Snake Oil Tumexal and Purveyor Jonathan Nyce Finally Face the Law

Over the years, I have written about many quack medical products for veterinary patients, and about many veterinarians and others who sell or use these products with impunity despite laws intended to protect pets and pet owners from ineffective or harmful snake oil. Unfortunately, these laws are weak and rarely enforced, and even when regulators take action, it doesn’t seem to deter illegal and fraudulent behavior. 

Dr. Gloria Dodd was sanctioned by the California Veterinary Medical Board and warned by the FDA, yet she continued her practices until the end of her life, and her business is still active. Dr. Andrew Jones was sanctioned by authorities and gave up his medical license, yet he thrives as an internet entrepreneur. Dr. Al Plechner had a long career providing dangerous treatment based on untested and unscientific ideas, and though at the end of his life was he being investigated by the veterinary medical board, others continue to promote his practices. The bogus supplement Renavast was banned by the FDA, yet continues to be made and sold in the U.S. under a new name.

The seemingly endless list of people and products that freely and repeatedly violate not only any reasonable scientific standard for a medical therapy but often specific laws intended to protect consumers from quack medicines, make it is easy to feel that the effort to promote science-based medicine is entirely futile. However, every once in a while, under the rarest and most extreme of circumstances, a little glimmer of hope shines through. Today, that glimmer comes from the U.S. Attorney’s Office for the Eastern District of Pennsylvania.

United States Attorney William M. McSwain announced that Jonathan Nyce, 70, of Collegeville, PA, was charged by Indictment with wire fraud and the interstate shipment of misbranded animal drugs. The charges arise from a years-long scheme to defraud pet owners of money by falsely claiming to sell canine cancer-curing drugs.

“The defendant’s alleged conduct here is shameful,” said U.S. Attorney McSwain. “As any dog owner will tell you – myself included – pets quickly become part of the family. And when they become sick, caring owners look for hope, often doing everything they can to keep their beloved pets alive and well. The defendant is charged with taking advantage of that nurturing instinct in the worst way possible by defrauding pet owners and giving them false hope that they might be able to save their dying pet. That is both cruel and illegal, and now the defendant will face the consequences.”

I wrote about Tumexal, and Mr. Nyce, back in 2014. While I chose to ignore the irrelevant salacious details of Mr. Nyce’s personal life, I pointed out that his claims about Tumexal included many of the classic warning signs of quackery, and that it was highly improbable that his claims were true or that his product was effective. A superficial evaluation of the product web site showed many reasons to reject it as snake oil out of hand, and a further investigation into the claims and Mr. Nyce’s background made it even clearer that the person and the product should not be trusted.

Despite this, the product website was active from 2013 to 2018, and tens of thousands of dollars were made selling this product to vulnerable pet owners. My satisfaction at seeing this fraud brought to an end is diminished somewhat by how long it took to accomplish and by all the similar fraud that seems to continue unimpeded by law enforcement. And I will be honest, I have concerns that ultimately Mr. Nyce will escape conviction or punishment and eventually return to selling snake oil through some exploitable weakness in the legal case against him.

According to the U.S. Attorney’s Office press release, “’American pet owners rely on the FDA to ensure their pets’ drugs are safe and effective,’ said Special Agent in Charge Mark McCormack, FDA Office of Criminal Investigations’ Metro Washington Field Office.  ‘We will continue to investigate and bring to justice those who ignore or attempt to circumvent the law.’”

I appreciate the sentiment, but I have doubts about the effectiveness of its execution.

Posted in Herbs and Supplements, Law, Regulation, and Politics | 2 Comments

Ketogenic Diets for Dogs and Cats

Nutritional therapies and dietary fads for humans often find their way into veterinary medicine. Sometimes, there is a plausible physiologic rationale or encouraging lab animal research to justify testing specific dietary interventions in dogs and cats, and such interventions may eventually demonstrate meaningful clinical benefits. Dietary interventions for renal disease and urolithiasis, for example, are supported by both pre-clinical and clinical trial data.

Unfortunately, it is common for dietary practices in humans to become popular in veterinary patients even when there is little real evidence to support them or when physiologic differences between humans and companion animals make extrapolations from human nutrition science unreliable. The popularity of grain-free dog foods, for example, is likely explained at least in part by a cultural obsession with the supposed dangers of gluten, despite a lack of evidence to support most of these fears. This now appears to have led to real harm for some dogs who have developed diet-associated cardiomyopathy on these foods.1

One of the many extreme diets for humans that is sometimes promoted as having health benefits for veterinary patient as well is the ketogenic diet. There are groups of activists and veterinarians claiming that ketogenic diets have dramatic benefits for dogs with cancer.2 There is also interest in the potential use of ketogenic diets for epileptic veterinary patients.3–5 In this article, I will briefly review the rationale and evidence for therapeutic use of ketogenic diets.

What is a ketogenic diet?

Ketosis is a physiologic state in which metabolism of carbohydrates is reduced and metabolism of fatty acids is increased, producing elevated levels of ketones, such as acetoacetate and ?-hydroxybutyrate (?OHB). Ketogenic diets are diets which induce a state of ketosis, and they are typically high in fat, low in carbohydrates, and calorie restricted. Ketosis is readily induced in humans by high-fat diets and even short periods of calorie restriction. 

Dogs metabolize ketones much more rapidly than humans. It is difficult to induce a state of ketosis with high-fat diets, and much more prolonged periods of caloric restriction are required. However, ketosis can be induced in dogs using dietary fats that are high in certain
medium-chain triglycerides (MCTs).6–8

How does it work?

There are many theories about how ketosis might have beneficial impacts of specific health problems. Ketogenic diets are obviously useful in weight loss because they are calorie restricted, but there is also some evidence that they may suppress appetite more than other kinds of low-calorie diets.9

Ketosis may be neuroprotective due to specific effects of ketones on neurons. There is some evidence that ketone bodies have direct anticonvulsant activity, and the alterations in neuronal metabolism and neurotransmitter function in ketosis may also be beneficial in some conditions. There are even hypotheses that the effect of ketosis on neurons may be mediated by changes in the gut microbiome induced by ketogenic diets. However, there is no clearly proven or widely accepted mechanism for the neuroprotective effects of ketones.10  

It has been known since the 1920s than many cancer cells rely preferentially on glycolysis for energy, which has led to speculation that ketosis may be beneficial in slowing cancer growth or metastasis.11

What is the evidence for benefits?

There have been extensive in vitro and animal model studies of ketogenic diets, predominantly intended to evaluate their utility in treating epilepsy and cancer. Such studies have, not surprisingly, shown variable results for different diets, indications, and specific animal models. Overall, however, there is reasonable evidence of this kind to suggest ketogenic diets could be useful in treatment of epilepsy, neurodegenerative disorders, and some cancers.10–12

The clinical trial literature in humans based on this preclinical work has been encouraging for some conditions, though it is rarely clear and conclusive. Systematic reviews of studies evaluating ketogenic diets as a therapy for refractory epilepsy in children do show evidence of efficacy in some patients.13–15 The most recent Cochrane review reports, “promising results for the use of [ketogenic diets] in epilepsy. However, the limited number of studies, small sample sizes and the limited studies in adults, resulted in a low to very low overall quality of evidence.”13 Unfortunately, despite some evidence of benefits in seizure control, long-term compliance with ketogenic dietary therapy is often very poor, due inconsistent efficacy and significant adverse effects.13,16

There is less evidence to support claims that ketogenic diets have meaningful benefits in human cancer patients. Though there are promising initial results in studies evaluating ketogenic diets for adjunctive treatment of malignant glioma, “because of the paucity of clinical data, the efficacy of [ketogenic diets] for improving survival and quality of life of glioma patients remains to be proven.”17 In terms of other cancers, “evidence supporting the effects of isocaloric ketogenic dietary regimes on tumor development and progression as well as reduction in side effects of cancer therapy is missing…more robust and consistent clinical evidence is necessary before [ketogenic diets] can be recommended for any single cancer diagnosis or as an adjunct therapy.”18

The evidence base is, as always, far more limited in veterinary patients. There are no published clinical studies evaluating therapeutic ketogenic diets in cats. There are a couple of studies evaluating diets high in MCTs in dogs. One study in dogs with epilepsy found that the test diet did induce higher levels of ?OHB than the control diet, however there was no difference in seizure frequency between the groups.4 In both the test and control groups, 30% of the dogs showed a >/= 50% decrease in seizure frequency, which is consistent with the results of other studies for dogs receiving placebo.4,19

In another study, there was a statistically significant difference in the seizure frequency between dogs eating an MCT-rich diet compared with a control diet, though the mean difference was 0.36 seizures per month, which may not be clinically meaningful. Other measures of seizure frequency also differed between the diets, but the effect seemed inconsistent among individuals. While 3 of 21 dogs had complete cessation of seizures and 7 of 21 had a >/= 50% reduction in seizure frequency, 6 of 21 actually had an increase in seizures on the test diet.5

One study has reported improvements in cognitive function testing for aged lab beagles on a ketogenic diet, but there are no studies evaluating impact on function or quality of life in dogs with naturally occurring cognitive dysfunction.20 There are also no published clinical trials evaluating ketogenic diets as treatments for cancer in dogs.

What are the risks?

In humans, long-term compliance with ketogenic diets is often poor due to a combination of lack of efficacy in some individuals, poor palatability, and adverse effects. Gastrointestinal symptoms, pancreatitis, nutritional deficiencies and deficiency diseases, cardiac disease, urolithiasis, and other adverse effects have been reported in humans on therapeutic ketogenic diets.13,16,18,21–24 The safety of these diets in veterinary patients is unclear due to a lack of relevant research evidence.

Bottom Line

Ketogenic diets have been shown to reduce seizures some human patients with epilepsy. There is preliminary evidence such diets may be beneficial in slowing progression of some kinds of cancer, but there are no clear or reliable clinical trial results demonstrating this. There are clear risks to ketogenic diets in humans that limit their use, and long-term compliance is very poor.

There is no compelling research evidence in dogs or cats showing a clinical benefit to ketogenic diets. Despite the dramatic anecdotal claims made by some proponents of these diets, there is currently insufficient evidence to support recommending therapeutic ketogenic diets in companion animals.


1.        Kaplan JL, Stern JA, Fascetti AJ, et al. Taurine deficiency and dilated cardiomyopathy in golden retrievers fed commercial diets. Loor JJ, ed. PLoS One. 2018;13(12):e0209112. doi:10.1371/journal.pone.0209112

2.        Nosek J. Could a Change in Diet Cure Your Dog’s Cancer? Mod Dog Mag. May 2019.

3.        Larsen JA, Owens TJ, Fascetti AJ. Nutritional management of idiopathic epilepsy in dogs. J Am Vet Med Assoc. 2014;245(5):504-508. doi:10.2460/javma.245.5.504

4.        Patterson E, Munana K, Kirk C, et al. Results of ketogenic food trial for dogs with idiopathic epilepsy. [abstract]. J Vet Intern Med. 2005;19:421.

5.        Law TH, Davies ESS, Pan Y, Zanghi B, Want E, Volk HA. A randomised trial of a medium-chain TAG diet as treatment for dogs with idiopathic epilepsy. Br J Nutr. 2015;114(9):1438-1447. doi:10.1017/S000711451500313X

6.        Weeth L. Ketogenic diets for dogs: Treend or Truth? In: VMX 2019 Veterinary Meeting and Expo. Orlando, FL; 2019.

7.        Pi-Sunyer FX. Starvation-Induced Ketosis: Reduction in Dogs Enriched with Odd-Carbon Fatty Acids. Exp Biol Med. 1974;145(3):786-789. doi:10.3181/00379727-145-37895

8.        Crandall LA. A comparison of ketosis in man and the dog. J Biol Chem. 1941;138:123-128. Accessed November 15, 2019.

9.        Castellana M, Conte E, Cignarelli A, et al. Efficacy and safety of very low calorie ketogenic diet (VLCKD) in patients with overweight and obesity: A systematic review and meta-analysis. Rev Endocr Metab Disord. November 2019. doi:10.1007/s11154-019-09514-y

10.      D’Andrea Meira I, Romão TT, Pires do Prado HJ, Krüger LT, Pires MEP, da Conceição PO. Ketogenic Diet and Epilepsy: What We Know So Far. Front Neurosci. 2019;13:5. doi:10.3389/fnins.2019.00005

11.      Weber DD, Aminazdeh-Gohari S, Kofler B. Ketogenic diet in cancer therapy. Aging (Albany NY). 2018;10(2):164-165. doi:10.18632/aging.101382

12.      Khodadadi S, Sobhani N, Mirshekar S, et al. Tumor cells growth and survival time with the ketogenic diet in animal models: A systematic review. Int J Prev Med. 2017;8(1):35. doi:10.4103/2008-7802.207035

13.      Martin-McGill KJ, Jackson CF, Bresnahan R, Levy RG, Cooper PN. Ketogenic diets for drug-resistant epilepsy. Cochrane Database Syst Rev. 2018;11:CD001903. doi:10.1002/14651858.CD001903.pub4

14.      Martin K, Jackson CF, Levy RG, Cooper PN. Ketogenic diet and other dietary treatments for epilepsy. Cochrane Database Syst Rev. 2016;2:CD001903. doi:10.1002/14651858.CD001903.pub3

15.      Araya-Quintanilla F, Celis-Rosati A, Rodriguez-Leiva C, Silva-Navarro C, Silva-Pinto Y, Toro-Jeria B. [Effectiveness of a ketogenic diet in children with refractory epilepsy: a systematic review]. Rev Neurol. 2016;62(10):439-448. Accessed November 15, 2019.

16.      Cai Q-Y, Zhou Z-J, Luo R, et al. Safety and tolerability of the ketogenic diet used for the treatment of refractory childhood epilepsy: a systematic review of published prospective studies. World J Pediatr. 2017;13(6):528-536. doi:10.1007/s12519-017-0053-2

17.      Noorlag L, De Vos FY, Kok A, et al. Treatment of malignant gliomas with ketogenic or caloric restricted diets: A systematic review of preclinical and early clinical studies. Clin Nutr. 2019;38(5):1986-1994. doi:10.1016/j.clnu.2018.10.024

18.      Erickson N, Boscheri A, Linke B, Huebner J. Systematic review: isocaloric ketogenic dietary regimes for cancer patients. Med Oncol. 2017;34(5):72. doi:10.1007/s12032-017-0930-5

19.      Munana KR, Zhang D, Patterson EE. Placebo Effect in Canine Epilepsy Trials. J Vet Intern Med. 2010;24(1):166-170. doi:10.1111/j.1939-1676.2009.0407.x

20.      Pan Y, Larson B, Araujo JA, et al. Dietary supplementation with medium-chain TAG has long-lasting cognition-enhancing effects in aged dogs. Br J Nutr. 2010;103(12):1746-1754. doi:10.1017/S0007114510000097

21.      Bergqvist AC, Schall JI, Stallings VA, Zemel BS. Progressive bone mineral content loss in children with intractable epilepsy treated with the ketogenic diet. Am J Clin Nutr. 2008;88(6):1678-1684. doi:10.3945/ajcn.2008.26099

22.      Choi JN, Song JE, Shin J Il, Kim HD, Kim MJ, Lee JS. Renal stone associated with the ketogenic diet in a 5-year old girl with intractable epilepsy. Yonsei Med J. 2010;51(3):457-459. doi:10.3349/ymj.2010.51.3.457

23.      Willmott NS, Bryan RAE. Case report: scurvy in an epileptic child on a ketogenic diet with oral complications. Eur Arch Paediatr Dent. 2008;9(3):148-152. doi:10.1007/bf03262627

24.      Bank IM, Shemie SD, Rosenblatt B, Bernard C, Mackie AS. Sudden cardiac death in association with the ketogenic diet. Pediatr Neurol. 2008;39(6):429-431. doi:10.1016/j.pediatrneurol.2008.08.013

Posted in Nutrition | 1 Comment

Cone of Shame Podcast Interview- Placebos for Pets? The Truth about Alternative Medicine for Animals

Dr. Andy Roark and I had a great conversation about my book, Placebos for Pets? The Truth about Alternative Medicine for Animals, and all sorts of related subjects, from evidence-based medicine, to caregiver placebo effects, to acupuncture. Check it out!

Posted in Presentations, Lectures, Publications & Interviews | Leave a comment

New Evidence about When to Neuter Your Dog

I have followed the literature on the risks and benefits of neutering for many years, from writing my own literature review in 2010 to critically analyzing individual research studies on the subject here. The evidence is always growing and changing, and the attitudes of pet owners and veterinarians shift over time. When I started working as a veterinarian almost 20 years ago, routine neutering of all dogs and cats at about 6 months of age was still the dominant and recommended practice. There wasn’t much specific scientific evidence for or against this timing, and the focus of most debate about it was whether or not neutering earlier was better or worse (the evidence suggests there isn’t much difference).1–3

More recently, a series of studies have looked at health outcomes in dogs neutered at or before the traditional age and later than the traditional age.4–6 The initial papers focused on only a few breeds (golden retrievers, Labrador retrievers, and German shepherds), and they had a number of other limitations that made generalizing to neutering for all dogs or cats unreliable. I’ve discussed these individual papers in detail previously. 

A reasonable interpretation of these studies would be that there are some risks of neutering in some breeds, particularly in raising the incidence of diseases those breeds are already pre-disposed to. Earlier neutering might be a factor in this, though if you look at the studies in detail, this association doesn’t hold consistently. Some risks are seen, for example, inn golden retrievers but not Labradors, or in female dogs but not males, or in dogs neutered before 6 months or after 12 months of age but not between these ages. 

All-in-all, these studies should be viewed as evidence that the relationship between breed, size, sex, neutering and various health conditions is complex and hard to predict. No simple, one-size-fits all approach is likely to be optimal for everyone, whether it is traditional neutering at 6 months of age or alternative approaches.

Unfortunately, many people have gone well beyond such reasonable interpretations and used these studies to suggest no dogs should be neutered before 1-2 years of age, or that they should not be neutered at all. Some more extreme voices have even claimed these studies show neutering causes cancer or has other dire health effects. Such excessive claims risk causing harm when pet owners avoid the benefits of neutering out of fear of unlikely risks.

The group whose research has been most influential in changing attitudes about neutering has recently published a brief summary of a much more extensive research project that will hopefully be published in full this year. This more detailed study includes an additional 32 breeds, and the findings illustrate how complex and nuanced the issue is and how unreliable broad, rigid approaches are.

According to the authors, “Considering the occurrence of joint disorders…it is evident that vulnerability to early neutering is related to body size,” with both purebred and mixed small-breed dogs not showing the increased risk with early neutering previously reported in larger breeds.7 The issue of cruciate ruptures and hip dysplasia and other orthopedic diseases that may be influenced by neutering appear only to be a significant consideration in larger breeds which are already prone to these diseases.

Similarly, previous studies have suggested neutering, especially at an early age, may be associated with greater risk of some cancers. However, this risk varies dramatically by sex and breed, with differences seen between male and female golden retrievers, between golden retrievers and Labrador retrievers, and so on. The new evidence makes this variability even clearer. The researchers report no association between early neutering and cancer in mixed-breed dogs and, “in small-breed dogs, with the exception of the Shih Tzu, there was no association between cancer incidence and spaying at any age.”7 So much for the “neutering causes cancer” claim.

In making decisions about neutering, as with any other medical intervention, the key is to balance risks and benefits in the context of the best available evidence. As the evidence changes, we have to be willing to change our positions. I once recommended routine neutering at 6 months for all dogs and cats. I now tend to suggest that there are few medical benefits to neutering male dogs who don’t exhibit certain behavior problems, and these benefits may be offset by some risks in some breeds, especially larger breeds. For female dogs, the benefits of preventing mammary cancer and uterine infections still likely outweigh the risks in most dogs, but in breeds like golden retrievers who are at risk for some cancers that seem to be more common in neutered females, neutering later may have advantages. 

None of these are rigid, universal rules, and we must always consider the unique needs and circumstances of each animal. However, broad claims that we should never neuter or should always wait until some specific age are no more reasonable than broad claims that we should always neuter everybody at 6 months old, and our pets and patients will be better off if we move away from such simplistic thinking and consider the scientific evidence in all its complexity.


1.        Howe LM. Short-term results and complications of prepubertal gonadectomy in cats and dogs. J Am Vet Med Assoc. 1997;211(1):57-62. Accessed January 3, 2019.

2.        Olson PN, Kustritz M V, Johnston SD. Early-age neutering of dogs and cats in the United States (a review). J Reprod Fertil Suppl. 2001;57:223-232. Accessed January 5, 2020.

3.        Stubbs WP, Bloomberg MS, Scruggs SL, Shille VM, Lane TJ. Effects of prepubertal gonadectomy on physical and behavioral development in cats. J Am Vet Med Assoc. 1996;209(11):1864-1871.

4.        Torres de la Riva G, Hart BL, Farver TB, et al. Neutering Dogs: Effects on Joint Disorders and Cancers in Golden Retrievers. Williams BO, ed. PLoS One. 2013;8(2):e55937. doi:10.1371/journal.pone.0055937

5.        Hart BL, Hart LA, Thigpen AP, Willits NH. Long-term health effects of neutering dogs: comparison of Labrador Retrievers with Golden Retrievers. Coulombe RA, ed. PLoS One. 2014;9(7):e102241. doi:10.1371/journal.pone.0102241

6.        Hart BL, Hart LA, Thigpen AP, Willits NH. Neutering of German Shepherd Dogs: associated joint disorders, cancers and urinary incontinence. Vet Med Sci. 2016;2(3):191-199. doi:10.1002/vms3.34

7.        Hart B, Hart L, Thigpen A, Willits N. Best age for spay and neuter: A new paradigm. Clin Theriogenology. 2019;3(11):235-237.

Posted in Science-Based Veterinary Medicine | 25 Comments

Reviews of Placebos for Pets? The Truth about Alternative Medicine for Animals

People have been writing some great reviews of Placebos for Pets, so I thought I’d share a few. If you liked it, please take a minute to add a review on Amazon or Goodreads and help spread the word. Thanks!

“I highly recommend this book. It’s well worth reading even if you don’t have a pet. It is well-written and easy to read… It’s a useful compendium of information on alternative medicine for animals, and it teaches readers how to figure out for themselves whether they can believe a new health claim. Since I know animals can’t read or speak for themselves, I will speak out for them: thank you, Brennen McKenzie, for this book, and for all your hard work and clear thinking!”
Harriet Hall, MD
Science-based Medicine Blog

“This is a great book for all pet owners, pet professionals, and others interested in animals who need help sifting through all the information on alternative veterinary medicine…His writing style is clear and down to earth, and he explains some very difficult concepts with grace… Reading this was a landmark life experience. Not only did I learn about a lot of specific alternative veterinary practices…I certainly added a few critical thinking tools to my toolbox!”
Eileen Anderson
Author, Remember Me?: Loving and Caring for a Dog with Canine Cognitive Dysfunction

“Just finished my copy this morning and couldn’t wait to post a review! This book is simply a must-read for veterinarians, veterinary team members, and pet owners of all shapes and sizes!

Beyond simply dismissing alternative medicine for animals, Dr. McKenzie provides a wealth of details and references in each chapter. From homeopathy to cold lasers to dietary supplements, his approach of “What is It?”, “Does It Work?” and “Is It Safe?” provides the reader with an easy to understand methodology of assessing the wide range of alternative veterinary medicine practices.

As someone who spends a great deal of time helping to educate and develop veterinary staff, this book will be an invaluable resource in helping me teach our teams about scientific method and sound reasoning.”
TFD, reader review

“A clear-eyed look at how science, which underpins veterinary medicine, can either be the logical basis for how it is practiced, or sometimes be the antithesis of certain veterinary practices. There’s irony in the book’s message, not least of which being why some veterinarians may so willingly suspend disbelief in adopting some of these techniques. We ought to inherently grasp that there really is no such thing as alternative medicine, only that medicine which works, and which has a basis in science, and that which some wish would work, but either doesn’t or is as yet unproven. What we offer to the public for compensation ought to be strictly from among the former. Placebos for Pets makes this all clear. Nicely written and referenced.”
Arnold Goldman, DVM, MPH

“This is a fabulous book. The author explains in laymans terms exactly what the issues are and a very easy to understand explanation of the scientific facts surrounding the more ‘popular’ placebos. I think that this book would be just as useful to help you explain to your pseudoscientific friends and relatives exactly what it is that they’re buying.”
Mike Fairburn, reader review

Posted in Presentations, Lectures, Publications & Interviews | 1 Comment

From SkeptVet TV- Pot for Pets?

My latest video from SkeptVet TV briefly reviews the evidence for cannabis-based health products for pets. You can find more detail here:

SkeptVet Blog posts on cannabis

Veterinary Practice News columns on cannabis (1, 2)

Posted in SkeptVet TV | 1 Comment

Evidence Update- Do PEMF Devices like the Assisi Loop Work?

Since the discovery of electricity and magnetism, these mysterious forces have been thought to have healing powers. Many fanciful electrical devices were promoted in the nineteenth and early twentieth century as cures for diverse ailments or general health tonics.1 More serious scientific research into the effects of electromagnetic fields on tissues and animals began in the 1930s, and by the 1980s there was sufficient evidence for some kinds of pulsed electromagnetic filed (PEMF) devices to be approved by the FDA for use in human patients.2

Since then, a large number of PEMF devices have been marketed for both human and veterinary medical use. The scientific evidence behind these devices, from in vitro and animal model studies to clinical trials, is complex and inconsistent. Pubmed lists about 50 systematic reviews covering nearly 200 clinical trials, and there well over 1,000 articles if one includes preclinical laboratory studies. PEMF devices use a variety of designs and treatment protocols for a wide range of medical conditions, so any generalizations about the efficacy of these devices are necessarily tenuous. However, because PEMF devices are aggressively marketed to veterinarians and animal owners, some assessment of the evidence behind them is necessary.

It’s been ten years since my first review of this subject, and there was little evidence to support claims for veterinary PEMF devices at the time. Though this is still the case, some new evidence is available.

Pre-clinical Evidence
There is a large scientific literature showing that electromagnetic fields have interesting and potentially significant biological effects on animal cells and tissues. PEMF devices can affect the levels of calcium and nitric oxide in tissues, which can influence extensive and complex pathways involved in metabolism, inflammation, pain transduction, tissue growth and repair, and many other biological activities. PEMF devices have also been shown to affect gene expression, vasomotor tone, and many other physiologic processes.2–5 These studies show the potential for clinically relevant benefits from PEMF treatment. 

Lab animal studies also show effects of PEMF treatment that may be useful to clinical patients, though there is great variation in the treatment used and the results. Some evidence suggests benefits in soft-tissue and bone healing, though not all of the research is positive.2,6–8

However, it is important to understand that such in vitro and animal model findings are not sufficient to justify clinical use. Many therapies, from pharmaceuticals to manual therapies to other high-tech treatments such as low-level laser, have demonstrable effects on tissues that often do not translate into meaningful clinical benefits for patients. Clinical trials are always necessary before making confident claims for any medical therapy.

Human Clinical Trial Evidence
Though there are hundreds of clinical studies in humans for PEMF in various indications, the results are mixed and difficult to interpret. For example, there are some studies showing meaningful improvements in post-operative pain in human patients undergoing breast augmentation surgery.9,10 However, systematic reviews of studies evaluating PEMF for pain associated with osteoarthritis of the knee are mixed, with some showing no effect,11 some inconclusive,12–15 and others suggesting some benefit.16 Strong generalizations about the efficacy of PEMF for pain aren’t justified based on a literature incorporating varied treatment protocols for different indications with mixed results.

The same inconsistency exists in studies of bone healing17–20 and other clinical uses in humans.21–23 There is evidence of benefits, but it is inconsistent, and the strength of this evidence is limited by heterogeneity in treatment protocols and indications as well as by methodological weaknesses in clinical trials. 

As always, clinical trial evidence for specific indications in veterinary patients is the most relevant type of evidence for veterinarians choosing which treatments to adopt. The clinical trial literature for PEMF is currently very sparse, but there are some studies we can evaluate.

Veterinary Clinical Trials
Though some encouraging case studies and uncontrolled studies have been published,24 there have been only a few controlled clinical trials of PEMF treatment in veterinary patients. 

A small pilot study randomly divided 16 dogs undergoing ovariohysterectomy into four groups- IV saline, IV saline and PEMF, IV morphine, and IV morphine and PEMF. For 6 hours after extubation, a variety of physiologic variables were measured, including heart and respiratory rates and blood pressure, and a validated pain scale was employed by a blinded observer. There were a couple of statistical differences in blood pressure at some time points, but no identifiable analgesic effect of PEMF. The small number of animals in each group likely made the study underpowered to detect all but the most dramatic effects.25

A 2018 study evaluated the use of a PEMF device in 16 dogs undergoing hemilaminectomy for naturally-occurring intervertebral disk disease (IVDD).26 Eight dogs were randomized to active or sham PEMF treatment and evaluated in terms of a primary outcome (gait) and numerous secondary outcomes involving neurologic status, function, and pain. There was no benefit detected in the primary outcome or in the majority of secondary outcomes. 

Placing responses and one measure of pain at the surgical site did appear improved in the PEMF group compared to the control. However, when multiple secondary outcomes are evaluated in a clinical study, it is common for some differences to appear by chance despite statistical efforts to control for this,27 and the authors state that these findings “should be interpreted with caution.”26

The most recent veterinary clinical trial also used IVDD patients as subjects.28 Fifty-three patients were randomly assigned to active or sham PEMF treatment and evaluated in the hospital and by owners at home for up to 6 weeks after surgery. There were no apparent benefits in terms of pain or function as assessed by owners or clinicians, though post-hoc power calculations indicated the study was not sufficiently powered to detect some of these differences. There were some small differences in long-term appearance of surgical wounds, though all wounds healed appropriately. Owners also gave slightly more pain medication to dogs in the control group than the PEMF group, though pain was not rated differently between the groups.

Bottom Line
Despite the fact that there has been interest in the potential medical applications of electricity for over 150 years, and serious scientific research investigating PEMF has been going on for over 50 years, there is surprisingly little robust evidence showing meaningful clinical benefits. We know a lot about the physiologic effects of PEMF, and preclinical research suggests a number of clinical applications. There is clinical trial evidence from humans showing potential benefits for bone and soft-tissue healing, pain reduction, and other uses, but this evidence is inconsistent and complicated by the use of many different devices and treatment protocols. PEMF devices are widely used, and this creates the impression that they have been solidly validated, but the reality is more ambiguous. 

There is also preclinical research in veterinary species showing physiological effects from PEMF devices and potential clinical applications. However, there are very few clinical trials of PEMF in actual patients. The studies that have been published have not found consistent and convincing evidence of clinically meaningful benefits. Many outcome measures have shown no effect of PEMF, though a few have shown effects that might be meaningful. If additional independent trials confirm such potential benefits, it may be possible to have confidence in some clinical uses of PEMF. For now, however, the marketing claims of PEMF manufacturers and the excitement of proponents far exceed the strength of the available scientific evidence.

It is also worth noting that most studies of PEMF devices in human and veterinary patients have found few, if any, adverse effects. While this is reassuring, it also calls into question the real potency of these devices. Medical treatments with important and dramatic benefits that have no meaningful side effects and extremely rare, and it is more common to find that the absence of adverse effects indicates the absence of any meaningful clinical effects at all.


1.        Kang L, Pedersen N. Quackery: A Brief History of the Worst Ways to Cure Everything. New York, NY: Workman Publishing, Inc.; 2017.

2.        Gaynor JS, Hagberg S, Gurfein BT. Veterinary applications of pulsed electromagnetic field therapy. Res Vet Sci. 2018;119:1-8. doi:10.1016/j.rvsc.2018.05.005

3.        Fini M, Giavaresi G, Carpi A, Nicolini A, Setti S, Giardino R. Effects of pulsed electromagnetic fields on articular hyaline cartilage: review of experimental and clinical studies. Biomed Pharmacother. 2005;59(7):388-394. doi:10.1016/j.biopha.2005.02.002

4.        Yuan J, Xin F, Jiang W. Underlying Signaling Pathways and Therapeutic Applications of Pulsed Electromagnetic Fields in Bone Repair. Cell Physiol Biochem. 2018;46(4):1581-1594. doi:10.1159/000489206

5.        Pilla AA. Nonthermal electromagnetic fields: From first messenger to therapeutic applications. Electromagn Biol Med. 2013;32(2):123-136. doi:10.3109/15368378.2013.776335

6.        Kwan R, Lu S, Choi H, Kloth L, Cheing G. Efficacy of Biophysical Energies on Healing of Diabetic Skin Wounds in Cell Studies and Animal Experimental Models: A Systematic Review. Int J Mol Sci. 2019;20(2):368. doi:10.3390/ijms20020368

7.        Crowe MJ, Sun Z-P, Battocletti JH, Macias MY, Pintar FA, Maiman DJ. Exposure to pulsed magnetic fields enhances motor recovery in cats after spinal cord injury. Spine (Phila Pa 1976). 2003;28(24):2660-2666. doi:10.1097/01.BRS.0000099385.46102.0D

8.        Inoue N, Ohnishi I, Chen D, Deitz LW, Schwardt JD, Chao EYS. Effect of pulsed electromagnetic fields (PEMF) on late-phase osteotomy gap healing in a canine tibial model. J Orthop Res. 2002;20(5):1106-1114. doi:10.1016/S0736-0266(02)00031-1

9.        Rawe IM, Lowenstein A, Barcelo CR, Genecov DG. Control of Postoperative Pain with a Wearable Continuously Operating Pulsed Radiofrequency Energy Device: A Preliminary Study. Aesthetic Plast Surg. 2012;36(2):458-463. doi:10.1007/s00266-011-9828-3

10.      Ae H, Pilla AA. Effects of Pulsed Electromagnetic Fields on Postoperative Pain: A Double-Blind Randomized Pilot Study in Breast Augmentation Patients. doi:10.1007/s00266-008-9169-z

11.      Cao L-Y, Jiang M-J, Yang S-P, Zhao L, Wang J-M. [Pulsed electromagnetic field therapy for the treatment of knee osteoarthritis: a systematic review]. Zhongguo Gu Shang. 2012;25(5):384-388. Accessed October 18, 2019.

12.      Chen L, Duan X, Xing F, et al. Effects of pulsed electromagnetic field therapy on pain, stiffness and physical function in patients with knee osteoarthritis: a systematic review and meta-analysis of randomized controlled trials. J Rehabil Med. October 2019:0. doi:10.2340/16501977-2613

13.      Ryang We S, Koog YH, Jeong K-I, Wi H. Effects of pulsed electromagnetic field on knee osteoarthritis: a systematic review. Rheumatology. 2013;52(5):815-824. doi:10.1093/rheumatology/kes063

14.      Hulme JM, Welch V, de Bie R, Judd M, Tugwell P, Tugwell P. Electromagnetic fields for the treatment of osteoarthritis. In: Hulme JM, ed. Cochrane Database of Systematic Reviews. Chichester, UK: John Wiley & Sons, Ltd; 2002:CD003523. doi:10.1002/14651858.CD003523

15.      Negm A, Lorbergs A, MacIntyre NJ. Efficacy of low frequency pulsed subsensory threshold electrical stimulation vs placebo on pain and physical function in people with knee osteoarthritis: systematic review with meta-analysis. Osteoarthr Cartil. 2013;21(9):1281-1289. doi:10.1016/j.joca.2013.06.015

16.      Bjordal JM, Johnson MI, Lopes-Martins RA, Bogen B, Chow R, Ljunggren AE. Short-term efficacy of physical interventions in osteoarthritic knee pain. A systematic review and meta-analysis of randomised placebo-controlled trials. BMC Musculoskelet Disord. 2007;8(1):51. doi:10.1186/1471-2474-8-51

17.      Griffin XL, Costa ML, Parsons N, Smith N. Electromagnetic field stimulation for treating delayed union or non-union of long bone fractures in adults. Cochrane Database Syst Rev. April 2011. doi:10.1002/14651858.CD008471.pub2

18.      Al-Jabri T, Tan JYQ, Tong GY, et al. The role of electrical stimulation in the management of avascular necrosis of the femoral head in adults: a systematic review. BMC Musculoskelet Disord. 2017;18(1):319. doi:10.1186/s12891-017-1663-5

19.      Walker NA, Denegar CR, Preische J. Low-intensity pulsed ultrasound and pulsed electromagnetic field in the treatment of tibial fractures: a systematic review. J Athl Train. 42(4):530-535. Accessed October 18, 2019.

20.      Hannemann PFW, Mommers EHH, Schots JPM, Brink PRG, Poeze M. The effects of low-intensity pulsed ultrasound and pulsed electromagnetic fields bone growth stimulation in acute fractures: a systematic review and meta-analysis of randomized controlled trials. Arch Orthop Trauma Surg. 2014;134(8):1093-1106. doi:10.1007/s00402-014-2014-8

21.      Page MJ, Green S, Kramer S, Johnston R V, McBain B, Buchbinder R. Electrotherapy modalities for adhesive capsulitis (frozen shoulder). Cochrane Database Syst Rev. 2014;(10):CD011324. doi:10.1002/14651858.CD011324

22.      Page MJ, Green S, Mrocki MA, et al. Electrotherapy modalities for rotator cuff disease. Cochrane Database Syst Rev. 2016;(6):CD012225. doi:10.1002/14651858.CD012225

23.      Hug K, Röösli M. Therapeutic effects of whole-body devices applying pulsed electromagnetic fields (PEMF): A systematic literature review. Bioelectromagnetics. 2012;33(2):95-105. doi:10.1002/bem.20703

24.      Gaynor JS, Hagberg S, Gurfein BT. Veterinary applications of pulsed electromagnetic field therapy. Res Vet Sci. 2018;119:1-8. doi:10.1016/j.rvsc.2018.05.005

25.      Shafford HL, Hellyer PW, Crump KT, Wagner AE, Mama KR, Gaynor JS. Use of a pulsed electromagnetic field for treatment of post–operative pain in dogs: a pilot study. Vet Anaesth Analg. 2002;29(1):43-48. doi:10.1046/j.1467-2987.2001.00072.x

26.      Zidan N, Fenn J, Griffith E, et al. The Effect of Electromagnetic Fields on Post-Operative Pain and Locomotor Recovery in Dogs with Acute, Severe Thoracolumbar Intervertebral Disc Extrusion: A Randomized Placebo-Controlled, Prospective Clinical Trial. J Neurotrauma. 2018;35(15):1726-1736. doi:10.1089/neu.2017.5485

27.      Heneghan C, Goldacre B, Mahtani KR. Why clinical trial outcomes fail to translate into benefits for patients. Trials. 2017;18(1):122. doi:10.1186/s13063-017-1870-2

28.      Alvarez LX, McCue J, Lam NK, Askin G, Fox PR. Effect of Targeted Pulsed Electromagnetic Field Therapy on Canine Postoperative Hemilaminectomy: A Double-Blind, Randomized, Placebo-Controlled Clinical Trial. J Am Anim Hosp Assoc. 2019;55(2):83-91. doi:10.5326/JAAHA-MS-6798

Posted in Science-Based Veterinary Medicine | Leave a comment

From SkeptVet TV- Raw Diets for Pets

Here is my latest video from SkeptVet TV, reviewing briefly the subject of raw diets for dogs and cats. You can find more information here on the blog, or in my book, Placebos for Pets? The Truth About Alternative Medicine for Animals.

Posted in SkeptVet TV | 6 Comments

Veterinary Homeopathy: Why Are We Still Talking about This?

In two years of writing my Veterinary Practice News column about evidence-based medicine, I have largely managed to avoid the subject of homeopathy. It is the classic example of a medical practice developed before a scientific understanding of the basic mechanisms of health and disease existed, and it has remained true to 18th-century principles despite all of the subsequent advances in medical knowledge. Controversial from its beginnings,1 homeopathy has long been employed by only a few healthcare professionals, and surveys show only a tiny minority of citizens in most developed countries have used homeopathic treatment.2–4

It would seem safe, then, to dismiss and ignore this relic of pre-scientific medicine. However, homeopathy has managed to retain a small following in both human and veterinary medicine, and its proponents are sometimes visible and influential out of proportion to their numbers. Clients often ask me about using homeopathic remedies they have heard about from friends or online, often from veterinarians who support the practice. 

What is more, misleading information about homeopathy continues to be presented at major veterinary continuing education conferences and to appear in niche alternative veterinary medicine journals, which helps to create doubt about the scientific evidence concerning this practice. Attempts by regulators and professional organizations to discourage the use of homeopathy have had mixed results, thanks to vigorous lobbying against the scientific consensus by a vocal minority. Therefore, a brief evidence-based overview of veterinary homeopathy may still be useful to pet owners and veterinary professionals.

Basic Principles
The first rule of homeopathy is that something which causes certain symptoms in a healthy person is the best treatment for those symptoms in someone who is sick, a principle known as the Law of Similars.5 This clearly reflects a metaphorical approach to disease which, in modern medical science, has been replaced by specific pathophysiologic explanations derived from scientific research. Apart from this flaw, however, the Law of Similars has the obvious problem that if you give an ill patient something which creates symptoms of illness in normal individuals, you will often make them worse! 

Samuel Haahnemann, the inventor of homeopathy, discovered this problem through trial and error with his own patients.5,6 Instead of recognizing that his basic principle was flawed, however, he took the approach of greatly diluting his remedies, which reduced their ill effects. In the absence of the harm done by the traditional remedies used at the time, many of which were toxic to some degree, some of Hahnemann’s patients recovered after taking his diluted preparations. Since the only evidence available at the time for assessing efficacy was anecdote and subjective experience, this was interpreted as successful treatment.

This “success” led Hahnemanns to the second foundational principle of homeopathy, the principle of Potentization by Dilution and Succussion. This principle states that homeopathic medicines become more potent the less active ingredient they contain. (Succussion refers to shaking the remedies, since Hahnemann apparently also believed that the agitation his medicines received as he travelled on horseback to see his patients somehow increased their curative power.)5,6

Finally, homeopathy relies on a complex process for individualizing the use of homeopathic preparations by evaluating the physical and mental experiences of patients and comparing them with experiences reported by healthy individuals testing specific homeopathic remedies. The details of this process are too involved to summarize here, but they involve a purely subjective and anecdotal process that has not been, and probably cannot be, validated through controlled scientific research.

The Scientific Evidence
Despite the inherent implausibility of these concepts and the general incompatibility of homeopathic theory with established principles of physiology, chemistry, pharmacology, and other modern disciplines in medical science, there has been a lot of pre-clinical and clinical research on homeopathic remedies and treatments. The majority of this has been published in journals devoted exclusively to homeopathy of other alternative therapies, and there is often a lack of proper methodological controls and significant risk of bias in these publications. Numerous systematic reviews of homeopathy in human medicine have been published, and the majority show no evidence of real or clinically meaningful effects beyond that of placebos.2,7-35 When sufficient studies are conducted and published by committed advocates for any practice, bias will inevitably lead to some apparently positive results, but such results have not been replicated or validated by consistent, unbiased investigation.

The veterinary literature concerning homeopathy is, as always, sparser than that in human medicine, but the same general assessment applies. Despite some ostensibly positive findings in low-quality studies with high residual bias risk, the preponderance of the evidence shows no real or replicable effects. Even dedicated proponents of homeopathy are unable to find convincing high-quality research evidence for the practice when they apply accepted methods for evaluating the literature.36–42

Evidence-based medicine is always about a flexible and probabilistic understanding, and absolute, immutable conclusions are anathema to the core principles of this approach. However, evaluating homeopathy at every level, from biologic plausibility to pre-clinical and in vitro research to clinical trials leads to as confident a conclusion as science can ever muster, which is that the practice has no benefits.

The Future of Veterinary Homeopathy
It seems clear, given this scientific conclusion, that homeopathy can have no legitimate role in modern veterinary medicine. It is unethical to offer clients ineffective remedies, and even when the treatments themselves may do no harm they can mislead clients and discourage the use of truly effective treatments. 

A number of regulators and professional organizations have recognized this and taken action. The Federal Trade Commission and the Food and Drug Administration have recently issued statements warning the public that claims for the safety and efficacy of homeopathy are not supported by science. In the veterinary field, the Australian Veterinary Association, British Veterinary Association, and the Royal College of Veterinary Surgeons all have clear policy statements acknowledging homeopathy as ineffective and discouraging its use. Numerous specialty colleges in the U.S. and abroad have issued similar statements. The American Veterinary Medical Association, unfortunately, declined to adopt a similar policy in 2014 despite a finding from its own Council on Research that, “there is no clinical evidence to support the use of homeopathic remedies for treatment or prevention of diseases in domestic animals.”43

Political and economic considerations, as well as vehement advocacy and misleading information from proponents of homeopathy, have kept the method alive despite the clear scientific evidence against it. Hopefully, the current trend towards accepting the verdict of science will continue, and homeopathy will continue to decline and eventually disappear from veterinary journals and continuing education. Undoubtedly, some practitioners and clients will always choose anecdote and wishful thinking over evidence, but as members of a scientific medical professional, we have a responsibility to provide effective care for our patients and honest, accurate information for our clients. Meeting this core ethical responsibility leaves no place for equivocation or failing to clearly discourage the use of homeopathy.


1.        Holmes OW. Homeopathy and Its Kindred Delusions: Two Lectures Delivered before the Boston Society for the Diffusion of Useful Knowledge. Boston, MA: William D. Ticknor; 1842.

2.        Banerjee K, Mathie RT, Costelloe C, Howick J. Homeopathy for Allergic Rhinitis: A Systematic Review. J Altern Complement Med. 2017;23(6):426-444. doi:10.1089/acm.2016.0310

3.        Alexander H. Parents guilty of manslaughter over daughter’s eczema death. Sydney Morning Herald. Published June 5, 2009.

4.        Su D, Li L. Trends in the use of complementary and alternative medicine in the United States: 2002-2007. J Health Care Poor Underserved. 2011;22(1):296-310. doi:10.1353/hpu.2011.0002

5.        Kunzli J, Naude A, Pendleton P Tarcher PJ. Organon of medicin Samuel Hahnemann the first integral english translation of the definitive sixth edition of the original work on homoeopathic medicine a new translation. Translation of Organon Der Rationellen Heilkunde. Includes Index. 1. Homoeopathy 2. Title Design by Thom Dower manufactured in the United States of America first edition.; 1982. Accessed November 11, 2018.

6.        Bradford TL. The Life and Letters of Dr. Samuel Hahnemann. Philadelphia, PA: Boericke & Tafel; 1895.

7.        Barnes J, Resch KL, Ernst E. Homeopathy for postoperative ileus? A meta-analysis. J Clin Gastroenterol. 1997;25(4):628-633. Accessed November 12, 2018.

8.        Ernst E, Barnes J. Are homoeopathic remedies effective for delayed-onset muscle soreness: a systematic review of placebo-controlled trials. 1998. Accessed November 12, 2018.

9.        Ernst E, Pittler MH. Re-analysis of previous meta-analysis of clinical trials of homeopathy. J Clin Epidemiol. 2000;53(11):1188. Accessed November 12, 2018.

10.      Ernst E, Pittler MH. Efficacy of homeopathic arnica: a systematic review of placebo-controlled clinical trials. Arch Surg. 1998;133(11):1187-1190. Accessed November 12, 2018.

11.      Ernst E (Edzard). Homeopathy?: The Undiluted Facts?: Including a Comprehensive A-Z Lexicon. Cham?: Springer International Publishing?:;Imprint: Springer,; 2016.

12.      Ernst E. Homeopathy – The Undiluted Facts. Cham: Springer International Publishing; 2016. doi:10.1007/978-3-319-43592-3

13.      Fisher P, Dantas F. Homeopathic pathogenetic trials of Acidum malicum and Acidum ascorbicum. Br Homeopath J. 2001;90(3):118-125. doi:10.1038/sj/bhj/5800476

14.      Goodyear K, Lewith G, Low JL. Randomized double-blind placebo-controlled trial of homoeopathic “proving” for Belladonna C30. J R Soc Med. 1998;91(11):579-582. Accessed November 12, 2018.

15.      Hirst SJ, Hayes NA, Burridge J, Pearce FL, Foreman JC. Human basophil degranulation is not triggered by very dilute antiserum against human IgE. Nature. 1993;366(6455):525-527. doi:10.1038/366525a0

16.      Jonas WB, Linde K, Ramirez G. Homeopathy and rheumatic disease. Rheum Dis Clin North Am. 2000;26(1):117-123, x. Accessed November 12, 2018.

17.      Linde K, Clausius N, Ramirez G, et al. Are the clinical effects of homeopathy placebo effects? A meta-analysis of placebo-controlled trials. Lancet (London, England). 1997;350(9081):834-843. Accessed November 12, 2018.

18.      Becker-Witt C, Weißhuhn TER, Lüdtke R, Willich SN. Quality Assessment of Physical Research in Homeopathy. J Altern Complement Med. 2003;9(1):113-132. doi:10.1089/107555303321222991

19.      Linde K, Melchart D. Randomized controlled trials of individualized homeopathy: a state-of-the-art review. Altern Complement Ther. 1998;4(6):371-373. doi:10.1089/act.1998.4.371

20.      Linde K, Scholz M, Ramirez G, Clausius N, Melchart D, Jonas WB. Impact of study quality on outcome in placebo-controlled trials of homeopathy. J Clin Epidemiol. 1999;52(7):631-636. Accessed November 12, 2018.

21.      Long L, Ernst E. Homeopathic remedies for the treatment of osteoarthritis: a systematic review. Br Homeopath J. 2001;90(1):37-43. Accessed November 12, 2018.

22.      McCarney RW, Linde K, Lasserson TJ. Homeopathy for chronic asthma. Cochrane Database Syst Rev. 2004;(1):CD000353. doi:10.1002/14651858.CD000353.pub2

23.      Moffett JR, Arun P, Namboodiri MAA. Laboratory research in homeopathy: con. Integr Cancer Ther. 2006;5(4):333-342. doi:10.1177/1534735406294795

24.      Ovelgönne JH, Bol AW, Hop WC, van Wijk R. Mechanical agitation of very dilute antiserum against IgE has no effect on basophil staining properties. Experientia. 1992;48(5):504-508. Accessed November 12, 2018.

25.      Shang A, Huwiler-Müntener K, Nartey L, et al. Are the clinical effects of homoeopathy placebo effects? Comparative study of placebo-controlled trials of homoeopathy and allopathy. Lancet (London, England). 2005;366(9487):726-732. doi:10.1016/S0140-6736(05)67177-2

26.      Vickers AJ. Independent replication of pre-clinical research in homeopathy: a systematic review. Forsch Komplementarmed. 1999;6(6):311-320. doi:10.1159/000021286

27.      Vickers A, McCarney R, Fisher P, van Haselen R. Can homeopaths detect homeopathic medicines? A pilot study for a randomised, double-blind, placebo controlled investigation of the proving hypothesis. Br Homeopath J. 2001;90(3):126-130. doi:10.1038/sj/bhj/5800475

28.      Walach H, Köster H, Hennig T, Haag G. The effects of homeopathic belladonna 30CH in healthy volunteers — a randomized, double-blind experiment. J Psychosom Res. 2001;50(3):155-160. Accessed November 12, 2018.

29.      Cucherat M, Haugh MC, Gooch M, Boissel JP. Evidence of clinical efficacy of homeopathy. A meta-analysis of clinical trials. HMRAG. Homeopathic Medicines Research Advisory Group. Eur J Clin Pharmacol. 2000;56(1):27-33. Accessed November 12, 2018.

30.      Dantas F, Fisher P, Walach H, et al. A systematic review of the quality of homeopathic pathogenetic trials published from 1945 to 1995. Homeopathy. 2007;96(1):4-16. doi:10.1016/j.homp.2006.11.005

31.      Endler P, Thieves K, Reich C, et al. Repetitions of fundamental research models for homeopathically prepared dilutions beyond 10(-23): a bibliometric study. Homeopathy. 2010;99(1):25-36. doi:10.1016/j.homp.2009.11.008

32.      Ennis M. Basophil models of homeopathy: a sceptical view. Homeopathy. 2010;99(1):51-56. doi:10.1016/j.homp.2009.11.005

33.      Ernst E. Homeopathic prophylaxis of headaches and migraine? A systematic review. J Pain Symptom Manage. 1999;18(5):353-357. Accessed November 12, 2018.

34.      Ernst E. A systematic review of systematic reviews of homeopathy. Br J Clin Pharmacol. 2002;54(6):577-582. Accessed November 12, 2018.

35.      Ernst E. Classical homoeopathy versus conventional treatments: a systematic review. 1999. Accessed November 12, 2018.

36.      Doehring C, Sundrum A. Efficacy of homeopathy in livestock according to peer-reviewed publications from 1981 to 2014. Vet Rec. 2016;179(24):628. doi:10.1136/vr.103779

37.      Mathie RT, Clausen J. Veterinary homeopathy: Systematic review of medical conditions studied by randomised trials controlled by other than placebo. BMC Vet Res. 2015;11(1):236. doi:10.1186/s12917-015-0542-2

38.      Mathie RT. Controlled clinical studies of homeopathy. Homeopathy. 2015;104(4):328-332. doi:10.1016/j.homp.2015.05.003

39.      Mathie RT, Clausen J. Veterinary homeopathy: systematic review of medical conditions studied by randomised placebo-controlled trials. 2014;175(15). doi:10.1136/vr.101767

40.      Mathie RT, Clausen J. Veterinary homeopathy: meta-analysis of randomised placebo-controlled trials. Homeopathy. 2015;104(1):3-8. doi:10.1016/j.homp.2014.11.001

41.      McKenzie BA. The Evidence for Homeopathy- A Close Look.; 2013. Accessed September 13, 2019.

42.      McKenzie BA. White Paper: The Case Against Homeopathy.; 2013. Accessed September 13, 2019.

43.      Burns K. House of Delegates to deliberate again on homeopathy, acupuncturists. JAVMA News. Published 2013. Accessed September 13, 2019.

Posted in Homeopathy | 5 Comments

Calming Care Probiotic for Anxiety in Dogs

I first wrote about the subject of probiotics in 2009, and I have added quite a few articles on the subject since (12345,67891011). Overall, the evidence has been mixed but pretty poor for most conditions. The best evidence suggests some possible benefit for acute gastrointestinal problems such as diarrhea, but the veterinary probiotic literature is sparse and poor quality, with significant risk of bias, particularly given that almost all studies are funded by companies selling probiotic products. There is also evidence that the quality of probiotic products available for dogs and cats is poor.

The most recent product to enter this area is a bit different from others in that it is explicitly intended to treat behavioral problems, rather than the more typical gastrointestinal disease. Purina Calming Care is promoted “to help dogs maintain calm behavior. It supports dogs with anxious behaviors and helps them cope with external stressors like separation, unfamiliar visitors, novel sounds or changes in routine and location. It also helps dogs maintain positive cardiac activity during stressful events, promoting a positive emotional state.”

The idea that a probiotic might help with diarrhea of chronic GI disease is fairly intuitive, but the claim that feeding specific microorganisms can influence behavior seems a bit more farfetched. However, there turns out to be quite a bit of evidence in lab animals and humans that the ecology of the GI tract does have significant effects on the chemistry of the central nervous system, and the mood and behavior that results.1,2 There are also a number of reviews of experimental studies in humans specifically evaluating probiotics as treatments for anxiety and depression, and while there are plenty of limitations and lots of inconsistency, the evidence is actually fairly encouraging.2–7

Of course, the devil is in the details, and even in humans it is difficult to say with confidence that any given probiotic will help any specific patient. Though there is some positive clinical research, the studies use different probiotics in different forms for different populations with different problems, and this heterogeneity makes generalizations about the value of probiotics for mood disorders unreliable. In veterinary medicine, the situation is considerably worse since the evidence is far less robust.

There are no fully peer-reviewed studies of probiotics for behavioral problems in dogs or cats. The best we have is an abstract of a Purina study evaluating their Calming Care product in dogs. Twenty-four dogs described as “anxious” (no more formal diagnosis was given) were tested with and without the product over six-week periods. Purportedly blinded observations of behavior and measurements of objective markers such as heart rate and cortisol levels in saliva all showed changes during the period on the probiotic that would suggest a beneficial effect. However, the information about how the study was conducted is too limited to effectively appraise its quality, and of course it is an in-house study run by the company to provide marketing material for their own product, so potential bias is certainly a concern.

As I have pointed out previously, the risks of probiotics appear to be low, though some cases of direct injury and instances of transmission of genes for antibiotic resistance passed from probiotic organisms to pathogenic bacteria have been reported. In the face of encouraging but incomplete lab animal and human evidence and virtually no research in veterinary patients, it is not unreasonable to try a product like Calming Care for dogs with anxiety-related problems, but we can have little confidence in its effects.


1.        McKean J, Naug H, Nikbakht E, Amiet B, Colson N. Probiotics and Subclinical Psychological Symptoms in Healthy Participants: A Systematic Review and Meta-Analysis. J Altern Complement Med. 2017;23(4):249-258. doi:10.1089/acm.2016.0023

2.        Wang H, Lee I-S, Braun C, Enck P. Effect of Probiotics on Central Nervous System Functions in Animals and Humans: A Systematic Review. J Neurogastroenterol Motil. 2016;22(4):589-605. doi:10.5056/jnm16018

3.        Nikolova V, Zaidi SY, Young AH, Cleare AJ, Stone JM. Gut feeling: randomized controlled trials of probiotics for the treatment of clinical depression: Systematic review and meta-analysis. Ther Adv Psychopharmacol. 2019;9:204512531985996. doi:10.1177/2045125319859963

4.        Liu RT, Walsh RFL, Sheehan AE. Prebiotics and probiotics for depression and anxiety: A systematic review and meta-analysis of controlled clinical trials. Neurosci Biobehav Rev. 2019;102:13-23. doi:10.1016/j.neubiorev.2019.03.023

5.        Wallace CJK, Milev R. The effects of probiotics on depressive symptoms in humans: a systematic review. Ann Gen Psychiatry. 2017;16(1):14. doi:10.1186/s12991-017-0138-2

6.        Pirbaglou M, Katz J, de Souza RJ, Stearns JC, Motamed M, Ritvo P. Probiotic supplementation can positively affect anxiety and depressive symptoms: a systematic review of randomized controlled trials. Nutr Res. 2016;36(9):889-898. doi:10.1016/j.nutres.2016.06.009

7.        Huang R, Wang K, Hu J. Effect of Probiotics on Depression: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. Nutrients. 2016;8(8):483. doi:10.3390/nu8080483

Posted in Herbs and Supplements | 3 Comments