males, in humans, certainly, but in many other mammals as well. Often this involves behavioral risk factors, and as someone who cringes at memories of my youthful risk-taking, I appreciate the humorous but apt description of this particular sex-associated behavioral pattern.
Why We Age ends with a review of popular proposed methods for retarding aging and the state of the evidence for these. The book was written in 1997, so this is not entirely up to date, but it is still an excellent example of skeptical optimism—evaluating proposed interventions in a critical, evidence-based way even when one is personally hopeful about them.
The age of the book is one of its few weaknesses. Additionally, there is a rather long chapter on the subject of menopause, which includes some conclusions not consistent with current evidence-based guidelines. While the subject of reproductive senescence is an interesting and important one, this section hasn’t aged as well as the rest of the book.
On the whole, however, this is an excellent introduction to aging biology for the general reader: readable and engaging, accurate without being excessively detailed, skeptical yet positive, and much less focused on the personality and achievements of the author than the others I have reviewed.