Canine Vaccine Hesitancy: The Fight Against Anti-vaccine Misinformation Goes On

For many years now, I have fought against the encroachment of anti-vaccine misinformation and fears into veterinary medicine. I have written blog posts and journal articles on the subject, and I’ve discussed vaccine hesitancy in podcasts, on YouTube, and at veterinary conferences. 

It has long been clear that some pet owners have been frightened by proponents of unscientific anti-vaccine ideas. They are exposed, like all of us, to misinformation from activists opposing vaccines for human use, such as disgraced former doctor Andrew Wakefield and the Disinformation Dozen, well-known sources of bad information such as Mercola, RFK Jr., and the Bollingers. Unfortunately, there is also no shortage of vets and others in the animal health world also contributing to excessive and harmful anxiety about vaccines in pets. Anecdotally, many vets feel that pet owners have become more hesitant about appropriate vaccination of their dogs and cats.

Now, we have a bit of research data that, unfortunately, reinforces this concern.

Motta M, Motta G, Stecula D. Sick as a dog? The prevalence, politicization, and health policy consequences of canine vaccine hesitancy (CVH). Vaccine. 2023 Aug 26:S0264-410X(23)01015-0. doi: 10.1016/j.vaccine.2023.08.059. Epub ahead of print. PMID: 37640567.

This study surveyed 2,200 adults in the U.S. and evaluated the presence of Canine Vaccine Hesitancy (CVH), defined as, “dog owners’ skepticism about the safety and efficacy of administering routine vaccinations to their dogs.” The findings were a clear warning to vets and other animal lovers about the danger of anti-vaccine misinformation and the importance of speaking up and providing the public with honest, reliable, fact-based information about vaccination.

As the authors state, “a large minority of dog owners consider vaccines administered to dogs to be unsafe (37%), ineffective (22%), and/or unnecessary (30%). A slight majority of dog owners (53%) endorse at least one of these three positions.” 

Also worrisome was the finding that 48% of dog owners opposed mandatory rabies vaccination and agreed with the statement, “The decision to vaccinate dogs that are kept as pets should be left up to individual pet owners.” This echoes powerfully the kind of anti-public health position that emerged to oppose vaccination for SARS-CoV-2, and which led to hundreds of thousands of unnecessary deaths from COVID-19 in the U.S. alone.

The study also looked at factors that might be associated with CVH. Endorsement of misinformation about human vaccines was a predictor of CVH, whereas a college education was associated with a lower risk of hesitancy about canine vaccination. 

These results, while depressing, are not surprising. We are in a period of significant mistrust and misinformation about science generally, and there is no reason to expect pet owners or veterinary medicine would be exempt from this problem. The study is also just a preliminary effort at assessing a complex and multifactorial problem. However, this first step at gathering real data about the issue of veterinary vaccine hesitancy is an important one. It should serve as a powerful warning to veterinarians and others who value animal welfare that we cannot afford to be complacent nor quiet. 

We need to advocate strongly and constantly for science-based pet healthcare and oppose the misinformation and propaganda that needlessly frightens well-meaning pet owners. Veterinarians are still a trusted resource for pet owners, and we can help them make sound decisions for their pets. Though there are no simple solutions, effective communication about science is critical and can be effective at correcting misconceptions and diminishing the impact of misinformation.

For pet owners who are concerned about the safety and effectiveness of vaccines for dogs and cats, here are some resources with reliable, science-based information to help you. You also deserve an open, honest conversation with your vet based on scientific evidence, and I encourage everyone to ask their pets’ healthcare providers to address your concerns and helpo you choose the best care for your pets.

SkeptVet Vaccine Resources

AAHA Vaccination Guidelines for Dogs

AAFP/AAHA Vaccination Guidelines for Cats

WSAVA Vaccination Guidelines

Veterinary Partner: Vaccination Information for Dog & Cat Owners

Posted in Science-Based Veterinary Medicine, Vaccines | 6 Comments

Dr. Karen Becker Pleads for Freedom from Criticism

One of the least reliable sources of veterinary information the internet, Dr. Karen Becker, is at it again. 

In a recent FB post, she implies that my criticism of her anti-science claims, her promotion of unscientific, unproven, and ineffective therapies, and her spreading myths about mainstream, science-based veterinary medicine, are “attacks” equivalent to the activity of “hate groups.” Along with this comment, she reposts the absurd video produced by Rodney Habib suggesting that my work promoting science-based pet health is contributing to the problem of suicide in the veterinary profession.

There is tremendous (unrecognized) irony in this comment. Proponents of alternative therapies base much of their argument on the idea that conventional, scientific medicine is unsafe or ineffective, and this is a standard approach for Dr. Becker (e.g. 1, 2, 3). Claiming that vaccines and drugs are harmful and that scientific medicine treats only symptoms and ignores the “root”real” causes of disease is commonplace. And while she doesn’t usually go as far as her sponsor Joseph Mercola, perhaps the most prominent and aggressive anti-science disinformation providers on the planet, her long association with him shows how comfortable she is with these sorts of attacks on mainstreams science and medicine, and those of us who provide it.

Her plea for “inclusion, acceptance, or tolerance” is simply a way of saying that when she makes claims like these, or tells pet owners to use useless therapies like homeopathy or unproven, potentially harmful treatment such as Chinese herbal remedies, the rest of the profession should let her do so freely, without criticism or challenge. Want she wants is the freedom to say and do what she believes in, whether it is actually true or really helps pets or not, and not be criticized for it. Her attacks on scientific medicine are, apparently, fair play, but pushing back against her claims with logic and evidence are being mean. This is a typical double standard employed by the CAVM community (e.g. 1, 2)

Refraining from warning pet owners about the unproven and potentially dangerous nature of Dr. Becker’s approach is not being “nice” or inclusive. This is simply ignoring misinformation even when it does harm. I believe people should be treated kindly, but ideas deserve no respect other than what they earn through their logical foundations and supporting evidence.

I will say of Dr. Becker, as I say of most of the proponents of pseudoscience and anti-science misinformation, that I have little doubt she is sincere and has the best interests of her patients at heart. I also believe she is very often wrong, and her approach is dangerous and misguided. As I too have the best interests of veterinary patients at heart, I have just as much responsibility to push back against her claims as she feels she has to challenge the practices of scientific medicine. Neither of us is obliged to ignore what we see as false or dangerous claims and practices, and the standards of civility, just like the standards of evidence, should be the same for both of our positions.

I can, of course, sympathize with how frustrating and demoralizing it can be to be attacked publicly. I have no doubt the personal attacks I receive, including Mr. Habib’s ridiculous video, are as numerous and at least as harsh as any Dr. Becker experiences. My chronicles of the hate mail I receive are evidence of this. I don’t see Dr. Becker expressing any sympathy or compassion for skeptics who are attacked in this way, even when it is done in her name or defense:


This article made my blood boil because Dr.Karen Becker has more balls than any of you tiny brainwashed humans coming out of vetschool… if your veterinarian is anything like this quak continue searching for another…I LEGIT HATE u whoever u are. 

I have made great efforts to focus my criticism on ideas rather than persons, and while I admit that I can understand why referring to Dr. Becker as a proponent of misinformation and anti-science nonsense might be upsetting to her, these are descriptions of her behavior supported by a great deal of evidence, not attacks on her person. That she expresses her objection to this by reposting a video that literally demonizes me through visual and audio effects and accuses me of contributing to the suicide of fellow veterinarians is pretty stark hypocrisy.

I’m sure Dr. Becker and I would agree on some things, including the tremendous challenges vets face, financially and psychologically, and the real harm of personal online attacks. However, these serious issues should not be used as an excuse to claim an exemption from criticism, or as a distraction from the equally real danger of misinformation and anti-science ideas to veterinary and human patients.

Posted in Miscellaneous CAVM | 27 Comments

Evidence Update: Seresto Flea & Tick Collars

A couple of years ago, I wrote about the wave of concern over the safety of Seresto flea and tick collars, prompted by a sloppy bit of fear-mongering journalism. My conclusion at the time was:

There are undoubtedly some risks to this product, and it is possible that they are greater than has so far appeared in the scientific literature. The research done on this product has mostly come from companies and investigators with a financial interest in it, and that always raises some concern about the potential for bias in the data. On the other hand, such concern doesn’t somehow make collections of unsubstantiated anecdotes a reliable source of data…. Unfortunately, rigorous scientific investigation takes time; a lot more time and work that sensationalist medial reporting. My hope is that reasonable people will respond to this latest example of poor-quality reporting in a reasonable way. We likely should take a careful, objective look at the safety data for this product, and perhaps conduct further research if warranted. 

The EPA responded to the concerns raised about this product by requiring more extensive monitoring of reported problems and then analyzing the relevant evidence. This included controlled scientific research already available as well as the flood of reports from owners that always comes when the media raises the alarm about a pet healthcare product. 

As I discussed in my previous post, simply having a bunch of such reports doesn’t tell us if a product is actually safe or not. The number of reported problems has as much or more to do with public awareness and anxiety about a product as about its actual biological effects. The EPA attempted to control for this by comparing reports regarding Seresto to those for other similar products and for alternatives, such as spot-on flea control products. The agency has produced a report which, in true government agency fashion, is a compromise unlikely to satisfy anyone but easily claimed as vindication by both camps.

The bottom line is that the EPA found mild adverse events consistent with those reported in controlled studies were most common- itching and hair loss. A small proportion of dogs (about 10%) were reported to get lethargic with use of the product. More serious events were rare and could not be clearly linked to the ingredients in the product, which previous research has shown to be generally quite safe. 

The rate of these kinds of adverse effects was not significantly different from those reported for other similar collars. For mild events, there was also no difference between Seresto and spot-on products, but there were more repost of “moderate” events with Seresto than with the spot-ons.

It was generally impossible to show that any of the uncommon serious adverse events were actually caused by the collar, and many of these cases had other factors that could just as easily have been the cause, such as existing illness or other medications. The agency could not show a high level of confidence that Seresto was responsible for any of the serious adverse events with one exception- 4 dogs and 9 cats died as a likely result of being strangled by the collars when they failed to release appropriately under tension.

The manufacturer claims the report supports the safety of the product. This is largely true, but being unable to determine if many of the negative events reported were or were not related to the collar due to lack of adequate information isn’t a ringing endorsement. Information suggesting the ingredients are probably safe already existed, but this report doesn’t add much confidence to that conclusion. 

Critics of the collar also claim victory, even though the agency didn’t revoke the product approval as they wanted. They base this not on the finding of actual evidence of harm, because there wasn’t any, but on the actions the agency took in response to the review. These actions were reasonable but largely aimed at getting additional information and making the agency look like it is taking the public concerns seriously even though the existing evidence isn’t particularly strong. So what did the EPA actually do?

  • The collar is approved for only 5 years, instead of the usual 15, and additional reviews will need to be done
  • The company must collect and submit additional, more detailed information about possible adverse events associated with the collar
  • The company must develop and distribute educational materials for vets and owners discussing possible safety concerns and adverse reactions to the product
  • The company must add a warning label to the product information identifying possible adverse reactions that have been reported
  • The company must study the release mechanism and report on this to the agency

At this point, the report doesn’t do a lot to change the state of evidence regarding this product. There is reason to believe the ingredients are pretty safe; there have been a lot of reported adverse events; most of these are minor and it isn’t clear that there are proportionally more than for other pest-control products; more information is needed to determine if the benefits of the product in preventing parasites and parasite-transmitted diseases outweigh the risks. 

None of this is likely to satisfy critics of the product, but the state of the evidence is evolving, as it does, and we always have to make the best decisions we can based on the evidence available now, not the perfect evidence we would like to have. As I said previously, I don’t actually prescribe this product in my area, but I also don’t discourage owners from using it, though I do discuss the concerns and uncertainties with any who express and interest or who are using it already. This is, I believe, a reasonable compromise as we, hopefully, gather more evidence to strengthen our understanding of the risks and benefits of the Seresto collar.

Posted in Law, Regulation, and Politics, Science-Based Veterinary Medicine | 8 Comments

The VetMind Podcast

Had a nice chat with the folks at the VetMind Podcast recently about veterinary medicine, aging, and life in general!

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Diarrhea Part 3- What to do…

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Diarrhea Part 2- At the vet…

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TikTok- Diarrhea Part 1- When to worry…

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Acute Diarrhea in Dogs- Resources

SkeptVet Posts
Metronidazole for Acute Diarrhea in Dogs: An Evidence-based Treatment?

Chinese Herb vs Metronidazole for Diarrhea in Dogs: An Example of the Problems with Alternative Medicine Research

Probiotic Fortiflora: Not apparently very helpful in preventing diarrhea in shelter animals

Encouraging studies on probiotics for canine diarrhea

Fecal Microbiome Testing- Anything to It?

No Good News for Veterinary ProbioticsThe efficacy of metronidazole.

Journal Articles
Candellone A, Cerquetella M, Girolami F, Badino P, Odore R. Acute Diarrhea in Dogs: Current Management and Potential Role of Dietary Polyphenols Supplementation. Antioxidants (Basel). 2020 Aug 9;9(8):725. doi: 10.3390/antiox9080725. PMID: 32784917; PMCID: PMC7465157.

Shmalberg J, Montalbano C, Morelli G, Buckley GJ. A Randomized Double Blinded Placebo-Controlled Clinical Trial of a Probiotic or Metronidazole for Acute Canine Diarrhea. Front Vet Sci. 2019 Jun 4;6:163. doi: 10.3389/fvets.2019.00163. PMID: 31275948; PMCID: PMC6593266.

Pignataro G, Di Prinzio R, Crisi PE, Belà B, Fusaro I, Trevisan C, De Acetis L, Gramenzi A. Comparison of the Therapeutic Effect of Treatment with Antibiotics or Nutraceuticals on Clinical Activity and the Fecal Microbiome of Dogs with Acute Diarrhea. Animals (Basel). 2021 May 21;11(6):1484. doi: 10.3390/ani11061484. PMID: 34063855; PMCID: PMC8223982.

Chaitman J, Ziese AL, Pilla R, Minamoto Y, Blake AB, Guard BC, Isaiah A, Lidbury JA, Steiner JM, Unterer S, Suchodolski JS. Fecal Microbial and Metabolic Profiles in Dogs With Acute Diarrhea Receiving Either Fecal Microbiota Transplantation or Oral Metronidazole. Front Vet Sci. 2020 Apr 16;7:192. doi: 10.3389/fvets.2020.00192. PMID: 32363202; PMCID: PMC7182012.

Langlois DK, Koenigshof AM, Mani R. Metronidazole treatment of acute diarrhea in dogs: A randomized double blinded placebo-controlled clinical trial. J Vet Intern Med. 2020 Jan;34(1):98-104. doi: 10.1111/jvim.15664. Epub 2019 Nov 19. PMID: 31742807; PMCID: PMC6979100.

Tong, J. O. P. (2019). In canine acute diarrhoea with no identifiable cause, does daily oral probiotic improve the clinical outcomes?. Veterinary Evidence4(4). https://doi.org/10.18849/ve.v4i4.252

Moreno AA, Parker VJ, Winston JA, Rudinsky AJ. Dietary fiber aids in the management of canine and feline gastrointestinal disease. J Am Vet Med Assoc. 2022 Oct 26;260(S3):S33-S45. doi: 10.2460/javma.22.08.0351. PMID: 36288203.

Moore, E., & Gordon-Evans, W. . (2022). Should we prescribe oral metronidazole or probiotics for acute gastroenteritis in dogs?. Veterinary Evidence7(2). https://doi.org/10.18849/ve.v7i2.393

Holden, R. and Brennan, M. (2021), Does metronidazole increase the speed of recovery in dogs with acute diarrhoea?. Veterinary Record, 188: 33-34. https://doi.org/10.1002/vetr.44

Nixon, SL,  Rose, L,  Muller, AT.  Efficacy of an orally administered anti-diarrheal probiotic paste (Pro-Kolin Advanced) in dogs with acute diarrhea: A randomized, placebo-controlled, double-blinded clinical study. J Vet Intern Med.  2019; 33: 1286– 1294. https://doi.org/10.1111/jvim.15481

Chaitman, Jennifer, and Frédéric Gaschen. “Fecal microbiota transplantation in dogs.” Veterinary Clinics: Small Animal Practice 51.1 (2021): 219-233.

Rudinsky, Adam J., et al. “Randomized controlled trial demonstrates nutritional management is superior to metronidazole for treatment of acute colitis in dogs.” Journal of the American Veterinary Medical Association 260.S3 (2022): S23-S32.

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Liquid Biopsy- An Evidence Update

I have written about the emerging liquid biopsy tests a couple of times before (here and here). These are blood tests that are intended to find signs of cancer circulating in the blood. This can be used for screening, testing individuals with no clinical symptoms or reason to expect cancer is present, or for help in diagnosing a cancer that is suspected to be there for some other reason. I have focused on the OncoK9 test because that was both the first onee I came across and because the company has been publishing some useful follow-up research on the test since it was first released. The specifics will likely be different for each type of liquid biopsy test, but the general principles are much the same.

The potential benefits of these tests are earlier detection of cancer, which is sometimes helpful in providing more effective treatment. However, for some cancers in dogs and cats we don’t have effective treatments available, and there is little actual evidence showing that earlier treatment improves outcomes for most veterinary cancer patients, so the benefit of earlier detection is difficult to assess.

There are also potential risks to these tests. Telling owners their pets have cancer when they really don’t, and reassuring them no cancer is present when it actually is, or when it could develop at any time after the test, can be harmful to owners and to their pets. Additional testing, particularly invasive tests like biopsies, can also cause harm, and this is not always balanced by a benefit to the pet. The subjects of overdiagnosis and the rational use of diagnostic and screening tests are ones I talk about often, though I’m not convinced I have yet had an impact on how vets make use of the tests we have available. 

PetDx, the company making the OncoK9 liquid biopsy test, recently published a study looking back at test results and records from hospitals using their product and providing some information about how the test performs.

O’Kell AL, Lytle KM, Cohen TA, Wong LK, Sandford E, Rafalko JM, Brandstetter G, DiMarzio LR, Phelps-Dunn A, Rosentel MC, Warren CD, McCleary-Wheeler AL, Fiaux PC, Marass F, Marshall MA, Ruiz-Perez CA, Kruglyak KM, Tynan JA, Hicks SC, Grosu DS, Chibuk J, Chorny I, Tsui DWY, Flory A. Clinical experience with next-generation sequencing-based liquid biopsy testing for cancer detection in dogs: a review of 1,500 consecutive clinical cases. J Am Vet Med Assoc. 2023 Mar 17;261(6):827-836. doi: 10.2460/javma.22.11.0526. PMID: 36965477.

The study evaluated the results of 1500 tests submitted by veterinary clinics and attempted to determine the actual diagnosis and outcome for the patients to evaluate the accuracy of the test results. The results are broadly similar to those of the company’s previous study (discussed here), which is encouraging. It is worth noting, however, that both studies were funded and conducted by company employees, so the potential for unconscious bias to influence the methods and results is worth keeping in mind. The similarities may mean the test performs consistently in different populations of dogs, or it could be a reflection of the similar methods and biases in the design and execution of the studies.

About 64% of the tests conducted were run in patients without suspicion of cancer (screening), and 26% were submitted to aid in the diagnosis of a suspected cancer. Personally, I believe screening is the riskier of the two uses for this test, so it is disappointing that the company has been so successful at marketing this as a test to be used “just in case” there is cancer in health older pets. Those are the patients for whom the risks of overdiagnosis and overtreatment are likely the highest. Of course, they are also more likely than younger dogs to have cancer, so some will benefit from this testing, but most will not have the disease, and the balance of risks and clinical benefits is far from clear.

The test performed about the same as in the previous study. Overall, the Positive Predictive Value (PPV- the proportion of dogs with a positive test that actually had cancer) was about 89% and the Negative Predictive Value (NPV- the proportion of dogs with a negative test that did not have cancer) was about 88%. These are decent numbers, but they do suggest that about 10% of dogs with a positive test don’t have cancer, which is still a fair number of owners frightened and dogs potentially subjected to unnecessary follow-up testing, or even potentially cancer treatment or euthanasia, to no purpose. Likewise, a bit over 10% of dogs with a negative test, might actually have cancer, and this result could delay needed testing and treatment.

In the most vulnerable group, healthy dogs being screened for cancer, only 4.5% had a positive result. The proportion of these who actually had cancer (the PPV) was 75%, compared with 98% of those tested to help confirm suspected cancer. This reinforces that we must be pretty cautious about how we react to a positive screening test when ¼ of those will not actually end up having cancer. As expected, the reverse is also true: the NPV of dogs screened  was 94% (most who were tested didn’t have cancer  and most testing negative didn’t have cancer) compared to an NPV of 67% for the dogs tested because of other signs of possible cancer (a fair number of these actually had cancer, and so negative tests were less consistently correct).

A relatively small number of patients in this study had failed tests or uncertain results, and most of these got a clear yes or no answer on repeating the test. This is still a source of anxiety, frustration, and delay for those patients and their owners, but no test is ever perfect.

All-in-all, I think these types of tests are reasonable to use for trying to help decide if a dog with findings suggestive of cancer which can’t be confirmed or refuted in a more definitive way. I have run the test in one dog with a heart mass that could either have been an aggressive or a slow-growing tumor (with very different paths for the owner to choose from) and which, for obvious reasons, we couldn’t biopsy. In that case, unfortunately, the test did not find evidence of cancer, but the patient declined rapidly, which suggested something more aggressive, though no definitive diagnosis could be made. 

I have become a bit more positive in my view of these tests since I first wrote about them because the studies coming out suggests they are reasonably accurate. However, there is still no clear evidence that using these tests, at least in dogs with no other reason to suspect cancer, leads to longer life or delayed illness, and that is ultimately the point of screening. I hope this company continues to evaluate the real-world impact of the use of its tests, that other makers of such tests also do so, and ultimately that independent studies unconnected with the manufacturers of these products can provide data showing how they perform and what benefits, if any, they provide. New diagnostic and screening tests can be very valuable, but like anything in medicine they have risks as well as benefits, and it can take a bit of time and effort to determine what these are and when we should, or should not use a particular test.

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TikTok- Chewing Options for Dogs

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