Editor’s note: With Clay Jones being unavoidably prevented from his usual slot, we instead offer a post by Brennen McKenzie for your enjoyment!

The Truth About Pet Cancer (TAPC) is a slick bit of propaganda. Although it contains some interesting, even promising ideas, these are unfortunately served with a heavy seasoning of misinformation and fear-mongering. Hypotheses and opinions are presented as established facts, and anyone who disagrees is implied to be ignorant at best, venal and corrupt at worst.

It would have been possible to make a substantive, accurate, and very interesting documentary about some of these topics, from ketogenic diets to the epidemiology of cancer in pets. The reason The Truth About Pet Cancer isn’t such a film, and isn’t especially concerned with the truth, likely has to do with the biases and agendas of the participants, which I have already discussed elsewhere. Many of these folks will be familiar to readers of SBM, and several were involved in the template for The Truth About Cancer, which Dr. Hall ably reviewed several years ago.


The participants seem to fall into several broad categories: 1) Proponents of pseudoscience and critics of science-based approaches in human health; 2) Proponents of pseudoscience and critics of science-based approaches in the veterinary field; 3) Mainstream veterinarians or researchers in legitimate scientific fields with an interest in or sympathy for “integrative medicine” or for unconventional nutritional approaches, such as ketogenic diets.

Individuals in the first two categories are clearly the architects of this bit of propaganda. Several of these are not only evangelists for alternative medicine and lifestyles but purveyors of quite astonishing and bizarre conspiracy theories.

Those in the third category mostly seem like pretty reasonable people, so their reasons for participating in this project are less clear. Some have been so blinded by their enthusiasm for a particular idea, such as ketogenic diets, that they are willing to overlook the use of their statements to promote pseudoscience and attack science and science-based medicine. Others may have been misled as to the nature of the project and how their participation will be used. Many say perfectly reasonable and science-based things in their interviews, though these comments are often interwoven with more extreme or unscientific comments to build a narrative that might not accurately reflect these views.

I have spoken to one person in this group who was actually quite angry about how their words were used and their implied support for claims they do not actually believe in. Others I have communicated with indicate that they stand by their own comments but take no position for or against the claims made by others. It is undoubtedly true that not every individual who participated agrees with every claim made by all of the other participants. It may well be that some of the more science-minded participants are not even aware of how bizarre and anti-science the views of some of the organizers and other participants are.

Regardless of how the more reasonable folks interviewed came to be associated with this project, however, their reputations are now tied to it to some degree, and it is their responsibility to disavow any aspects of the project they feel are inaccurate or untruthful or that misrepresent their views in some significant way. Failing to do this gives tacit approval and support to the project, and to the many falsehoods, errors, and attacks on science-based medicine it contains.

The argument

An exhaustive review of every claim made in this series would be impractical. Not all participants agree on every claim, and they are often too vague be assessed by a critical appraisal of the research literature. However, there are several consistent themes and hypotheses that run through the series, and it is important for the pet-owning public to know that the evidence, and the truth, is not what it is made to seem in this series. I will briefly cover the evidence concerning some of the major claims made in this series. Here is the general argument presented:

  1. Cancer is rampant in dogs and cats. More pets are getting cancer and at younger ages than ever before.
  2. The main causes for this are:
    • Commercial pet foods; and
    • Our toxic environment, including chemicals in commercial pet diets, vaccines, conventional parasite preventatives and medicines, GMOs, wifi and other emf sources, and many other bad things.
  3. Science-based veterinarians like myself are ignorant about the problem and the causes, largely because of entrenched dogma and the influence of pharmaceutical and pet food companies. At best, we are ignorant, at worst we refuse to study and accept effective strategies for preventing and treating cancer because we make our living from sick animals and from foods and drugs that contribute to the problem. Conventional methods for treating cancer in dogs and cats (pejoratively described as “cutting, burning, and poisoning”) are (depending on the person being interviewed) vary between useful but insufficient, to totally ineffective, to actually causing more harm than benefit.
  4. The TRUTH about cancer treatment is alternative therapies and diets are safer and more effective than conventional cancer therapy. These include:
    • “Detoxing” with food and alternative therapies;
    • Completely reinventing feeding practices, with an emphasis on fresh, raw, ketogenic diets and calorie restriction (feed them like the wolves they are inside); and
    • A plethora of alternative medicine treatments.

Claims and the evidence

Claim 1: Cancer is rampant in dogs and cats. More pets are getting cancer and at younger ages than ever before


You look back 50 years ago, where some will say that the cancer rate may have been 1 in 100 dogs. Today, according to PhDs, the dog has the highest rate of cancer of any mammal on the planet. Literally, from last year, them saying 1 in 2, to this year, 1 in 1.65 dogs will succumb to cancer…And 1 in 3 cats.

In my experience, we are seeing cancer in younger and younger animals.

Breast cancer rates have gone up despite every effort. Prostate cancer rates have gone up despite every effort. Virtually every cancer is more common now than it was then.

The cancer rate in pets parallels the cancer rate in humans. We’re all getting cancer.

We do see, commonly, dogs under 18 months of age with terminal cancer. What used to be a disease of the old is now unfortunately a disease of the young.

What’s scary in cancer, human cancer, from 2012 to now, 2016. The rate of increase in deaths per year is actually going up faster than new cases per year. So, this says we’re not making any progress. We’re not making any major progress in the war on cancer. It’s getting worse.

Part of evaluating this claim depends on assess what is actually being said. If the point is merely that cancer is common, that is certainly true. If the point is that cancer is more common than it used to be, then this may be true, false, or uncertain depending on which type of cancer, which species, and lots of other variables that are ignored in this series. As far as the specific numbers offered for cancer rates, these are misleading and largely meaningless, and they don’t conform to how rates of disease occurrence are usually described in epidemiology.

The claim that cancer rates are rising across the board in humans is clearly wrong. Overall cancer incidence in the United States is 439.2 cases per 100,000 people per year based on data from 2011-2015. This general figure isn’t really very useful since it leaves out all the important details, including who gets what type of cancer and what the risk factors for each are. However, since TAPC makes quantitative claims about cancer rates in humans and animals, I thought it worth providing some real data.

The latest evidence from the National Cancer Institute shows an overall decline in cancer incidence and mortality in humans, though incidence may be declining, stable, or increasing for some cancers and some populations. Dr. Gorski has previously addressed the claims that conventional, science-based medicine is “losing the war on cancer,” and he has demonstrated that, while the issue is more complex than the simplistic comments in this series allow, on balance such a claim is not true.

The risk factors for developing cancer are complex, and as these change so do the rates of different types of cancer. As fewer people smoke tobacco, for example, lung cancer rates decline.

Similarly, stomach cancer risks have declined over time as risk factors (including H. pylori infections, salt intake, smoking, and others) have declined. As new risk factors are identified and reduced, rates for associated types of cancer will likely decrease. The introduction of the Human papilloma virus (HPV) vaccine, for example, has dramatically reduced the rate of HPV infection. Since HPV is responsible for most cervical cancer, and other cancers as well, this will likely dramatically reduce the incidence of this type of cancer.

The incidence of other types of cancer, of course, are increasing. Some of this is due to better diagnosis, as when prostate cancer diagnoses increased dramatically with the introduction of the prostate specific antigen (PSA) test and then decreased as the problem of overdiagnosis was recognized and screening efforts decreased. Other cancers are truly happening more often, due to an increase in relevant risk factors (for example obesity), or simply due to the aging of the population.

Cancer rates increase with age due to the accumulation of damage to DNA, cumulative exposure to environmental risk factors, and many other complex changes in biology that occur with aging. As science and science-based medicine do a better and better job of reducing preventable deaths in younger people and extending average life expectancy, the risk of age-associated diseases, including cancer, will naturally increase. Overall, however, the evidence does not support the claim that in humans cancer is a rampant “epidemic.”

So what about pets? Is cancer increasing in dogs and cats? The answer, unfortunately, is that nobody really knows for sure. The kind of epidemiologic data collected for humans to help assess cancer incidence over time is much weaker and more scarce for companion animals. The claims made in this series, therefore, are speculation and opinion, not established facts.

There have been only a few studies attempting to assess the rates of cancer in dogs and cats over the last 50 years. These have used different methods and different populations, and they have been conducted at different times, so it is very dangerous to make direct comparisons between them. Additionally, we rarely have accurate information about the age distribution of pet populations, cancer rates vary greatly between breeds, and there is dramatic variation in how much effort is put into finding and identifying different types of cancer in dogs and cats. There are no formal, organized screening programs, many dogs and cats receive little or no medical care, and owners often choose not to pursue a specific diagnosis when their pets develop a growth or become ill. Therefore, the real rates of different cancers, and any change over time, is very difficult to know with any certainty.

The studies that have been done do show some consistent patterns that likely reflect underlying cancer biology. Age, for example, is always a significant risk factor, with more cancers seen in older animals. The claim that cancer is becoming “a disease of the young” is certainly not consistent with the evidence we have.

Some breeds have higher rates of specific cancers, and this indicates genetic risk factors are important, despite suggestions in TAPC that this is a false assumption mainstream science is mistakenly obsessed with. Other individual risk factors are important as well, such as sex and location. Females, for example, have much higher rates of mammary cancer in populations where the dogs are frequently not spayed, but this common cancer virtually disappears from populations where early neutering is the norm. Trends over time are rarely reported and are difficult to interpret due to changes in study methods, our ability to detect cancer, and the willingness of people to seek diagnosis and treatment for their animal companions.

Here is a glance at some of the few epidemiologic studies that have been done on cancer incidence in dogs and cats:

  • Dorn, 1968 – 381.2 per 100,000 dogs over 3 years, 155.8 per 100,000 cats over 3 years
  • McVean, 1978 – 507 per 100,000 dogs, 412 per 100,000 cats
  • Reid-Smith, 2000 – 852 per 100,000 dog-years, 319 per 100,000 cat-years
  • Dobson, 2002 – 747.9 per 100,000 dogs/year
  • Merlo, 2008 – 99.3 per 100,000 dog-years (males), 272.1 per 100,000 dog-years (females)
  • Vascellari, 2009 – 143 per 100,000 dogs/year, 63 per 100,000 cats/year

The variation here is significant. This reflects the different study methods, time periods, locations, and many other variables. In general, the rates in dogs are similar to the much more reliable overall numbers reported for humans, while the rates in cats appear to be consistently lower.

However, the devil is in the details. In nearly all studies, mammary cancer is the most common cancer, and as a result females have higher rates of cancer than males. However, in populations where most females are neutered, mammary cancer virtually disappears, so these numbers don’t reflect this single, clear risk factor.

There is virtually no data to assess changes in cancer incidence over time. One of these studies (Merlo, 2008) used a database with nearly 20 years of data collection to attempt to make some assessment of trends over time. Here is their summary of that data:

These data do show an overall increase in cancer incidence for males, though most of this appears to be only in the most recent time period. For females, cancer incidence has fluctuated over time, most likely due to changes in mammary cancer rates caused by more people choosing to neuter their female dogs. This single, tenuous data set does not support the dramatic claims of rampant global increases in all cancer made in this video series.

Another of the claims made in this series, that cancer is exclusively seen in companion animals because of their diet, vaccines, and other conventional healthcare is absurd and manifestly false. Belgua whales in the St. Lawrence River, for example, have a tremendous cancer burden. And Tasmanian devil populations have been decimated by a bizarre transmissible tumor (which I’m sure the folks behind the series will be disgusted to learn, is being successfully fought with a vaccine). This is just part of the Appeal to Nature Fallacy, the idea that somehow life without human activity or technology is better and healthier than. This is one of the main ideological pillars of the raw diet argument, and it is no less ridiculous applied to our pets than applied to ourselves.

Claim 2: Causes of cancer

The causes of cancer are claimed to include:

  • Commercial pet foods; and
  • Our toxic environment, including chemicals in commercial pet diets, vaccines, conventional parasite preventatives and medicines, GMOs, and many other bad things.

Though the main target of the makers of these videos are commercial pet foods and dietary carbohydrates, there are many other casual references to purported causes of the supposed “cancer epidemic” in dogs and cats. Nearly all of these are speculative and unproven, a few are clearly false, and a few may be true under specific circumstances, though even these are misrepresented and oversimplified in the videos.

Commercial pet food


Processed food is toxic. There’s some studies that indicate it’s probably carcinogenic.

When we feed processed pet food, which is so rich in sugar, particularly the ubiquitous dry food, we are feeding the perfect cancer growth diet. Our veterinarians, our oncologists, and our friends in human medicine appear to have no idea that this is the case. And isn’t that terrible? We recommend foods to our cancer patients that are going to make the cancer worse, that are going to kill the patient.

How does the pet food industry feed cancer? They feed it very well! They feed it with sugar, and cancer grows on sugar.

The overly processed, no nutrition, high sugar and starch with actually toxic properties to it. That whole package is what scares me.

Any processed food is going to be a problem with cancer as far as I’m concerned.

There is a very well-known cancer-causing agent that all veterinarians learned about in medical school. It’s called aflatoxin. It’s a toxin that’s made by mold, mold that grows on grains. ..It’s in your dog’s food….When a vet says that food has nothing to do with cancer and they’re ignoring that stuff, they need to be replaced as a vet, or they need to read the research.

Most of the food is cooked, which means there’s no activity left in it. And the fact that it’s extremely toxic. I mean, you’re basically poisoning your pet.

Tens of thousands of dogs and cats live long, healthy lives eating commercial pet food. The idea that these diets are causing an epidemic of cancer, disease, and death and that mainstream veterinary medicine either hasn’t noticed or doesn’t care is nonsense. We cannot yet predict the “optimal” diet that will minimize any and all disease risk for a given individual. It may even turn out to be true that fresh, homemade diets have health advantages, though this has not yet been tested, much less proven. However, we can be quite certain that we are not feeding horrible poisons to our pets when we give them reputable commercial foods.

Humans, dogs, and cats are all very different species with different nutritional needs. Though they share an evolutionary relationship with wild canids, dogs are not wolves, and they have multiple genetic and anatomic adaptations to living with humans and sharing our food. They do not have a nutritional requirement for dietary carbohydrates, but they are perfectly able to utilize them as a source of calories and nutrients, and there is no evidence that dietary carbohydrates contribute directly to cancer or other disease risk in dogs.

There are only a few studies looking at diet and cancer risk in dogs and cats. Most of these rely owner recollections for data about diet, which has proven a very unreliable approach in people. There are no studies at all showing restricting dietary carbohydrates reduces the risk of developing cancer in dogs and cats.

One study from nearly 20 years ago is often cited to suggest low-carb diets are beneficial for dogs with lymphoma, a type of white blood cell cancer. However, the truth is that the study was really looking at something else (fish oil and arginine supplementation), not carbohydrates. Both the test and control subjects in this study ate the same amount of carbohydrates, and there was no apparent impact of the low-carb diet on their cancer.

Despite the constant drumbeat in this series that carbohydrates are synonymous with “sugar” (which they are not), and are toxic and carcinogenic, this claim is pure speculation. There are lab animal studies and epidemiologic research in humans which suggest possible relationships between carbs in the diet and cancer. There are interesting features of the metabolism of cancer cells that suggest diet might have some influence on cancer progression and response to treatment. But there is no real-world, clinical trial evidence that supports the claim that dietary carbohydrates cause cancer in pets or that lower carbs will prevent or help treat cancer.

There are many other unproven or clearly false claims made about commercial pet diets. I’ve debunked some of these over the years elsewhere. These are standard talking points for advocates of pseudoscience and alternative nutritional approaches, but they range from unproven hypotheses to outright nonsense, and none can fairly be described as proven facts.

“Processed” pet foods

I think it is also important to address the concept of “processed” food, since this term is egregiously misused in TAPC. Obviously, anything not eaten raw and unwashed is “processed” to some extent, the term is broad enough to be nearly meaningless. And despite the negative implications usually attached to the phrase, some kinds of processing clearly improve the safety and nutritional value of foods (washing and cooking, in particular). However, in TAPC, the term is used in an exclusively negative way, as a synonym for “unhealthy” and “toxic.”

Most people probably hear the term and think of snacks and convenience foods for humans – potato chips, packaged hot dogs, frozen chicken nuggets, and so on. And there is some limited evidence that such foods may increase cancer risk in humans. Whether this is simply an association (e.g. people eating such foods are more likely to be overweight, exercise less, and have other risk factors for cancer), or a causal relationship (something in these foods increase cancer risk, directly or indirectly through something like increasing obesity) is unclear. In any case, clearly no one thinks a diet of convenience foods and snacks alone is healthy, and mainstream dietary guidelines recommend plenty of fresh fruits and vegetables, whole grains, low-fat protein sources, and so on because there is evidence to support the health benefits of such a diet. Therefore, it is reasonable to wonder how a packaged commercial diet could be safe or healthy for our pets.

One key difference between human convenience foods and pet food is that the former are designed primarily to appeal to consumers. Taste, appearance, mouth feel, packaging, price, and most other characteristics of packaged foods for humans are aimed at getting people to buy them. Nutritional considerations are a negligible factor, apart from those that can be used as marketing tools (e.g. calling a cookie full of sugar “low-fat” or slapping a meaningless label like “no GMO” or “All Natural” on something to fool people into imagining it is healthier).

Pet foods, in contrast, are typically designed by nutritional experts to be complete and balanced, and support normal health. Sure, they have to be appealing to pets in terms of taste and smell, and to owners (which includes being affordable and often leads to plenty of meaningless verbiage on packages). However, extensive research evidence exists demonstrating the nutritional needs of companion animals, and meeting these needs is a core requirement for a pet food from a reliable manufacturer. Pet foods are intended to be the primary source of nutrition, and they are formulated and manufactured with this in mind.

Now most pet foods intended for adult maintenance or for growth in puppies and kittens have not been tested in large-scale, long-term clinical studies to demonstrate their impact on health. Some feeding trials are done for many diets, but these are foods, not medicines, so they are not required to meet that level of evidence. There are only a few commercial diets specifically intended for therapeutic medical uses, such as supporting animals with kidney disease, dissolving bladder stones, and so on. These have been through extensive pre-clinical and clinical trial testing to validate medical claims made for them.

While it would be nice to have this kind of data for all commercial diets, it is false to suggest this means the health effects of feeding commercial foods haven’t been studied. And it certainly makes no sense to suggest that alternatives, such as raw or homemade diets, are healthier when there is even less evidence for the impact of those diets. The limited evidence so far suggests these alternatives are likely to be nutritionally incomplete or unbalanced (e.g. 1, 2, 3, 4) and have risks, such as exposing humans and pets to serious infectious diseases, that are not outweighed by any proven benefits (1, 2, 3).

In theory, fresh, homemade diets that are properly formulated might be healthier than commercial pet foods. This is a reasonable hypothesis that can and should be investigated. However, the folks behind TAPC are basing their claims entirely on ideology, misuse of pre-clinical science, and ignoring the evidence and expertise of real veterinary nutrition experts, who are repeatedly dismissed using the shill gambit. The fearmongering in this series about “processed” foods and commercial pet diets is not founded on real evidence and is deeply misleading to pet owners trying to make decisions about how best to feed their animal companions.


“Toxins” are one of the classic bugbears of the pseudoscience community, and they make multiple appearances in the TAPC videos. There are too many claims to critique each in detail, but here is a brief list of substances purported in this series to be causing the supposed “cancer epidemic” in pets, along with some resources explaining why these claims are, at best, unproven and implausible and, in most cases, simply false.

  • Grains in pet food

    Absolutely, grains can play a significant role on a risk of cancer…It’s a roll of the dice. Are you going to roll the dice and feed grains or not?

    There is no plausible reason to believe grains are inherently harmful or increase cancer risk. (1, 2, 3)

  • GMO ingredients

    We saw that the number one ingredient in this new formula that we had been forced to use was either soy or corn, I believe, one of the two big, bad GMO products that you never want to feed to yourself or your kittens…But we believe now that that was what killed the kittens, and we know, we know what GMOs, genetically modified organisms, we know what they do to stomachs.

    We’ve already seen that the GMO corn is causing sterility and tumors in rats.

    Decades of research have failed to find real evidence that GMO ingredients cause harm (1, 2, 3, 4, 5, 6) or that “organic” or “non-GMO” ingredients have health benefits (1, 2, 3, 4, 5, 6).

  • Colors and preservatives
    No reliable evidence has linked the presence of these ingredients in pet foods to any increased disease risk (1, 2, 3, 4, 5, 6, 7, 8, 9, 10).
  • Fungal toxins in pet foods

    There is a very well-known cancer-causing agent that all veterinari­ans learned about in medical school. It’s called aflatoxin…It’s in your dogs’ food/

    Corn and other grains are sometimes contaminated with molds which can produce substances toxic to humans and other animals. As with any toxin, the dose determines the effect. In high enough amounts, these can cause both acute and chronic illness. Fortunately, low levels of these compounds are not harmful. The FDA has guidelines for safe levels of these fungal compounds in human and animal foods. The guidelines for grains used in pet food are as strict, or stricter, than those for human consumption. There have been instances in which pet foods exceeded these levels and dogs or cats have fallen ill. However, these instances are the exception, in which food safety rules and protections have not been adhered to. There is no evidence that under normal circumstances these compounds are present at harmful levels in commercial pet foods.

  • Gluten

    Pets are not meant to break down gluten. They don’t know how to break down gluten. It’s very toxic to them.

    The gluten-phobia that has been influencing what people choose to eat is largely nonsense, and there is no good evidence that gluten-free diets are healthier for most people who do not suffer from celiac disease. The same phobia, unfortunately, has taken hold in those advocating for unconventional diets for pets, and there is even less evidence to support it. As with grains in general, there is no reliable evidence gluten has negative health effects on pets, other than a rare condition in the Irish setter.

  • Vaccines

    We try to treat cancer with chemotherapy but that actually causes cancer, right? We try to prevent disease with vaccines, but they actually cause disease, actually cause cancer.

    Considering they are very safe and probably the most effective healthcare intervention ever discovered, vaccines get blamed for nearly every disease we can’t firmly pin on another cause, and even some we can. In terms of cancer, there is no evidence that routine vaccination increases the risk of most cancers.

    The exception is a rare disease known, appropriately, as Vaccine-Associated Fibrosarcoma (VAS) in cats. This has been estimated to occur in between 1 in 5,000 and 1 in 10,000 vaccinations. VAS occurs almost entirely in association with specific vaccines (killed, adjuvanted rabies and leukemia vaccines) which have largely been replace by non-adjuvanted vaccines. They also occur more frequently in some populations than in others, suggesting genetic and other interacting risk factors. While it is perfectly correct to say, based on this, “vaccines can cause cancer,” it is not correct to claim or suggest that vaccines are a common or important risk factor for any cancer other than feline VAS.

  • Flea and tick products

    Flea and tick treatments. We are putting poisons on the back of the necks of animals, pills in their bodies that change the biochemistry of the blood. So, when a flea or tick bites you and drinks your blood it dies. That’s not gonna cause any cancer?

    There is no reliable evidence that modern flea and tick preventatives cause cancer in dogs and cats. Rodent toxicity studies are sometimes cited to show this, but these don’t appropriately represent the real world since they use difference chemicals in a different species at much higher doses.

    One case/control study in dogs from 1989 suggested an association between “topical insecticide” use and bladder cancer in a breed genetically predisposed to such cancer. Those who use this to support claims that flea control products cause cancer ignore a lot of important facts. For one, the study did not show causation, only association, and this has not been shown in other breeds not at increased risk for this type of cancer. This study also looked at flea and tick products which are no longer used, not at current products on the market which did not exist in 1989. Finally, there have been other studies since showing no association between this cancer in this breed and newer products and no association between flea and tick products and another type of cancer (lymphoma).

    As usual, there is even less information available on this subject for cats. One study found no overall relationship between flea and tick product use and one type of oral cancer. Various forms of these products showed inconsistent and implausible association patterns (e.g. collars raised risk but shampoos were protective), and again none of the products commonly used today were studied.

Claim 3: Ignorance, bias, and self-interest

It is standard practice for proponents of unconventional, unproven, and quack ideas to begin by claiming that any opposition to these ideas must stem from ignorance, bias, or self-interest. TAPC claims that conventional vets don’t accept Claims 1 and 2 because of ignorance, financial self-interest, or the malign influence of Big Pharma and Big Pet Food, that conventional cancer therapy isn’t very effective, and that it often does more harm than good.

We’re not taught in vet school how to identify lifestyle obstacles that we need to be helping clients remove in order to prevent cancer from occurring…So, we’re waiting until these animals get cancer and then we have to talk about cutting it out, poisoning it out with chemotherapy, or burning it out with radiation.

Linus Pauling, you know two-time Nobel Prize-winning scientist has said, “Cancer research is the most fraudulent branch of research in the world.” And just we encourage this narrow thinking, non-reproducible results….We’re stuck in this dogmatic, narrow-minded view about what cancer is and it’s just not working.

We’ve got an industry that seems to be driven by the dollar as opposed to trying to help pets. Just the same way the cancer industry with people is driven by profit motive and they don’t care about the cancer patients. It seems the vet practice is the same.

When vets go to vet school they come with open hearts. They’re trusting to be taught up-to-date, the best information, but they’re not. You know why?… Currently what students are taught in vet school are taught by the veterinary pet food companies.

[Vets] haven’t really taken the time to look at it as much as their customers. So, when—it’s like going into a doctor’s office and you know that the client knows more than the doctor.

I think that’s a reason also why it’s not really researched in universities. Most universities get sponsored by these big billion-dollar companies, and you don’t really want to step on their toes, I guess.

Our dying prematurely and suffering is sustaining a huge medical industry to be profitable.

So, if your dog gets diagnosed with cancer, the doctor says “Oh, they have to have chemotherapy.” You put the dog on chemotherapy, and immediately their health starts to deteriorate because they’re being poisoned, right? The doctor says, “Look how bad the cancer’s getting.” This is a fraud…This is charlatanism. This is con artistry in medicine…That’s what these people are doing. They’re conning pet owners into chemically poisoning their dogs and cats and calling it medicine. But it isn’t. It’s animal cruelty.

If we have to use something that is known to cause cancer – radiation is immunosuppressive and causes cancer – to treat cancer, we’ve failed in the field of healthcare. Period.

The arrogance here, assuming no one might disagree solely because these ideas are implausible, untested, or demonstrably wrong, is pretty astounding. One wonders what kind of cognitive dissonance it takes to convince someone that the entire field of veterinary medicine is so stupid or so greedy that it is willing to overlook simple and obvious ways to prevent and cure cancer. How is this more likely or more reasonable than the alternative, that the small cadre of true believers in these ideas are simply wrong?

The claim that most vets know little about nutrition, and less than pet owners or alternative medicine practitioners who are “self-educated” from internet articles or books by other self-labeled experts with unconventional views, is untrue. While the true experts are board-certified veterinary clinical nutritionists (the vast majority of whom dispute most of the nutritional claims made in this series), all veterinarians have instruction in nutrition and the use of therapeutic dietary manipulations. All veterinarians can, and should, keep up with the clinical literature, which frequently addresses nutrition as a preventative and therapeutic practice.

Undoubtedly, the limitations of time and knowledge, which most vets must split among nearly all major areas of clinical medicine for several different species, does prevent all of us from focusing exclusively on nutrition any more than we can focus exclusively on cardiology, oncology, or dermatology. But we do have and use many resources and experts in the area of nutrition, as in all other areas, to help us maintain an evidence-based approach in this aspect of clinical practice. The training and continuing education vets receive in nutrition is substantial and reliable, and veterinarians are useful resources for animal owners looking for best feeding practices for their pets.

The corollary made in this series to the argument that vets know little about nutrition is that what we do know is worthless because it is tainted by association with the pet food industry. This is just a variety of the shill gambit, in which any information produced by anyone with a potential financial interest in the issue at hand is immediately dismissed as unreliable. While financial bias is a real issue in scientific research, the shill gambit is just a self-serving and hypocritical tool for not dealing with evidence against a claim and for distracting from the lack of evidence for that claim.

The folks in this series who believe conventional nutrition causes cancer and that their preferred unproven alternative approach is superior have no claim to better education in nutrition than the majority of mainstream veterinarians, and certainly less than the veterinary nutritionists who nearly all disagree with most of their claims. The makers of these videos also have their own financial biases since many make their living selling products and services, from clinical treatments to diets to books and videos about nutrition, all of which depend on convincing people their claims are true and undermining the mainstream approach to nutrition and cancer care. Finally, and most importantly, there is no real evidence to support the claims against conventional pet nutrition (as we have already seen) or the claims for the alternatives they are promoting (as we will see shortly).

The claims that conventional cancer therapy is ineffective, does more harm than good, or is even a form of animal cruelty, are similarly untethered to truth or evidence. The other authors here at Science-Based Medicine have addressed the myth that conventional cancer treatment doesn’t work (1, 2, 3). The declining death rates for many cancers are due partly to reduced cancer incidence (contrary to Claim 1 of these videos), but they are also due to improvements in treatments and outcomes. The options of surgery, radiation, and chemotherapy, so maligned in these videos, can prolong life and even cure cancer for many patients both human and veterinary.

And contrary to the propaganda in this video, conventional cancer treatment includes many other treatments as well. Immunotherapy, hormonal therapy, stem cell treatments, and others are available, and new treatments are being developed. Therapeutic vaccines, bone marrow transplants, and other novel therapies are being introduced which will continue to improve outcomes for veterinary cancer patients. Determining the right treatment for each cancer and each patient requires rigorous science, and there will very likely be no “magic bullets” that cure every kind of cancer. However, progress in cancer treatment is being made.

The videos are also wrong in asserting that science-based medicine blindly pushes chemotherapy, radiation and surgery. A recent study, conducted by conventional cancer doctors, has improved our ability to know which women with breast cancer are unlikely to benefit from chemotherapy, and this will change guidelines and practice to improve the treatment of such cancer patients. Reducing unnecessary and unhelpful testing and treatment, for cancer patients and all patients, has become a major goal in human medicine, and there are many of us working to bring awareness of this to veterinary medicine as well. The idea that science-based clinicians intentionally inflict ineffective and unnecessary treatments on patients for financial gain is not just offensive, it’s clearly false.

Of course, the attacks in these videos on conventional thought and practice in cancer treatment are intended to lead up to claims that alternative approaches are better. There is evidence that use of alternative therapies endangers cancer patients and often worsens their outcomes (e.g. 1, 2, 3, 4), so this is a pretty unlikely claim, but let’s finish by looking at a couple of specific ideas from the TAPC series.

Claim 4: Alternatives are better

TAPC proponents claim alternative diets and other unconventional treatments are clearly safer and more effective than conventional nutrition and therapy for cancer. Examples include:

[Cancer cells] all ferment. Take away their fermentable fuels, that’s going to be the solution…When you make radical changes in diet, there are so many examples of cancer remission…No chemo, no radiation, no surgery, just a dramatic dietary change.

[Our dog] was given just a few months to live because of some type of a crazy tumor…So, we really stepped up her diet….really pushing her into a therapeutic ketosis. Within a few weeks her symptoms were gone…We then added in high dose CBD oil…Within a month her tumor went from the size of a very large grapefruit to the size of a grape.

Feed dogs that have cancer with higher fat, lower protein, almost no carbohydrate diets. In other words just the opposite of dry food. We’re seeing cancer, the remission of cancer.

[For cancer] I would do acupuncture. I would do Chinese herbal medicine, absolutely, if they can tolerate it, because some animals can’t, do the right nutrition, and maybe spiritual growth for the family…If all else fails, you talk to an animal communicator and you find out what the animal wants.

In holistic medicine, I think we’re extending lifespans and extending quality of life in a way that conventional medicine is unaware of…“I get them off of their kibble, which I lovingly call “death in a bag” in my practice…We talk over vaccination. I say, ‘Say it with me.’ I make them say it with me ‘No more vaccines.’ So, we repeat that chant, ‘No more vaccines.’

I got involved with essential oils because of my dog having cancer…I learned how to soak a dog in essential oils and since then I’ve become enamored with essential oils as a modality for managing cancer.

I had a case…where this mass was sticking out of its face…I was doing acupuncture, we were doing herbs, and the cat got better for about 6 months…then it started going downhill…[the client]came back in two weeks later and the tumor was 50% smaller…She said “I talked to an animal communicator and the animal communicator was talking to the cat and talking about energy medicine and how to use energy medicine to heal the tumor. And apparently the cat said back ‘Oh, I can do that.’

Sometimes we change the food and the cancer falls off….And you say, “Well, that can’t happen.” Well, it just did.

In the past 22 months…we have seen a 73% success rate in reversing cancer, reducing cancer or stopping tumor growth…We have seen zero metastases in any of the dogs…We believe that is our ketogenic diet…that accounts for this high success rate.

I don’t hesitate for a split second about advocating a raw or at least a home­made diet for an animal with cancer. I try to have owners understand it’s a necessity to expecting that great outcome

We need to know as a profession, as a veterinary profession, that there are food options that can fight cancer. Raw is very important.

This series offers a pretty varied list of prescriptions for cancer treatment: raw diets, ketogenic diets, essential oils, acupuncture, herbal medicine, “energy” medicine, cannabis oil/CBD, pet psychics, and many others. What do these have in common? Primarily two things: They are unconventional, and they haven’t been shown to work. Some of these are plausible but untested for cancer treatment (e.g. ketogenic diets, CBD), others are clearly quackery (e.g. “energy” medicine and essential oils). But regardless of the plausibility or the confidence the participants in TAPC express, none of these therapies have good supporting evidence showing they can treat or cure cancer.

There is an important difference between looking for new treatments, and even being hopeful about their potential, and inflicting unsupported claims on patients while attacking established treatment options. I am interested in the potential for ketogenic diets as a tool in managing cancer based on the very limited evidence available in humans and animal models. However, there are no clinical trials at all in dogs and cats; given these species differ dramatically from rats and humans, it is unreasonable to promise people miracles from this approach without having that evidence.

I am also optimistic about the potential of cannabis products, such as CBD, for a variety of conditions (particularly pain and epilepsy). Several clinical trials are underway in dogs and cats, and I await the results with cautious enthusiasm. However, there is insufficient evidence in humans to recommend cannabis for cancer treatment, and there are zero studies in pets to support claims cannabis is an effective cancer treatment in these species.

These are probably the best of the bunch. Pretty much everything else mentioned as an alternative to the supposedly terrible and ineffective practices of science-based medicine is nonsense. I have followed claims for raw diets for years, and while there is plenty of evidence for their dangers (particularly poor nutritional quality and infectious disease/parasite transmission), there is zero reliable evidence that they have therapeutic benefits for cancer or anything else. Despite hundreds of reviews of many, many clinical studies in humans, it has been impossible to convincingly show that acupuncture is more than a placebo in cancer patients, and as usual there are no relevant veterinary trials. The case for herbal medicine and ludicrous nonsense like “energy” medicine and animal communicators is even worse. There is lots of bluster and confidence in these videos, but at the end of the day they don’t have much of substance to offer pet owners dealing with cancer in their animal companions.

The bottom line

As I said in the beginning, The Truth About Pet Cancer series is a slick bit of propaganda. The producers of the project are effective communicators and manipulators of visual and social media (more’s the pity). While it is easy to find potential personal and financial incentives for the project, I suspect most of the participants are absolutely sincere in their fears about mainstream veterinary medicine and nutrition. I also don’t doubt they believe their own hype about the miraculous alternatives they champion.

Despite all of that, their beliefs about the scope and causes of cancer in pets are at best unproven and more likely false. Their attacks on science-based medicine are unfounded and misleading. And their confidence in alternative therapies is not justified by real scientific evidence. There is much sound and fury here, but it signifies very little.

Pet owners naturally want to do everything possible to prevent and treat cancer in their animal companions. It is unfortunate that this normal drive is misdirected by the misinformation in this video series. As always, I would encourage people facing a cancer diagnosis in their pets to start by finding a veterinarian with experience in cancer treatment, ideally a board-certified veterinary oncologist. And rather than relying on the internet or even the personal experience of individual doctors, I would encourage a frank discussion with your vet about the evidence behind their recommendations. It may sometimes be appropriate to reach for therapies that have not been tested as thoroughly as we might like since the evidence base for veterinary medicine is often thin. But bold claims about dramatic success and no serious risks are not yet justified for any cancer therapy in pets, so these should be viewed skeptically regardless of who makes them.

Here are some reliable resources about cancer care for pet owners that offer real, trustworthy information rather than inflated claims and pseudoscience:



  • Dr. McKenzie has always pursued a wide range of interests both within and outside of veterinary medicine. After completing a bachelor’s degree with majors in English Literature and Biology at the University of California at Santa Cruz, he followed the dream of becoming a primatologist. He obtained a Master’s in Physiology and Animal Behavior and worked for several years in environmental and behavioral enrichment for captive primates. Switching gears, Dr. McKenzie then attended the School of Veterinary Medicine at the University of Pennsylvania and began working as a small animal general practice veterinarian. In the course of trying to improve his knowledge and better educate his clients, he discovered evidence-based veterinary medicine, and he has served as President of the Evidence-Based Veterinary Medicine Association. This has led to numerous opportunities for speaking to veterinarians and the general public about evidence-based veterinary medicine and some of its ideological competitors. Dr. McKenzie has also reached out to the public through SkeptVet Blog, his contributions to the Science-Based Medicine Blog, and media interviews on veterinary medical topics. While working as a practitioner, speaking, and writing, Dr. McKenzie has continued to pursue post-graduate training and completed his MSc in Epidemiology at the London School of Hygiene and Tropical Medicine in 2015. In his sparse free time, Dr. McKenzie enjoys reading, hiking, playing his mandolin, travelling with his family, and sitting on the couch with his dogs watching the hummingbirds and woodpeckers outside his living room window.

Posted by Brennen McKenzie

Dr. McKenzie has always pursued a wide range of interests both within and outside of veterinary medicine. After completing a bachelor’s degree with majors in English Literature and Biology at the University of California at Santa Cruz, he followed the dream of becoming a primatologist. He obtained a Master’s in Physiology and Animal Behavior and worked for several years in environmental and behavioral enrichment for captive primates. Switching gears, Dr. McKenzie then attended the School of Veterinary Medicine at the University of Pennsylvania and began working as a small animal general practice veterinarian. In the course of trying to improve his knowledge and better educate his clients, he discovered evidence-based veterinary medicine, and he has served as President of the Evidence-Based Veterinary Medicine Association. This has led to numerous opportunities for speaking to veterinarians and the general public about evidence-based veterinary medicine and some of its ideological competitors. Dr. McKenzie has also reached out to the public through SkeptVet Blog, his contributions to the Science-Based Medicine Blog, and media interviews on veterinary medical topics. While working as a practitioner, speaking, and writing, Dr. McKenzie has continued to pursue post-graduate training and completed his MSc in Epidemiology at the London School of Hygiene and Tropical Medicine in 2015. In his sparse free time, Dr. McKenzie enjoys reading, hiking, playing his mandolin, travelling with his family, and sitting on the couch with his dogs watching the hummingbirds and woodpeckers outside his living room window.