Placebos for Pets? A Book Review

Dr. Brennen McKenzie released his blockbuster on alternative veterinary medicine on November 1, 2019. Placebos for Pets? The Truth About Alternative Medicine in Animals is out, and I recommend it highly. I am not a veterinarian, so keep that in mind as you read my review. But 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.

Book on alternative veterinary medicine: Placebos for Pets

McKenzie is a practicing veterinarian who also has a master of science in epidemiology (in addition to a bachelor’s degree with a double major in English literature and biology and a master’s in animal behavior). He has been the president of the Evidence-Based Veterinary Medical Association and runs the popular SkeptVet blog. That’s how I came to know of his writing.

For years, I have consulted the SkepVet blog about any new trend or alternative veterinary treatment that comes around. Dr. McKenzie presents the evidence and assesses it. This book is like his blog on steroids.

He accomplishes two main objectives with the book. First, he covers a large number of alternative treatments and interventions that are practiced in veterinary medicine. He handily groups them into natural categories, and also covers the history of the interventions. The history is often…surprising. Things that seem to have a gleam of ancient tradition about them, for instance, were invented out of whole cloth by one person a hundred years ago. Others have many subcategories that contradict each other. Other interventions are plausible but have been studied so much and for so long with only mixed results that they will probably not turn out to be miracle cures. So the book serves as a terrific reference to this large and complex topic.

The second objective he accomplishes is perhaps even more important. He teaches us how better to build good critical thinking skills and start to assess these interventions ourselves.

This is a book for an educated audience, but is perfectly appropriate for the pet owner as well as the animal professional. His writing style is clear and down to earth, and he explains some very difficult concepts with grace. There are 1,070 references, which take up fully 30% of the book (in the e-book format).

What Is Alternative Medicine?

Any topical non-fiction book has to define its terms early on, and McKenzie does so. It takes a whole chapter. Defining alternative medicine is a lot harder than one might think. It’s almost a moving target, although he does not use that phrase. He analyzes the terminology, including “alternative,” “complementary,” “integrative,” “holistic,” “natural,” and more. He discusses these as ideological categories that depend on philosophies of how we know things. I can’t present his whole argument here. You’ll really need to read the book for this, and I strongly recommend you do so. But here is one of his working definitions of complementary and alternative medicine:

The category of complementary and alternative veterinary medicine, then, is not a set of beliefs about health and disease so much as an ideological construct. It links ideas and practices primarily through a stared status as outside the medical mainstream.

Placebos for Pets?—Brennen McKenzie, VMD, MSc
herbal medicines in bowls and bottles

The Case for Evidence-Based Veterinary Medicine

Early in the book, McKenzie presents rates for human life expectancy, maternal mortality, and child mortality. (I presume these data are not available for other species.) Life expectancy started a dramatic upsurge around 1900 and continued through the entire 20th century and beyond. Maternal mortality showed a dramatic downturn starting a bit earlier (when doctors started washing their hands) and also continued through the 20th century. Likewise, child mortality dropped a bit from 1850 to 1900 and substantially after that. McKenzie points out that today, even people living in the poorest countries in the world can expect to live longer than most humans in history could have dreamed of. He goes on:

And those of us in the richest nations, with the best access to the fruits of science and technology, now routinely live more than twice as long as most human beings who ever lived. This is not because we are fundamentally different from those who went before, but because we have developed ways to understand the world and use that understanding to reduce suffering and death more effectively than ever before.

Placebos for Pets?—Brennen McKenzie, VMD, MSc

It doesn’t seem like anyone should have to defend science-based medicine, especially from within a first world country that reaps its benefits, but these are the days we live in. And Dr. McKenzie explains the processes of science, its strengths, and its limitations very well. Paraphrasing Winston Churchill’s remark about democracy, he says:

As a path to knowledge, it is long and winding, but it is far more likely to get us where we want to go than any other road we’ve tried.

Placebos for Pets?—Brennen McKenzie, VMD, MSc

How He Assesses Alternative Interventions

McKenzie has a structure for how he approaches the dozens of interventions he assesses in the book. The structure is:

  • What is it?
  • Does it work?
  • Is it safe?

Much of the information under “what is it?” was completely new to me. It taught me, once again, not to assume that because something is called “traditional” or “natural” that it necessarily is, or if so, that that is a good thing.

The “does it work?” section is often extensive. If there were easy answers here, the intervention would probably be part of evidence-based medicine already. On the other hand, McKenzie is quite clear when there is enough evidence to say, “No, it doesn’t work.” An important part of many “does it work?” sections is “is it plausible?”. He discusses the likelihood that this particular intervention could work according to the science we know, including whether the ideas at the base of it violate the scientific evidence we have.

He doesn’t dismiss interventions as often as you might expect. One surprising thing to me about the book is how open Dr. McKenzie is to the possibility of new findings related to alternative therapies. This guy is fair. He’s not some glib “debunker.” And his discussions are thorough. If there is even a chance that a therapy might be beneficial, he includes that in his writeup.

“Traditional” Medicine

After reading Placebos for Pets, any leftover warm fuzzies I had for “old” or “traditional” medicine are out the door. The magic is gone.

These ancient medical traditions (the ones that actually are ancient) were created by people who

  • had no idea of the causes of most diseases and conditions; and
  • didn’t know the functions of the organs in our bodies. They often didn’t even know basic physiology.

And as I’ll mention below in the acupuncture section, lots of supposedly traditional practices aren’t even that old.

Side Effects Are Good

Right out of the starting gate, Dr. McKenzie blows the mind of anyone who is seeking effective completely but-risk free treatments for their animal. He writes the following.

…nothing that actually does anything at all is going to be completely safe. The body of a living organism is an amazingly intricate system, with every part of the system interacting with other parts in a beautiful, bewildering complexity. The idea that we could tinker with one part of such a system and have only the effect we desire without setting off any unintended consequences in other parts is naive and unrealistic.

Placebos for Pets?—Brennen McKenzie, VMD, MSc

Boom. He summarizes this sentiment as McKenzie’s law. It goes like this:

If it has no side effects, it isn’t doing anything.

Placebos for Pets?—Brennen McKenzie, VMD, MSc

The irony here is that in my opinion, this is a far more holistic statement than I’ve ever heard from those recommending alternative approaches. The word “holistic” has been co-opted by providers of alternative treatments, but it describes competently practiced evidence-based medicine very well. The idea that you can take a substance and it will affect one part of the body and only that one part (in an ideal way) is not very holistic at all.

But his statement is going to upset a lot of people. It threatens a fervent wish we have for medicine, both veterinary and human. We want something that cures the cancer, or makes the pain go away, or improves joint mobility again—all without having any other effects on the organism.

Veterinary Medicine is Under-Studied

I was not aware of how few veterinary studies exist compared to human medical studies, although I should have guessed it. It affects the profession in interesting ways. (I can see the vets rolling their eyes in response to that. Yeah, interesting…) It means that it is very common to have studies with few animals, and studies that are not replicated, and studies that are not controlled. It means that vets sometimes have to extrapolate from human studies. It also explains why it is rational and practical for veterinarians to consider alternative medicine. I hope this book is as helpful to the veterinary profession as it can be for pet owners.


With a book that covers such a wide variety of interventions in such a comprehensive way, there is just no way to do it all justice in a review. As a sample of the thinking and information in the book, I am going to cover a small part of the chapter on acupuncture.

The chapter had several surprises. First, that although needling has been done in Chinese medicine for a few centuries, it is not as old as many practitioners believe. Also, Chairman Mao Zedong created “Traditional Chinese Medicine” as an entity for political purposes in the 1950s. That is not to say that there aren’t some ancient practices, but unifying some of them (along with other more recent practices and theories) into a system is quite recent.

McKenzie says,

…Mao’s intent in creating the TCM narrative was to suggest a time-honored and coherent set of theories and treatments because that generates greater confidence in patients and doctors.

Placebos for Pets?—Brennen McKenzie, VMD, MSc

Mao himself didn’t personally believe in or take Chinese medicine.

Some alternative treatments have been entirely made up by one person. Among these types of remedies are homeopathy (Samuel Hahnemann), Bach Flower Remedies (Edward Bach), and Essiac Tea (Rene Caisse).

Back to acupuncture. Another surprise was that Dr. McKenzie himself has certification in veterinary medical acupuncture (so-called Medical Acupuncture, which is different from the Chinese variety). He disclosed that, along with his intent to treat acupuncture as every other topic in the book and assess the research. He mentions that his personal experiences are the weakest kind of evidence.

He assesses the evidence for acupuncture through several lenses and leads us through the complexities. One limitation of acupuncture research is that it is hard to create a placebo treatment because people know when they are being stuck with needles and practitioners know when they are doing so. This means most human trials are wide-open to patient and clinician bias. Several trials that used as the placebo the placement of needles at the “wrong” points found that the placebo treatment was equally effective. Does this mean that sticking needles just anywhere is beneficial, or that both sets of patients were responding entirely to placebo effects?

There is much more to the chapter than that. But McKenzie’s general conclusion (way oversimplified by me) is that while there may be evidence that there are some places it’s good to stick a needle, this doesn’t transfer credence to the whole “discipline” (or any of the many varieties of the discipline).


dog taking a pill

To show that I take reviewing seriously (and also that I read the whole book) I try to always offer criticism. But I’m coming up a little dry, here.

At first, I wished that Dr. McKenzie had offered some instructions on how consumers can assess whether a particular intervention is working. But as I read, I concluded that that is outside of the purview of the book. How to determine the results of an individual intervention is a different book. When we are looking at statistics, one success, even a well-validated one, doesn’t matter. McKenzie’s book is about how to assess treatments. And he reminds us repeatedly that personal experience is the weakest kind of evidence. So I take back that criticism.

My only other comments involve style and are not about the content of the book. Stating common myths can strengthen them, even if the argument that follows demolishes them completely. In this book, the wonderful nutrition section does have some myths as headings. So if I’m scrolling through (I bought the e-book) and come across the heading “Commercial Diets are Poison,” that’s one more reification of the concept that the author is arguing against. This is a devilishly hard issue to handle as a writer, though. Sometimes you do have to state the myth!

One more stylistic issue: the listings in the impressive table of contents in the e-book do not link to the corresponding sections. That would be such a big help in a book this size.

Bits and Pieces I Can’t Resist Including

This bears mentioning again: Things that have been studied a lot with mixed results aren’t likely to be the cure-alls people hope for. Glucosamine is a good example of this. If it had strong positive properties for joint health, we would likely know by now.

Dr. McKenzie points out that many practitioners of alternative methods use systems that are entirely contradictory. For instance, strict homeopathy instructs the practitioner never to mix homeopathic remedies with other types of treatment. But many alternative medical practitioners do this.

A common fallacy that is the basis of a lot of alternative approaches is the “more is better” fallacy. Some substances the body needs, such as vitamins, are needed in very specific amounts. When we humans learn what the functions and benefits of such substances are, we naturally think that taking more can have super effects, maybe even curing illnesses! There are few cases of that being true. Many substances that are necessary for our bodies to function well can actually cause damage in megadoses.

Our own experiences with interventions are the weakest evidence. Hate it, but it’s true.

Final Thoughts

Reading this was a landmark life experience. Not only did I learn about a lot of specific alternative veterinary practices, I believe I started thinking the way McKenzie encourages. I certainly added a few critical thinking tools to my toolbox!

The book is very readable. But don’t expect to breeze through. It is dense and packed with information! Placebos for Pets? The Truth About Alternative Medicine in Animals is published by Ockham Publishing and is available on Amazon in e-book and paperback formats. This is an unsolicited review and I bought my own copy. (The e-book is only $6.99, an amazingly low price.)

Copyright 2019 Eileen Anderson

8 thoughts on “Placebos for Pets? A Book Review

  1. Thank you so much for this!!! I have been bemoaning the fact that there is no Snopes for dogs. Since returning to the world of dogs again 2 years ago I have been overwhelmed by the amount of Woowoo and magical thinking. I had no idea that anything like this existed. I cant wait to get this book and check out the blog you mentioned. I feel joyous!!!

  2. When I sought multiple alternative treatments for my 16 1/2-year-old golden retriever, I was trying to do as much for her as I could. I think the treatments were as much for me as anything. After a certain age there wasn’t much I could do for her so at least trying some things that would have no negative effects made me feel better. And I I think they also improve her quality of life. It helped us to bond more closely and spend quality time together during her acupuncture, laser, massage and chiropractic treatments. She seemed to enjoy going out, receiving all the attention, and so much hands on Care. I would do it again for sure.

  3. How wonderful that this book has been written. I have ordered it for my kindle and also can’t wait to get into it! I hope it will help me through the minefield that is alternative medicine.

  4. Great post! Alternative medicine is always tricky but especially with pets. I can’t wait to read the book, great review!

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