What are Screening Tests, and Should You Use them?

What is Screening?
Screening is the use of diagnostic tests in apparently healthy individuals with no clinical symptoms.1-2The purpose is to detect asymptomatic disease with the presumption that this allows earlier, more effective intervention and will reduce suffering and delay or prevent death. 

Screening is widespread in human medicine, though it is increasingly a subject of controversy and debate.3Large-scale programs in human medicine to promote testing for specific diseases have been widely used, such as prostate-specific antigen (PSA) testing for prostate cancer and mammography for detection of asymptomatic breast cancer. These are examples of screening programs which are now being questioned and scaled back in light of better evidence concerning their risks and benefits.4-5

However, any diagnostic test employed in an individual with no clinical symptoms of illness is a screening test. In veterinary medicine, there are few large-scale, coordinated screening programs, but routine well-pet exams are a common screening practice. There are also calls for more extensive and intensive screening efforts, such as the recent guideline from the American Animal Hospital Association (AAHA) and the large diagnostic laboratory IDEXX promoting routine lab testing for nearly all pets.6

How Does Screening Benefit Patients?
Most veterinarians understand the potential benefits of screening. Individual patients will benefit if a disease is identified which can be treated more effectively when asymptomatic than at a later stage. Some diseases can be delayed or even cured if treated at an early stage which cannot be so effectively managed if not detected until there are clinical symptoms. Identifying IRIS Stage 2 Chronic Kidney Disease and instituting dietary therapy is an example of effective screening and intervention.7-8This is what most of us assume all screening accomplishes.

True negative results might be considered beneficial as well in that they provide reassurance and, depending on the tests involved, potentially a baseline value that can be used for diagnostic purposes in the future, even though they don’t directly impact morbidity or mortality.

When Is Screening Not Beneficial to Patients?
Screening is of no benefit if it fails to detect disease that is present (false negative results), if it detects disease that is not present (false positive results), if it detects disease that is indolent and would not ever cause clinical symptoms (overdiagnosis), and if it detects disease for which treatment is not effective or no more effective than it would be if the disease had not been identified until the symptomatic stage.

When Does Screening Harm Patients?
Screening is harmful when patients are given an incorrect diagnosis. False positive results create anxiety and discomfort and often incur risk and cost from additional testing or treatment for a disease which does not exist. False negative results provide reassurance when there actually is a disease present, which can delay truly beneficial diagnosis and treatment. 

Even correct diagnoses can cause harm.9-10The distress associated with a diagnosis of cancer in an asymptomatic patient, for example, is not counterbalanced by any benefit if there is no effective treatment. The patient simply lives longer knowing they have an illness they cannot treat. And overdiagnosis, the correct identification of disease that is non-progressive and does not lead to illness, exposes patients and owners to the risks and costs of the initial diagnosis and any further testing and treatment without any potential benefit from intervention. Patients may perceive a benefit from false positive results or from knowing about and treating indolent disease, but objectively this can only cause harm.11-13

How Do We Evaluate the Risks and Benefits of Screening?
It is rarely possible to know if screening has been beneficial or harmful for a particular individual because the outcome in the absence of testing cannot be known. Patients, pet owners, and clinicians nearly always feel as if testing is worthwhile even when not objective benefit can be demonstrated. True negative and false negative results are always reassuring, and if disease develops later there is rarely any recognition that these results may have delayed identification and treatment of it. Even if a false positive test is later shown to be false by further evaluation, many people experience such relief at the eventual result that they are grateful for the screening even though objectively the cost and discomfort associated with it have no possible benefit. Subjective evaluation of screening, then, nearly always supports it, but this is a limited and unreliable measure of the value of such testing.

Statistical evaluation of specific tests can be useful. The well-known parameters of sensitivity and specificity tell us something about the reliability of tests. However, the parameters of positive and negative predictive (PPV and NPV) value are arguably more important clinically. These are a function not only of the tests but of the prevalence of the disease we are testing for. If the majority of the population does not have the disease (as is usually the case with screening of asymptomatic individuals), the PPV will be quite low and most positive results will be false positives. Since most patients diagnosed through screening don’t actually have that disease they are tested for, the overall risks and costs of screening and follow-up testing or treatment may outweigh the benefits even if some individual patients are helped.14

The most accurate way to determine whether more patients benefit or are harmed by screening is through epidemiologic data regarding specific diseases and the outcome of screening and treatment.1-3,10-11,15Data on large populations has shown, for example, that most prostate cancer detected by PSA testing is nonprogressive. While some individuals do benefit from early detection, statistically many more undergo psychological distress (including a rise in heart attacks and suicide) and physical harm (such as incontinence, impotence, and even death) due to testing and treatment. PSA screening is no longer recommended as widely as it once was because such evidence shows the practice does more harm than good.4,9-10Similar evidence has led to reduced use of mammography and many other screening tests in humans.5, 9-10

Unfortunately, there is little data and awareness of this issue in veterinary medicine, and screening is widely viewed as an unqualified good. For example, the recent AAHA/IDEXX effort to encourage more laboratory testing of asymptomatic individuals never mentions overdiagnosis and suggests that even normal results or abnormal findings of no clinical significance should be “celebrated” and treated as useful information.6Screening is frequently promoted as a marker of high-quality, effective medicine.16-19The financial benefits of screening, to veterinary practices and companies that provide testing services, are also often mentioned as a benefit,6without any discussion about the issue of veterinary healthcare costs and the potential impact of this on availability of care.20-21

There is little evidence that screening improves outcomes such as quality of life or mortality in veterinary patients for most conditions. Research shows that testing of asymptomatic individuals often finds abnormalities and that some of these lead to potentially beneficial intervention.6,9However, few studies have looked at costs and risks of screening or gathered objective data on the balance between these and the potential benefits.

Bottom Line
“All screening programmes do harm; some do good as well, and, of these, some do more good than harm at reasonable cost.” (Gray et al, 2008)22The challenge for veterinary medicine is to recognize the potential harms of screening and to actively collect evidence to identify the risks and benefits of specific tests in specific populations. The current approach of assuming the theoretical benefits of screening must apply and that harms are negligible is not consistent with the evidence from human medicine and not a cost-effective, evidence-based approach for improving the welfare of our patients.

 The Power of Stories
Anecdotes are the primary justification for screening in veterinary medicine. The AAHA/IDEXX protocol, for example, includes a section called “The Power of Stories” which provides anecdotes of patients who benefitted from screening tests. Apart from not being an objective measure of the balance between risks and benefits, anecdotes can just as easily be used to challenge screening as to defend it. Here are two brief examples. 

Case Example: 10 Year-old Whippet
The patient presented for an annual examination and was offered a CBC and chemistry panel. Thrombocytopenia was identified, as well as mild neutropenia, elevated amylase, and decrease AST and CPK. Follow-up testing confirmed thrombocytopenia, and the patient was referred for further testing. Tick-borne disease panel, abdominal ultrasound, and thoracic radiographs were unremarkable. A subsequent CBC was unchanged, and pathology review concluded the findings were likely normal for the individual and breed. Despite the lack of any preceding or subsequent clinical illness, the owner experienced great distress at the possibility of serious illness in her pet, and the patient was exposed to the discomfort of numerous diagnostic procedures at a total cost of $924. 

Case Example: 5 Year-old Labrador Retriever
The patient presented with acute-onset lameness in the left hind leg and no other symptoms. Physical examination identified acute cranial cruciate ligament rupture. Pre-anesthetic chemistry panel revealed moderate elevation of ALT. Abdominal ultrasound identified mildly hypoechoic, indistinct nodular foci in the liver. Ultrasound-guided biopsy identified benign nodular hyperplasia. The patient died of hemorrhage following the biopsy. 

References
1. Wilson JMG. Jungner G. (1968) Principles and practice of screening for disease. World Health Organization Public Health Papers #34. Geneva, Switzerland.

2. Speechley M. Kunnilathu A. Aluckal E. et al. Screening in Public Health and Clinical Care: Similarities and Differences in Definitions, Types, and Aims – A Systematic Review. Journal of Clinical and Diagnostic Research. 2017;11(3):LE01-LE04.

3. Bulliard JL. Chiolero A. Screening and overdiagnosis: Public health implications. Public Health reviews. 2015:36(8). 

4. Tabayoyong W, Abouassaly R. Prostate Cancer Screening and the Associated Controversy. Surg Clin North Am. 2015 Oct;95(5):1023-39. 

5. Berry DA. Breast cancer screening: controversy of impact. Breast. 2013 Aug;22 Suppl 2:S73-

6. American Animal Hospital Association. Promoting preventative care protocols: Evidence, enactment, and economics. 2018. Accessed September 21, 2018. Available at: https://www.aaha.org/public_documents/professional/resources/promoting_preventive_care_protocols.pdf

7. International Renal Interest Society. IRIS staging of CKD. 2017. Accessed September 21, 2018. Available at: http://www.iris-kidney.com/pdf/IRIS_2017_Staging_of_CKD_09May18.pdf

8. Ross SJ, Osborne CA, Kirk CA, et al. Clinical evaluation of dietary modification for treatment of spontaneous chronic kidney disease in cats. J Am Vet Med Assoc. 2006 Sep 15;229(6):949-57.

9. McKenzie, BA. Overdiagnosis. J Amer Vet Med Assoc. 2016;249(8):884-889.

10. Welch HG, Schwartz LM, Woloshin S. Overdiagnosed: mak­ing people sick in pursuit of health. Boston: Beacon Press, 2011.

11. Raffle AE. Gray JAM. Screening: Evidence and Practice. Oxford: Oxford University Press, 2007. 

12. Boone D. Mallett S. Zhu S. et al. Patients’ & Healthcare Professionals’ Values Regarding True- & False-Positive Diagnosis when Colorectal Cancer Screening by CT Colonography: Discrete Choice Experiment. PLoS ONE 2017;8(12): e80767. 

13. Brodersen J, Siersma VD. Long-Term Psychosocial Consequences of False-Positive Screening Mammography. Annals of Family Medicine. 2013;11(2):106-115.

14. Maxim LD, Niebo R, Utell MJ. Screening tests: a review with examples. Inhalation Toxicology. 2014;26(13):811-828. 

15. Gates TJ. Screening for cancer: concepts and controversies. Am Fam Physician. 2014 Nov 1;90(9):625-31.

16. Lewis HB. Healthy pets benefit from blood work. Ban­field Data Savant. Accessed September 21, 2018. Available at: www.banfield.com/getmedia/1216c698-7da1-4899-81a3-24ab549b7a8c/2_1-Healthy-Pets-benefit-from-blood-work.

17. Irwin J. Do tests first: pre-surgical blood work may eliminate variety of surprises. DVM 360 Nov 1, 2003.

18. IDEXX Laboratories. Preanesthetic testing: don’t compro­mise—change happens fast. Accessed September 21, 2018. Available at: www.idexx.com.au/smallanimal/inhouse/preanesthetic-testing.html

19. Ward E. Ask the expert: preanesthetic testing in private prac­tice. NAVC Clinician’s Brief. January 2010. Accessed September 21, 2018. Available at: https://www.cliniciansbrief.com/article/preanesthetic-testing-private-practice

20. LaVallee E, Mueller MK, McCobb E. A Systematic Review of the Literature Addressing Veterinary Care for Underserved Communities. J Appl Anim Welf Sci. 2017 Oct-Dec;20(4):381-394.

21. Stull JW. Shelby J. Bonnett B. et al. Broadening access to veterinary care: Barriers and next steps to providing a spectrum of effective healthcare to our patients. J Amer Vet Med Assoc. 2018. In press

22. Gray JAM, Patnick J, Blanks RG. Maximising benefit and minimising harm of screening. British Medical Journal. 2008;336(7642):480-483.

Posted in Science-Based Veterinary Medicine | 39 Comments

Should we be Vaccinating Dogs at Acupuncture Points?

A couple of recent articles by acupuncturists have suggested that giving vaccines at acupuncture points may be more effective than giving them in other locations. This is clearly an attempt to demonstrate the serious, scientific legitimacy of acupuncture. However, there are a number of serious problems with these claims and with the studies used to support them. 

Study 1
Jin H, Xu Y, Shi F, Hu S. Vaccination at different anatomic sites induces different levels of the immune responses.Res Vet Sci. 2019;122:50-55. doi:10.1016/j.rvsc.2018.11.005

The Study
This study vaccinated rats with a live attenuated combination vaccine for dogs containing antigens for canine distemper, canine parvovirus, canine parainfluenza, canine adenovirus, and rabies. The rats were injected at several different anatomic locations (see Figure 1). A group of 10 female Rottweiler puppies between 32-36 days old were also vaccinated twice, three weeks apart, first with a modified live distemper/parvo vaccine and then with a modified-live vaccines for distemper, parvovirus, adenovirus, and parainfluenza. These vaccines were given at different locations in different dogs (see Figure 1). 

Figure 1

The study measured blood antibody levels as a marker of vaccine response. The rats were vaccinated twice, 2 weeks apart, and blood was collected at 2, 4, and 6 weeks after the second vaccination. The dogs were vaccinated twice, with different vaccines, three weeks apart. Blood was collected from the dogs 2, 4, and 6 weeks after the second vaccination. The levels of antibodies detected at each time period following vaccination at the different locations in the rats and dogs are shown in Figures 2 and 3.

Figure 2
Figure 3

Analysis of the Study
Methodologically, this study lacks a number of important features to control for error and bias. There was no randomization of subjects, no blinding of investigators or caregivers to the different treatments, and only a small number of dogs of one sex and breed were included. Such controls are especially important given that the study was funded by a veterinary acupuncture group with a clear interest in the outcome. It is also unclear what relevance the immune response of rats to injection with canine vaccines might have to the effect of those vaccines in protecting dogs from infectious diseases.

The dogs in the study were initially vaccinated at about 4 weeks of age, which is earlier than recommended because most puppies will have maternal antibodies at this age that interfere with the effect of vaccination. The second vaccine they received was at about 7 weeks of age, which is still slightly earlier than typically recommended. It is unclear whether these puppies had nursed or had maternal antibodies to begin with, but generally vaccination is done repeatedly between 8 and 16-20 weeks to ensure an adequate immune response. 

It is also unclear whether the differences in antibody levels have any real-world significance. With only a couple of exceptions, the levels were above or below the cutoff for all dogs in all groups at each time point. All dogs achieved antibody levels above the cutoff by about 11 weeks of age, well before the end of the usual vaccine series, so there is little reason to think the differences measured have any implications for susceptibility to disease, which is the import thing in any immunization program. There were also no adverse events for any of the dogs, so there is no reason to think the location of vaccination influences safety or effectiveness of immunization. 

The fact that antibody levels different with the site of vaccination is interesting. There has been some research in humans suggesting that the anatomic location of vaccination can influence the strength of the response.1-2This is suspected to be due to differences in blood supply, fat density, presence of immune surveillance cells, and other such factors. However, what, if anything, this has to do with acupuncture is a different question. For one thing, as I have discussed in detail in the past, there is little compelling evidence that acupuncture points exist at all as distinctive anatomic or functional locations. There is also significant variation in where acupuncturists locate such points, suggesting the concept is more a metaphor than a biological reality. 

In this study, the highest antibody levels were detected at the huohaiacupuncture point (also known as GV 1). This is a sensitive spot between the dorsal edge of the anus and the ventral tail base (see Figure 1). There likely are differences in the activity of the immune system between such a protected spot located close to an obvious source of bacteria and a location like the nape of the neck, a spot fortified against attack with thick skin and subcutaneous fat, little blood supply, and far from any excretory organs. There are plenty of distinctions between such locations that are far more plausible than the mystical notions of energy channels, Ch’i, Yin and Yang, and the other ideas that form the theoretical structure of Traditional Chinese Medicine. Any difference that might be found between the immune response at these spots does not require us to accept the reality of such folk mythology as the only explanation.

Study 2
Perdrizet JA, Shiau D-S, Xie H. The serological response in dogs inoculated with canine distemper virus vaccine at the acupuncture point governing vessel-14: A randomized controlled trialVaccine. 2019;37(13):1889-1896. doi:10.1016/j.vaccine.2018.10.076

The Study
100 client-owned dogs were randomly assigned (though by an odd method with some potential for umasking) to be vaccinated with a modified-live vaccine containing antigens for canine distemper, adenovirus, parvovirus, and parainfluenza at either the side of the neck or at the GV-14 acupuncture point (dorsal midline cranial to the dorsal spinous process of T1). Antibody titers for canine distemper were measured at the time of vaccination and 2 weeks later for all dogs.

Analysis of the Study
The dogs in both groups were vaccinated about a year after previous vaccination, which is earlier than the 3-5 years typically recommended, and both groups had both measurable antibody levels before vaccination and an increase in these levels after vaccination. There was tremendous individual variation in antibody titers and response to vaccination (Figures 4 and 5). Whether there is a consistent and meaningful effect of location of immune response is difficult to tease out of this background variation. The authors did some transformations and various statistical manipulation of the data to identify a statistically significant difference. Whether this is a true difference or a function of the particular study and the methods used is unclear.

Figure 4. Antibody responses to vaccination in different sites
Figure 5. Change in antibody titers after vaccination in different sites.

It is also unclear if there is any real-world difference in the protection against disease between these groups, a fact the authors acknowledge. Even if the location of vaccination predictably influences the magnitude of immune response, most dogs will be protected either way and a small proportion will not be protected either way, so is there any meaningful difference in the chances of dogs becoming ill? That is not a question this study can answer, but given how effective current vaccination is for core infectious diseases, it seems unlikely that changing the location in which we vaccinate is going to protect more dogs.

The authors imply that one reason to determine if vaccination at supposed acupuncture points might be worthwhile is that we could reduce the risks of vaccination if we generated a stronger or more durable response and, presumably, could then vaccinate less. This is implausible. For one thing, the disease they suggest result from vaccination, such as immune-mediated destruction of platelets or red blood cells, have not been consistently or convincingly associated with vaccines.And if we were able to trigger a stronger immune response by vaccinating in a particular location, there is no reason to believe this would not also increase any risks associated with the vaccination response. No adverse events were reported for either group in this study (not surprisingly, since such reactions are uncommon, though it is also possible that dogs with a history of vaccine reactions simply were not included in the study since they may no longer be receiving vaccines). 

General Issues 
These studies do not make a convincing case for vaccinating dogs in supposed acupuncture points. The reasons for this include the following:

  1. The principles of Traditional Chinese Medicineare unscientific folk mythology, and there is no reason to believe any practice guided by these ideas is going to be equal to or superior to practices based on scientific principles.

  2. Despite thousands of years of use, and decades of research, it has not been convincingly shown that so-called acupuncture points exist at all, except as metaphorical concepts. Acupuncturists in different sects identify very different points, and studies show acupuncturists are highly variable and imprecise in their localization of points. No consistent evidence indicates that acupuncture points in general, or the specific points in these studies, have distinctive and relevant anatomic or functional differences from other locations not designated as “points” by the TCM mythology.

  3. The variability in antibody levels and immune response may well be influenced by the location of vaccination. However, any such effect is more likely to be explained by objective and conventional anatomic and functional features of these locations, not by their status as special locations in terms of folk metaphors.

  4. There is great individual variation in antibody levels and immune response to vaccination, and it is unclear whether the statistical differences identified in these studies represent real differences, study artefacts, or normal variability. There is a growing recognition that statistical significance testing is misused in medical research and readily creates the impression of meaningful biological difference where none exists. This awareness has led to calls from statisticians and researchers to abandon the practice and emphasize more meaningful measures of effect in research studies.

  5. Even if it were established that there were true differences between the groups in these studies, from whatever cause, it has yet to be established that these have any real-world significance in terms of protection from disease or safety. Current vaccination practice are incredibly safe and effective, and while improvement is always desirable, the small differences seen in these studies are unlikely to have any implications for the actual health of patients. Certainly, nothing in this research suggests the locations chosen by the authors are safer or more effective at presenting disease than current locations typically used.

  6. From the practical perspective of a clinician actually treating dogs, I can tell you that vaccinating routinely at GV-1 (just above the anus) is going to be far more painful and difficult than current locations. Without a large, proven benefit to doing so, it makes no sense to subject patients or staff to this practice. 

Interestingly, the least antibody response seen in the Jin study was at a location very close to the GV-14 point used in the Perdrizet study. While I’m sure the authors would argue that these points are not comparable because of the precise localization of acupuncture point, again the research indicates that such points are in fact quite variable and imprecise, so to a small extent these studies actually contradict one another in terms of the effect of vaccination over the shoulders.

Bottom Line
There is no plausible reason to think that vaccinating dogs at supposed acupuncture points, if these even exist, will improve the protection from disease conveyed by vaccination or will reduce the risks of vaccinating.

References

  1. Jin H, Xu Y, Shi F, Hu S. Vaccination at different anatomic sites induces different levels of the immune responses. Res Vet Sci. 2019;122:50-55. doi:10.1016/j.rvsc.2018.11.005

  2. Shaw FE, Guess HA, Roets JM, et al. Effect of anatomic injection site, age and smoking on the immune response to hepatitis B vaccination. Vaccine. 1989;7(5):425-430. http://www.ncbi.nlm.nih.gov/pubmed/2530717. Accessed April 8, 2019.
Posted in Acupuncture | 6 Comments

Herbalists Petition for Specialty Recognition is Rejected

I recently updated my coverage of attempts by the American College of Veterinary Botanical Medicine (ACVBM) to attain specialty recognition, and explained why I am opposed to this effort. The deliberations and decisions of the American Board of Veterinary Specialties (ABVS) are shrouded in mystery and seldom discussed publicly, but I have been able to confirm that the ABVS has rejected the ACVBM petition. While I am hopeful that appropriate scientific study will find useful treatments buried in the pile of accumulated tradition and anecdote that currently makes up veterinary herbal medicine, I believe the ACVBM is not the organization to lead this effort, and I think the ABVS decision is in the best interests of animal patients.

Posted in Herbs and Supplements | 5 Comments

A Detailed, Evidence-based response to Petco’s Ban on “Artificial” Food Ingredients

Here is an article from Veterinary Practice News responding to the ridiculous marketing ploy by Petco declaring a ban on “artificial” food ingredients.

Since the late 1980s, individuals and organizations have been trying to warn the public about a deadly chemical known as DHMO. Though widely used in the home and in commercial settings, including the healthcare industry, this substance has been shown to cause severe lung damage and even death if inhaled in small quantities. Hundreds of thousands of people die annually from this cause.1

DHMO can also cause electrolyte disturbances and potentially fatal neurologic symptoms when taken orally, and it can cause severe burns and even explosions when heated.2A number of surveys have found high levels of support for banning DHMO, and elected officials in several countries have explored taking such action, but DHMO remains ubiquitous.3,4

Given the obvious dangers of this chemical, why do public health agencies not take action to restrict it? It is possible that funding and political influence from industry impedes regulatory action. However, it is more likely that governments have chosen not to ban DHMO because it is essential for life. Most people are surprised to learn this until they recognize the non-technical name for this chemical—water.

The campaign against DHMO (dihydrogen monoxide) has been used as a humorous illustration of the problem of chemophobia or chemonoia. These terms refer to the potent and widespread fear of anything labeled a “chemical.”5–7Nonscientists often assume that chemicals are inherently dangerous, even though the word properly refers to nearly every substance we encounter in daily life, from the deadliest poison to the basic necessities of life and even the materials that makes up our own bodies.

A concept integral to chemophobia is the Appeal to Nature Fallacy, the misconception that substances which occur naturally are inherently healthy and safe while those produced by humans, even if chemically identical to natural substances, are dangerous. Of course, it is easy to find examples that belie this notion. Nothing could be more natural than the E. colior Salmonella. Radioactive uranium, asbestos, and cyanide are completely natural. 

In contrast, the vaccines which have eliminated smallpox and polio are undeniably artificial. Antibiotics, synthetic vitamin supplements, blood transfusions, organ transplants, prosthetic limbs, insulin for diabetics, and even such simple and unheralded public health technologies as indoor plumbing and toilet paper have saved lives and reduced suffering for millions. Yet these are not “natural” in the usual sense of the word. 

Unfortunately, chemophobia and the Appeal to Nature Fallacy are widespread, and they often motivate pet care decisions. Some organizations and individuals take advantage of this by offering “natural” products or therapies and warning of the dangers of “chemicals” and anything “artificial.” A recent high-profile example of this exploitation of chemophobia is the announcement by Petco that the company “will not sell food and treats containing artificial colors, flavors and preservatives for dogs and cats.”8

The company’s public relations materials call this decision “a major step forward for pets” on “a momentous day.”8Petco effectively declares itself the arbiter of what constitutes healthy nutrition, even going so far as offering to “help pet parents affected by such a change to safely transition to a new food or brand that we believe is healthier for their pet” if customers are no longer able to buy a food they have been using.8Even though regulatory agencies and experts around the world have judged the additives on Petco’s list to be safe, the company has decided it knows better. 

The dramatic rhetoric in the Petco press materials may serve the purpose of creating a positive and profitable image for the company, but it obscures the danger of a marketing strategy that caters to unscientific reasoning and mostly unfounded fears. There is little in the way of scientific evidence, or even logical consistency, behind the Petco blacklist.9

For example, many of the “artificial” flavors and preservatives on the list occur naturally (see Table 1). Of course, the fact that these chemicals occur in nature doesn’t make them safe, just as flavors and preservatives are not necessarily unsafe if produced synthetically. However, the fact that Petco is banning naturally occurring substances for being “artificial” exposes the inconsistent logic behind this blacklist.

The health risks of most substances are related to the dose and route of exposure. And the risk of any substance should always be considered in relation to its benefits. Water is unsafe to drink only in very large quantities, but it is unsafe to breathe in even small amounts. It is also essential for life, taken at appropriate doses and by the appropriate route. The same logic, informed by scientific evidence concerning risks and benefits, should be applied to food additives, but Petco does not use this approach. 

Some of the substances on the list have no clear health implications. The color additives, for example, are almost certainly safe, but they serve no nutritional or health purpose.10,11,20–25,12–19These chemicals are added to pet food to appeal to the emotions and aesthetics of pet owners. While they serve no health-related purpose, banning these compounds is itself a way of appealing to the emotions of owners and their irrational fears, and there is no sound reason to believe this will benefit the health of pets.

For other items on the list, the impact of discouraging their use is less clear. Flavorings, for example, make nutritious and affordable commercial foods more palatable. Removing them may make it harder to provider appropriate nutrition to pets, and it may encourage owners to switch to homemade or other alternative diets that are often nutritionally inferior.26–31

The most clearly beneficial chemicals on the blacklist are the preservatives. Preventing spoilage, pathogen growth, and loss of nutrients in pet food is critical to providing healthy diets. In the absence of convincing evidence that commonly used and legally approved preservatives are actually harmful, removing them can only lead to less safe and healthy food for pets.

The evidence of health risks for most of the additives on the list is weak and based primarily on in vitroand lab animal studies that do not reliably predict the effects of normal use in pet foods. Most of these additives have been used for decades and reviewed periodically by regulators with no convincing evidence of negative health effects in humans or pets. Some may have risks that warrant removing them from use, but the evidence to make this case is lacking.

One can make the argument, of course, that any substance which has shown any hint of toxicity in lab animal studies ought to be avoided. There is little evidence, however, that this precautionary approach actually reduces harm. If the substances that are abandoned are actually safe, then there is no benefit. And there is always the potential that new, less thoroughly tested alternatives may have greater risks, even if they are “natural.”32

There is even evidence that some of the additives on the Petco list may actually have health benefits (see references from Table 1). Many have antiseptic, anti-inflammatory, anti-neoplastic, and antioxidant activity or other potentially beneficial uses. While the evidence for these effects is weak and based mostly on in vitroand lab animal studies, this is no less convincing than the evidence for negative health effects Petco has used to justify banning these compounds. 

Irrational and unscientific reasoning is not likely to lead to good healthcare choices. Unjustified fear of grains has led to grain-free diets making up about 25% of the dog food market. There is no reason to believe these diets have health benefits, and there are beginning to be signs that feeding these diets may be harming dogs.33–35The same reasoning that underlies this blacklist has also led Petco to sell raw diets, which have well-established health risks,28,36–42and to offer worthless homeopathic remedies43–47that pet owners may mistakenly substitute for effective, science-based medical treatment.  

The best way to protect our pets’ health is to rely on sound scientific evidence to help us weigh the risks and benefits of the food and medicine we provide, not to cater to irrational fears like chemophobia and meaningless distinctions such as “natural” and artificial.”  Table 1 provides a partial list of the sources, regulatory approvals, and evidence for safety and potentially beneficial effects of the items on the Petco blacklist. This is not a comprehensive review, simply an illustration that the items on this list are often “natural,” are judge by government experts around the world to be safe as used in food for humans and animals, and may have beneficial uses that offset any risk they may present. 

Veterinarians have a responsibility to support and educate pet owners and to challenge unscientific, fear-based marketing ploys like the Petco blacklist. The movement towards dangerous “natural” practices like feeding raw diets and avoiding vaccination is a real threat to animal welfare, and it is exacerbated by companies seeking market advantage through feeding and capitalizing on misconceptions and fear. 

References

1.        World Health Organization. Drowning.; 2018. https://www.who.int/news-room/fact-sheets/detail/drowning. Accessed December 24, 2018.

2.        DHMO.ORG. Facts About Dihydrogen Monoxide. http://www.dhmo.org/facts.html. Published 2018. Accessed December 24, 2018.

3.        DHMO.ORG Research Division. DHMO Research Reports. http://www.dhmo.org/research.html. Published 2008. Accessed December 24, 2018.

4.        Stuff.co.nz. National MP falls victim to water hoax. Stuff. http://www.stuff.co.nz/national/politics/38005/National-MP-falls-victim-to-water-hoax. Published 2009. Accessed December 24, 2018.

5.        Robson D. Chemonoia: The fear blinding our minds to real dangers. BBC FUture.

6.        Francl M. How to counteract chemophobia. Nat Chem. 2013;5(6):439-440. doi:10.1038/nchem.1661

7.        Ropeik D. On the roots of, and solutions to, the persistent battle between “chemonoia” and rationalist denialism of the subjective nature of human cognition. Hum Exp Toxicol. 2015;34(12):1272-1278. doi:10.1177/0960327115603592

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Posted in Nutrition | 20 Comments

Herbalists try again for medical specialty status.

In 2017 and 2018, I covered extensivelythe efforts of the American College of Veterinary Botanical Medicine (ACVBM) to achieve recognition as a medical specialty by the American Board of Veterinary Specialties (ABVS). I opposed recognition for several reasons:

  1. Prescribing of herbal medicine in the veterinary field is based mostly on folk medicine traditions, especially Traditional Chinese Veterinary Medicine (TCVM), which are mostly unproven and often deeply inconsistent with scientific medicine.

  2. Most herbalists, including leaders of the ACVBM, promote many alternative therapies other than herbal medicine, and these people often have medical philosophies inconsistent with science and science-based medicine.
  • Very few herbal remedies have been properly tested scientifically, so there is an insufficient foundation of knowledge to justify a specialty. What scientific work has been done in this area falls naturally under the domain of existing specialty organizations, such as the American College of Veterinary Clinical Pharmacology (ACVCP), so there is no need to create a new college.
  • Herbalism is not a recognized medical specialty in human or veterinary medicine in Europe, Australia, or the United States because it has not yet developed a legitimate scientific basis, and recognition of the ACVBM would give a misleading appearance of scientific legitimacy to a set of approaches reliant predominantly on folk traditions.

The ABVS tabled the ACVBM petitionand recommended the group seek subspecialty status under the ACVCP. The ABVS process is quite secretive, so little has been made public about it, but it appears that ACVCP wished to set up a methodical and careful process to consider any potential relationship between the groups, and the ACVBM decided it did not wish to pursue this process. Instead, the ACVBM has reactivated the tabled application for standalone recognition from ABVS. The latest version of the ACVBM petitiondiffers in some respects from the original petition submitted in 2016. The original petition, and subsequent communications with ABVS, tried to emphasize the mainstream, scientific nature of herbal medicine and downplay the alternative nature of the practice. The current petition does this as well, but it seems to emphasize more strongly the differences between a science-based approach to medicine and the philosophy of herbalism derived from traditional sources.

Here are a few examples:

Botanical medicine looks at pharmacognosy, not from the perspective of single molecule phytochemical discovery for the development of new drug leads, but rather to validate or understand traditional medicine and how the herbs work….That the whole plant is more therapeutic than a constituent is a fundamental principle of botanical medicine supported by research.

Principles of botanical medicine respect tradition as a source of empirical evidence that informs formal research design. The study of traditional use of plants within a culture is termed ethnobotany, and the study of traditional medicines is known as ethnomedicine, or ethnoveterinary medicine. Research may validate traditional uses.

Research may validate traditional use, or it may not (which is more common but not acknowledged in the petition). This statement clearly shows the unscientific view that the goal of research is to “validate or understand” the beliefs of traditional folk medicine, rather than to test them and find out if they are true or not. It also accepts as a central principle the traditional notion that whole plants are more effective than isolated plant compounds, though there is virtually no real-world research evidence supporting this idea.

The ACVBM differentiates themselves by interest in the rich knowledge base of traditional botanical medicine use and ethnobotany combined with modern scientific, chemical, toxicological, pharmacological clinical application and research in a practice that could be appropriately termed rationale phytotherapy to distinguish from colleagues who may only embrace traditional findings or who may eschew scientific findings…

This is encouraging, though given the background and other practices of the organizing committee for the ACVBM, I am not convince that the organization is likely to ever give priority to science over traditional knowledge if the two conflict. TCVM vets and practitioners of homeopathy and not really the most reliable guardians of science-based practice.

Veterinarians using botanical medicine have a patient centered approach, whereby the botanical medicines are selected based on the individual signs and pathophysiology as well as the diagnosis. So that two dogs with diabetes for example, may be treated with two different sets of botanical medicines. 

This is the common claim of alternative medicine to “individualize” therapy to a greater extent than scientific medicine. I’ve written many times beforeabout why this is a misleading and empty claim that hides the fact that such supposedly “individualized” therapies are almost never scientifically tested or shown to be effective or superior in any way to science-based practices.

The ACVBM also holds the philosophical position, common in alternative medicine, that tradition and personal or anecdotal experience are reliable and sufficient evidence and may even be superior to controlled scientific research. Here are some illustrations:

Sources of information include:

Traditional use. The bewildering variety of ethnoveterinary practices, ethnobotanical uses and folk practices around the world coupled with confounding aspects of cultural, placebo and other non-specific effects make reliable conclusions from any one tradition difficult. Frequently however, traditional use informs research and pharmacological activity is often found to be closely correlated. There are recurring themes in traditional medicine and persistent therapeutic approaches consistent with the use of “archetypal” chemical groups within plants.

I certainly agree that traditional use is inconsistent, low-quality evidence that has rarely led to definitive success in treatment. I disagree, however, with the claim that scientific evidence frequently confirms traditional use. Folk herbalism often uses plants for a wide variety of unrelated problems, and when properly tested the rare few uses which seem to have some real benefits are celebrated and the many that were useless are forgotten.

Collective clinical experience over decades. There is also the clinical experience of veterinary practitioners to consider- thousands of educated veterinary practitioners worldwide prescribe herbal medicines in their work. This has advantages of being in a modern veterinary context. Veterinary practitioners of botanical medicine have written texts and taught other veterinarians to achieve repeatable results within the botanical framework.

Collective clinical experience is another way of saying “anecdote,” and as the saying goes, the plural of “anecdote” is not “data.” The fact that people are “experts” in herbal medicine and have written and taught about it doesn’t, in itself, show that the beliefs and practices being passed along are correct or useful.

The third data source is substantial and scientifically sound but maybe not as clinically relevant to veterinary botanical medicine. The available published literature on phytochemistry and preclinical pharmacology…[this does] not however provide confirmation of a clinical effect; experience in practice is that the effect of the whole plant is rarely predicated on the effects of its parts….it is appreciated that herbs have been dismissed by many in the profession as the refuge of the uncritical. However, when all the sources of information come together and are integrated with pharmacological insights, something important happens; unique treatment strategies for treating notoriously difficult clinical problems become possible and the desire of the ACVBM is for animals to benefit from the efforts of this group to further develop the field. To be a fully effective therapy, it is not enough simply to know about the herbs themselves. Information must also be sought about how and when to use these herbs in response to various therapeutic challenges. Therapeutic approaches are different from those that underpin conventional medicine.

Again, this is a position that says scientific study, including pharmacological analysis of the compound sin plant remedies, is useful, but only as a supplement to the wisdom of tradition and personal experience, which still maintains without much evidence that traditional whole-plant remedies work better than plant-derived medicines. This is a pretty direct refutation of the principles of pharmacognosy (development of medicines from plants), which I suspect is a response to the rejection of the ACVBM by the ACVCP.

The universal role of plants in the treatment of disease is exemplified by their use in all the major systems of traditional medicine and ethnomedicine irrespective of their underlying philosophical premise.

So because lots of people have done it, this means it is worth doing? Not a rational perspective.

The practitioner of botanical medicine regards the whole formula or whole extract as the “active ” component” in the therapeutic context.

The concept of polyvalent or multifaceted activity of the medicine is central to botanical medicine – in the context of the advantage of chemical complexity -and even a single herbal extract is a natural multi agent medicine that can simultaneously target a range of desirable pharmacological effects.

The veterinary botanical practitioner prefers not just to prescribe chemically complex herbs, but often administers them in complex formulations, compared to conventional medicine preferring to prescribe a single drug. The practitioner chooses herbs or formulas for a cooperative or facilitating effect between the components to address therapeutic goals.

Again, these are tenets of faith, not scientifically proven propositions.

Philosophically the veterinary botanical medicine practitioner practices conventional medicine but overlays that practice with the use of botanical medicines in a framework of botanical principles to expand their options for treatment of disease and optimizing health.

Practitioners appreciate traditional knowledge as just one potential source of information, when coupled with published research and clinical experience, herbs can be prescribed safely and effectively.

This is the principle of “integrative medicine,” which holds that mixing the scientific with the unscientific and the proven with the unproven somehow makes the whole treatment approach better. As infectious disease doc Marc Crislip has put it, “If you integrate fantasy with reality, you do not instantiate reality. If you mix cow pie with apple pie, it does not make the cow pie taste better; it makes the apple pie worse.”

The ACVBM petition goes on to acknowledge that many veterinarians are concerned about the paucity of scientific research evidence concerning herbal medicine (though not to acknowledge directly that this is a well-founded concern). However, it then employs the tu quoquefallacy, arguing that since veterinary medicine as a whole suffers from a deficiency of high-quality research evidence, this should not be a barrier to treating herbal medicine as a legitimate scientific specialty. This misses the point, which is that we should be seeking more and better evidence, not giving up on the centrality of scientific research evidence to good medical practice. Giving the specialty imprimatur to an especially evidence-poor alternative practice only weakens the overall scientific basis of veterinary medicine.

An important basis of herbal medicine is the pharmacology and mechanisms of actions of plants and plant extracts, however they differ from drugs in their complexity, and in the underlying ethnomedical knowledge base used to initiate study of them. The botanical medicine diplomate can provide context to client and referring veterinarian inquiries, from both the ethnomedical and pharmacologic perspectives.

This basically suggests that the main reason herbalists should be considered specialists is that they can add the value of traditional knowledge to the scientific perspective on plant compounds. Again, this only makes sense if you presume, generally wrongly, that such traditional knowledge is useful or accurate much of the time.

Bottom Line

Nothing appears to have fundamentally changed in the ACVBM approach since I began to examine it in 2017. The ACVBM is a bit more direct in the latest petition in their claims that the primary reason they should be a distinct specialty group is because of their greater familiarity with traditional sources of knowledge about plant medicines. While they may acknowledge some need for scientific research into herbal remedies, they consistently claim that conventional veterinarians cannot effectively conduct such research without being familiar with the folk medicine approach to herbalism. 

This implies that scientists cannot test the effectiveness of any medical therapy without being experts in prescientific folk beliefs about it. Can we not evaluate surgery without being experts in bloodletting? Is the study of antibiotics to treat syphilis futile unless we have first-hand training in the use of the poison mercury for treating this disease? 

Ultimately, the ACVBM petition is simply another of the many efforts of alternative medicine to create an exception to the normal, scientific standards of evidence currently applied to medical practices. If scientific research works better than tradition or personal experience to determine which therapies are effective and why (and the evidence it does is overwhelming), then there is no need to give experts in folk medicine beliefs special status as experts in a discipline that can be readily and effectively studied with current scientific methods. 

I believe there is great potential for effective medical therapies in plant chemistry, and we have already realized this in many modern drugs. I also believe folk tradition has only very rarely stumbled across truly effective treatments through trial-and-error and anecdote, and it is not a particularly useful guide to which plants we should study for which problems. Those herbalists truly committed to a scientific medical practice should work within the accepted standards of scientific evidence to validate (or invalidate) specific herbal practices, rather than trying to create a group that will exist primarily to promote and self-validate their own alternative standards of evidence.

Posted in Herbs and Supplements | 4 Comments

Don’t Give Raw Milk to Your Pets!

A reader recently sent me a link to this little advertisement. 

This is an illustration of a popular bit of alternative nonsense, the idea that raw milk has magical health-giving properties. The idea owes a lot to the Appeal to Nature Fallacy, the idea that something “natural” is inherently. Safer and healthier than something “artificial.” Of course, those words have little real meaning since the distinction is arbitrary and unreliable. And in any case, the effects of such “natural” substances as Salmonella, Ebola, Uranium, asbestos, and many others make it pretty obvious that natural does not mean safe or health.

Like so many proponents of irrational nutritional ideas, raw milk promoters exaggerate, ignore, and misuse science to create the illusion that there is real evidence behind their claims. They also make free use of anecdotes which, as I have discussed many times, prove absolutely nothing.  The reality is that there is no reliable evidence that raw milk, from goats or any other species, has health benefits that can’t be obtained much more safely from pasteurized milk (that is, milk that has been heated to kill bacteria, parasites, and other dangerous microorganisms). 

If you feed your dog or cat raw milk, you are taking a serious risk of illness for your pet and yourself without any reasonable evidence to suggest a benefit that would make that risk worth taking. Just as raw diets in general have clearly established dangers and no proven benefits, so raw milk is a. poor bet with serious risks.  That is why raw milk products are generally illegalfor human consumption under federal and state law.

Here are some useful facts and resources to give you the real truth about the dangers of raw milk.

The CDC page on raw milk provides consumers with fact-based advice on the dangers and purported benefits of raw milk.

This organization collects information about raw milk and stories of families harmed by misguided belief in claims about raw milk.

Basnet S, Schneider M, Gazit A, Mander G, Doctor A. Fresh Goat’s Milk for Infants: Myths and Realities–A Review.Pediatrics. 2010;125(4):e973-e977. doi:10.1542/peds.2009-1906

Many infants are exclusively fed unmodified goat’s milk as a result of cultural beliefs as well as exposure to false online information. Anecdotal reports have described a host of morbidities associated with that practice, including severe electrolyte abnormalities, metabolic acidosis, megaloblastic anemia, allergic reactions including life-threatening anaphylactic shock, hemolytic uremic syndrome, and infections. We describe here an infant who was fed raw goat’s milk and sustained intracranial infarctions in the setting of severe azotemia and hypernatremia, and we provide a comprehensive review of the consequences associated with this dangerous practice.

Oliver SP, Boor KJ, Murphy SC, Murinda SE. Food Safety Hazards Associated with Consumption of Raw Milk.Foodborne Pathog Dis. 2009;6(7):793-806. doi:10.1089/fpd.2009.0302

An increasing number of people are consuming raw unpasteurized milk. Enhanced nutritional qualities, taste, and health benefits have all been advocated as reasons for increased interest in raw milk consumption. However, science-based data to substantiate these claims are limited. People continue to consume raw milk even though numerous epidemiological studies have shown clearly that rawmilk can be contaminated by a variety of pathogens, some of which are associated with human illness and disease. Several documented milkborne disease outbreaks occurred from 2000-2008 and were traced back to consumption of raw unpasteurized milk. Numerous people were found to have infections, some were hospitalized, and a few died. In the majority of these outbreaks, the organism associated with the milkborne outbreak was isolated from the implicated product(s) or from subsequent products made at the suspected dairy or source. In contrast, fewer milkborne disease outbreaks were associated with consumption of pasteurized milk during this same time period. Twenty nine states allow the sale of raw milk by some means. Direct purchase, cow-share or leasing programs, and the sale of raw milk as pet food have been used as means for consumers to obtain raw milk. Where raw milk is offered for sale, strategies to reduce risks associated with raw milk and products made from raw milk are needed. Developing uniform regulations including microbial standards for raw milk to be sold for human consumption, labeling of raw milk, improving sanitation during milking, and enhancing and targeting educational efforts are potential approaches to this issue. Development of pre- and postharvest control measures to effectively reduce contamination is critical to the control of pathogens in raw milk. One sure way to prevent raw milk-associated foodborne illness is for consumers to refrain from drinking raw milk and from consuming dairy products manufactured using raw milk.

Committee on Infectious Diseases, Committee on Nutrition, American Academy of Pediatrics. Consumption of Raw or Unpasteurized Milk and Milk Products by Pregnant Women and Children.Pediatrics. 2014;133(1):175-179. doi:10.1542/peds.2013-3502

Sales of raw or unpasteurized milk and milk products are still legal in at least 30 states in the United States. Raw milk and milk products from cows, goats, and sheep continue to be a source of bacterial infections attributable to a number of virulent pathogens, including Listeria monocytogenes, Campylobacter jejuni, Salmonella species, Brucella species, and Escherichia coli O157. These infections can occur in both healthy and immunocompromised individuals, including older adults, infants, young children, and pregnant women and their unborn fetuses, in whom life-threatening infections and fetal miscarriage can occur. Efforts to limit the sale of raw milk products have met with opposition from those who are proponents of the purported health benefits of consuming raw milk products, which contain natural or unprocessed factors not inactivated by pasteurization. However, the benefits of these natural factors have not been clearly demonstrated in evidence-based studies and, therefore, do not outweigh the risks of raw milk consumption. Substantial data suggest that pasteurized milk confers equivalent health benefits compared with raw milk, without the additional risk of bacterial infections. The purpose of this policy statement was to review the risks of raw milk consumption in the United States and to provide evidence of the risks of infectious complications associated with consumption of unpasteurized milk and milk products, especially among pregnant women, infants, and children.

LeJeune JT, Rajala?Schultz PJ, Rajala-Schultz PJ. Unpasteurized Milk: A Continued Public Health Threat.Clin Infect Dis. 2009;48(1):93-100. doi:10.1086/595007

Although milk and dairy products are important components of a healthy diet, if consumed unpasteurized, they also can present a health hazard due to possible contamination with pathogenic bacteria. These bacteria can originate even from clinically healthy animals from which milk is derived or from environmental contamination occurring during collection and storage of milk. The decreased frequency of bovine carriage of certain zoonotic pathogens and improved milking hygiene have contributed considerably to decreased contamination of milk but have not, and cannot, fully eliminate the risk of milkborne disease. Pasteurization is the most effective method of enhancing the microbiological safety of milk. The consumption of milk that is not pasteurized increases the risk of contracting disease from a foodstuff that is otherwise very nutritious and healthy. Despite concerns to the contrary, pasteurization does not change the nutritional value of milk. Understanding the science behind this controversial and highly debated topic will provide public health care workers the information needed to discern fact from fiction and will provide a tool to enhance communication with clients in an effort to reduce the incidence of infections associated with the consumption of unpasteurized milk and dairy products.

Langer AJ, Ayers T, Grass J, Lynch M, Angulo FJ, Mahon BE. Nonpasteurized dairy products, disease outbreaks, and state laws-United States, 1993-2006Emerg Infect Dis. 2012;18(3):385-391. doi:10.3201/eid1803.111370

Although pasteurization eliminates pathogens and consumption of nonpasteurized dairy products is uncommon, dairy-associated disease outbreaks continue to occur. To determine the association of outbreaks caused by nonpasteurized dairy products with state laws regarding sale of these products, we reviewed dairy-associated outbreaks during 1993-2006. We found 121 outbreaks for which the product’s pasteurization status was known; among these, 73 (60%) involved nonpasteurized products and resulted in 1,571 cases, 202 hospitalizations, and 2 deaths. A total of 55 (75%) outbreaks occurred in 21 states that permitted sale of nonpasteurized products; incidence of nonpasteurized product-associated outbreaks was higher in these states. Nonpasteurized products caused a disproportionate number (?150× greater/unit of product consumed) of outbreaks and outbreak-associated illnesses and also disproportionately affected persons <20 years of age. States that restricted sale of nonpasteurized products had fewer outbreaks and illnesses; stronger restrictions and enforcement should be considered.

Lucey JA. Raw Milk Consumption: Risks and Benefits.Nutr Today. 2015;50(4):189-193. doi:10.1097/NT.0000000000000108

There continues to be considerable public debate on the possible benefits regarding the growing popularity of the consumption of rawmilk. However, there are significant concerns by regulatory, or public health, organizations like the Food and Drug Administration and the Centers for Disease Control and Prevention because of risk of contracting milkborne illnesses if the raw milk is contaminated with human pathogens. This review describes why pasteurization of milk was introduced more than 100 years ago, how pasteurization helped to reduce the incidence of illnesses associated with raw milk consumption, and the prevalence of pathogens in raw milk. In some studies, up to a third of all raw milk samples contained pathogens, even when sourced from clinically healthy animals or from milk that appeared to be of good quality. This review critically evaluates some of the popularly suggested benefits of raw milk. Claims related to improved nutrition, prevention of lactose intolerance, or provision of “good” bacteria from the consumption of raw milk have no scientific basis and are myths. There are some epidemiological data that indicate that children growing up in a farming environment are associated with a decreased risk of allergy and asthma; a variety of environmental factors may be involved and there is no direct evidence that raw milk consumption is involved in any “protective” effect.

Posted in Nutrition | 9 Comments

SkeptVet Visits The Pet Doctor Podcast- Are we seeing more cancer in pets?

In October, I wrote a column for Veterinary Practice News (VPN) on the question of whether or not cancer is more common in dogs and cats now than it used to be. This is a core argument in the Truth About Pet Cancer propaganda video series I debunked HERE and HERE. The VPN article caught the attention of Dr. Bernadine Cruz, who asked me to visit her podcast to discuss the subject. Enjoy!

The Pet Doctor Podcast- Are we seeing more cancer in pets.

Posted in Presentations, Lectures, Publications & Interviews | 5 Comments

Crowdfunding Quackery

One of the most heartbreaking things we all see on social media are appeals for financial help to fund medical treatment. Especially here in the U.S., where healthcare is less readily available to low-income people than in most developed countries, it has become common to see crowdfunding campaigns raising money for medical care. It is inspiring that people are so often willing to help strangers with medical expenses, but it is sad and wrong that patients have to rely on such ad hoc methods for funding the care they need.

As sad as this inherently is, it becomes depressing and infuriating when these crowdfunding campaigns are intended to pay for unproven or quack therapies. Crowdfunding provides a new venue for people to be misled and exploited by proponents of untested, ineffective, and dangerous medical treatments, Now, not only the desperation of patients and their families are taken advantage of, but also compassion of well-meaning strangers who contribute to these campaigns.

Two recent studies have been published in the Journal of the American Medical Association (JAMA) investigating this issue, and these have been publicized through reporting by NPRand other media outlets.

Vox F, Folkers KM, Turi A, Caplan AL. Medical Crowdfunding for Scientifically Unsupported or Potentially Dangerous TreatmentsJAMA. 2018;320(16):1705–1706. doi:10.1001/jama.2018.10264

This study looked at homeopathyand naturopathyfor cancer, hyperbaric oxygen therapy,stem cell treatmentfor brain and spinal cord injury, and long-term antibiotics for Chronic Lyme Disease. All. But the last will be familiar to readers as examples of methods that are dubious or simply don’t work. The study found:

More than 1000 medical crowdfunding campaigns for 5 treatments that are unsupported by evidence or potentially unsafe raised more than $6.7 million… These results reveal that a wide scope of cam- paigns for unsupported, ineffective, or potentially dangerous treatments are moderately successful in obtaining funding. Assuming that the funds raised are spent to pay for these treatments, donors indirectly contributed millions of dollars to practitioners to deliver dubious, possibly unsafe care. 

Snyder J, Turner L, Crooks VA. Crowdfunding for Unproven Stem Cell–Based Interventions. JAMA.2018;319(18):1935–1936. doi:10.1001/jama.2018.3057

The second study focused specifically on stem cell therapies and found similarly large amounts of money committed to campaigns for questionable treatment and also misleading appeals to donors:


Our search identified 408 campaigns seeking donations for stem cell interventions advertised by 50 individual businesses. These campaigns requested $7?439?308 and received pledges for $1?450?011 from 13?050 donors.

Crowdfunding campaigns for unproven stem cell–based interventions underemphasize risks and exaggerate the efficacy of these interventions. These findings suggest that medical crowdfunding campaigns convey potentially misleading messages about stem cell–based interventions. These claims may be especially powerful when embedded within compelling personal narratives. 

As usual, there are no similar studies looking at how much crowdfunding there is for unproven and quack veterinary therapies, but it takes little time and effort to find such campaigns online:

Chi Chi’s Recent Medical Expenses

Chi Chi has an integrated treatment plan that includes both traditional and holistic treatments…Chi Chi takes a number of traditional and Chinese medications to manage her medical conditions… and regular Hyperbaric Oxygen Treatments

Help Give Cayman a Fighting Chance!

extensive therapies including laser, acupuncture

Paralyzed Rescue Dog – Pani

water therapy and laser therapy… cranberry supplements and probiotics…has also been recommended joint supplements

Grace’s Health Treatment?

the best course of treatment for quality of life and longevity is to go a TCM (Traditional Chinese Medicine) route.  With a combination of a fully holistic/organic diet, herbal supplements, chinese medicine and an aggressive 3-day Vitamin drip protocol

Of course, I don’t believe the people making these appeals are doing anything wrong. They desperately want to help the animals they love, and they are willing to ask for help even when that may be difficult for them to do. And those who donate to these campaigns are illustrating the best qualities of the human spirit, compassion and concern for not only friends and family but complete strangers. Most of the appeals I have seen, including those that\ mention alternative therapies, do describe appropriate, science-based medical care, so hopefully these animals are getting the real treatment they need to get well.

Unfortunately, the fact remains that these animal owners and the good Samaritans who help them are paying for treatments that are at best questionable and, in many cases, clearly do not and cannot work. Though the practitioners offering them likely do so believing they are helping, at some point being a healthcare provider should mean knowing better and being required to provide effective treatment. It is hard not to wonder how many pets are harmed by the false belief in these therapies, and how much effective medical care could be paid for with the money that goes to unsupported or quack therapies.

Posted in General | Leave a comment

Evidence Update: Grain-free and other “BEG” Diets Associated with Heart Disease in Dogs

I have been following with great interest the emerging evidence about grain-free and exotic protein diets as a possible risk factor for heart disease in dogs. I first raised the subject in response to several cases of dilated cardiomyopathy (DCM) I saw in my practice, and which became part of a study which has recently been published looking at the issue in this breed. There have been several other papers recently published touching on the relationship between diet and DCM in dogs, and I want to quickly discuss each of them

Freeman LM, Stern JA, Fries R, Adin DB, Rush JE. Diet-associated dilated cardiomyopathy in dogs: what do we know?J Am Vet Med Assoc. 2018 Dec 1;253(11):1390-1394. doi: 10.2460/javma.253.11.1390.

This is an excellent summary of what we know and don’t know about this issue so far. The bottom line is that a suspicious number of cases of DCM have been appearing in dogs eating what have been called BEG diets- boutique, exotic protein, grain-free. What this means is that diets without grains, diets with a high proportion of legumes, and diets with animal proteins that have not been traditionally used in dog food, and which consequently have not been studied as thoroughly in terms of their nutrient content and other factors, have been associated with DCM in a variety of breeds. This is not proof that the diets, or any particular characteristic of them, is causing this disease. Such proof will require different kinds of research studies. However, this is a potential warning sign that deserves to be acknowledged and followed up with appropriate research.

In some cases, the diets and disease has also been associated with a deficiency in the amino acid taurine. This is an amino acid that dogs do not normally require in the diet since they can make as much as they need. However, in some breeds there appear to be genetic factors that make individuals more susceptible to taurine deficiency, and associated heart disease. These may include reduced production of taurine, increased loss of taurine, or increased need for taurine. Certain diets that have low levels of the ingredients from which taurine is made or that contain substances, such as legumes and some types of. Fiber that make reduce absorption or synthesis of taurine and its precursors or that encourage taurine loss make act in con cert with these genetic factors to lead to deficiency and disease in some dogs. Many of the details in this hypothetical series of steps remain to be understood. 

An example of how this problem may work comes from another recent paper looking at golden retrievers with DCM, including several of my patients.

Kaplan JL, Stern JA, Fascetti AJ, Larsen JA, Skolnik H, et al. (2018) Taurine deficiency and dilated cardiomyopathy in golden retrievers fed commercial diets. PLOS ONE 13(12): e0209112. 

In this study, the dogs with DCM had taurine deficiency, and most were eating BEG diets. Changing the diet and supplementing taurine, along with other treatments, seemed to improve or cure the disease in most, but not all of the dogs.  Again, this was not a study designed to determine if the diets caused the taurine deficiency or the DCM, but the fact that all the dogs were on the diets that we are concerned about, and the fact that changing the diet and adding taurine, among other interventions, seemed to help most of these dogs, does make looking more closely at these diets worthwhile. It also makes it reasonable to consider avoiding these diets in golden retrievers, and perhaps other breeds known to have a higher-than-average risk of taurine deficient DCM even if we are not certain if the diets are the cause or, if so, how exactly that works.

It is important, however, not to get too fixated on taurine. Many of the dogs seen with DCM and eating BEG diets are not taurine deficient, so golden retrievers appear to be experiencing a different problem than these other breeds. It is possible that other aspects of these diets besides their effects on taurine levels could be a risk factor for DCM, and we know even less about how this might work.

This is illustrated by the third new study, which looked at dogs with DCM and evaluated the differences between those on grain-free diets and those on grain-based diets. 

DarcyAdin, Teresa C.De Francesco, BruceKeene, SandraTou, KathrynMeurs, ClarkeAtkins, BrentAona, KariKurtz, LaraBarron, KorinnSaker. Echocardiographic phenotype of canine dilated cardiomyopathy differs based on diet type.J Vet Cardiol. 2019;21:1-9.

In this group of dogs, grain-free diets were associated with some signs of more severe heart disease than that exhibited by dogs on diets containing grains, though the differences did not appear in all measures of heart disease severity. None of the dogs in this group were taurine deficient, so whatever the relationship between diet and DCM here, it had nothing to do with taurine.

The great deal we don’t know about DCM and diet is frustrating to all of us. We have to try and resist the temptation, however, to substitute our own beliefs and theories for the missing facts. Proponents of grain-free and other unconventional diets will point to the gaps in our knowledge as evidence that we can’t really blame these diets and that there is no need to change what they feed. While it is true that we can’t be certain what role, if any, such diets are playing in causing heart disease, the fact that they are consistently associated with DCM in several different groups of dogs is, at the least, reason for concern and further research. What is more, none of the claims for the health benefits of grain-free and other unconventional diets have any compelling scientific support, so there is no good reason to choose such diets even if the evidence for their potential risks are still very preliminary.

Bottom Line
We cannot say with certainty that BEG diets cause heart disease. We can only say that they have been associated with DCM in both golden retrievers with taurine deficiency and in other breeds without taurine deficiency. We can also say that changing diets appears to have benefitted some of these dogs, though many other treatments were employed at the same time, which limits out ability to know how important a factor this diet change was in the dogs’ recovery. 

We can also say that none of the claims for health risks from grains in pet foods, or for health benefits from grain-free or other BEG diets, are supported by any reasonable scientific evidence. Certainly, the evidence for such diets is weaker than even the very limited evidence against them. 

As pet owners and veterinarians, we need to proportion our confidence in any conclusions to the strength of the available evidence and be willing to change our minds as new evidence emerges. We also need to make our decisions now, even before we have perfect evidence. Right now, there is no solid reason to think grain-free diets have any health advantages, and there is weak evidence to suggest they might have health risks for some dogs. If you have a golden retriever, it seems reasonable to avoid the diets that have been associated with taurine deficiency and DCM in this breed. Even if you don’t have a golden, you should at least give some thought to why you might want to feed or avoid BEG diets. The evidence can’t make the decision for you, but it should certainly be considered.

Posted in Nutrition | 47 Comments

New Report on Complication Rates for Neutering Surgery in Dogs and Cats

I have written extensively about the subject of neutering (spaying and castrating male and female dogs and cats). The bulk of the discussion and debate about this procedure centers on the health effects. It is generally recognized to be a pretty safe procedure, though of course no surgery is entirely without risk. The scientific literature has limited information on the specific risks of the neutering surgery procedure itself and how often they occur.

Total complication rates for routine castration or spaying have been reported from 2.6%-33% of cases.The majority of these complications are minor and require no treatment. Complication rates vary considerably from practice to practice and are generally reported to be higher in studies of surgeries performed by students in training. Reported death rates are less than 0.1%.1-5

A new source of data on this subject has recently become available which represents the type of “Big Data” so popular these days. The Royal College of Veterinary Surgeons (RCVS) charity arm RCVS Knowledge,  has a program in place that collects information from practices around the country in a central database. The goal is to encourage clinical audit, a quality improvement process in which veterinary practices can investigate the outcomes for their patients and compare these with those of other practices or with an established “gold standard.” This facilitates recognizing processes that aren’t working as well as they could and improvement in patient care.

The RCVS has recently released the results of data collection on complications of neutering. Though not the result of a controlled, prospective research process, this audit report is based on over 30,000 individual surgeries, so it at least represents a potentially powerful source of data. The specific variables that affect outcome of neutering surgery in individual animals can’t be identified, and there is the problem of patients who can’t be followed and whose outcome is unknown. However, this type of data complements the research evidence already available and gives us a general sense of the complication rates in the UK for these common procedures.

Routine Neuter Complication Rates

The outcomes measured were cases with no complications, those with minor complications not needing treatment, problems needing medical treatment, problems needing surgical treatment, and fatalities. About 8% of the cases in the database were not available for followup, and these were not included in the calculation of complication rates.

Total Overall Complications

Outcome Frequency Percent Cum Percent
Abnormal but no treatment necessary 2795 9.3% 9.3%
Abnormal requiring medical treatment 2254 7.5% 16.8%
Abnormal requiring surgical intervention 341 1.1% 17.9%
Fatality of animal 29 0.1% 18.0%
No abnormality present 24627 82.0% 100.0%
Total 30046 100.0% 100.0%

 

Complications for Male Cats

Outcome Frequency Percent Cum Percent
Abnormal but no treatment necessary 56 1.4% 1.4%
Abnormal requiring medical treatment 53 1.3% 2.7%
Abnormal requiring surgical intervention 23 0.6% 3.3%
Fatality of animal 3 0.1% 3.4%
No abnormality present 3885 96.6% 100.0%
Total 4020 100.0% 100.0%

 

Complications for Male Dogs

Outcome Frequency Percent Cum Percent
Abnormal but no treatment necessary 977 11.4% 11.4%
Abnormal requiring medical treatment 796 9.3% 20.6%
Abnormal requiring surgical intervention 61 0.7% 21.3%
Fatality of animal 6 0.1% 21.4%
No abnormality present 6763 78.6% 100.0%
Total 8603 100.0% 100.0%

 

Complications for Female Cats

Outcome Frequency Percent Cum Percent
Abnormal but no treatment necessary 616 7.0% 7.0%
Abnormal requiring medical treatment 385 4.4% 11.4%
Abnormal requiring surgical intervention 163 1.9% 13.3%
Fatality of animal 5 0.1% 13.3%
No abnormality present 7596 86.7% 100.0%
Total 8765 100.0% 100.0%

 

Complications for Female Dogs

Outcome Frequency Percent Cum Percent
Abnormal but no treatment necessary 1146 13.2% 13.2%
Abnormal requiring medical treatment 1020 11.8% 25.0%
Abnormal requiring surgical intervention 94 1.1% 26.1%
Fatality of animal 15 0.2% 26.3%
No abnormality present 6383 73.7% 100.0%
Total 8658 100.0% 100.0%

 

These results are broadly similar to previously reported numbers, though lower than sometimes seen in studies in which inexperienced veterinary students are performing the procedures. They confirm that the procedure is very safe, that most complications are minor and do not require much, if any, treatment, and that mortality rates are very low. Females experience more complications because the surgery is necessarily more invasive. These data don’t tell us anything about the differences between specific neutering procedures, breeds, ages of patients, and many other factors, so they don’t let us predict the precise risk for individual patients. But they provide a general background that help us in making decisions about neutering.

 

References

  1. Pollari FL, Bonnett BN, Bamsey SC, Meek AH, Allen DG.Postoperative complications of elective surgeries in dogs and cats determined by examining electronic and paper medical records. Journal of the American Veterinary Medical Association 1996;208(11):1882-6.
  2. Howe LM. Short-term results and complications of prepubertal gonadectomy in cats and dogs. Journal of the American Veterinary Medical Association 1997;211(1):57-62.
  3. Pollari FL, Bonnettt B.N. Evaluation of postoperative complications following elective surgeries of dogs and cats at private practices using computer records. Canadian Veterinary Journal 1996;37:672-8.
  4. Burrow R, Batchelor D, Cripps P. Complications observed during and after ovariohysterectomy of 142 bitches at a veterinary teaching hospital. Veterinary Record 2005;157(26):829-33.
  5. Root Kustritz MV. Effects of surgical sterilization on canine and feline health and on society. Reprod Domest Anim. 2012 Aug;47 Suppl 4:214-22.

 

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