When meat-eaters ask vegetarians or vegans how we get our protein or nourish ourselves without meat, we can confidently refer them to the Position of the American Dietetic Association and Dietitians of Canada on Vegetarian Diets: “Well-planned vegan and other types of vegetarian diets are appropriate for all stages of the life-cycle including during pregnancy, lactation, infancy, childhood, and adolescence.”
But pet cats and dogs share a common ancestry and belong to the order Carnivora. The very definition of a carnivore is an animal that consumes a diet consisting wholly or almost exclusively of meat. Carnivora includes domestic cats and dogs, ferrets, lions, raccoons and even the giant panda, which is herbivorous. Carnivores are well-suited to a hunting lifestyle. Most members of Carnivora are superb hunters possessing sharp teeth and eyesight, a well-developed sense of smell, and sharp claws. Dogs differ from cats in that they are not strict (obligate) carnivores but are more omnivorous. One of the most complete studies of the daily nutrient requirements for dogs and cats currently available is the 424-page Nutrient Requirements of Dogs and Cats. When considering whether to feed a cat or dog a vegan diet, that reference is especially useful. It acknowledges that there is far greater latitude in ingredient selection for dog foods and quite feasible that they contain no animal products. However, the same is not true for cats, since strict vegan diets, when fed alone, are not nutritionally adequate even though it’s possible that cats will find them palatable. All commercial dog and cat foods should also adhere to the AFFCO nutrient profiles for cats and dogs.
Vegans and vegetarians naturally want to refrain from contributing to animal cruelty by feeding pets meat-based diets. But the pet food industry exists as a by-product of the meat industry itself, and that industry shows no signs of discontinuation. Some people feel that the term “by-product” used as an ingredient in pet foods means that it is of low value or garbage that is not fit for human consumption. It is true that much of the content of pet foods comes from the “4-D Animals” – downers, the dead, the diseased, and dying animals. Pet foods also contain less palatable parts of animals that people do not want to eat. This includes some organ meats, intestines, lungs stomachs, legs, limbs, and sinewy parts etc. What makes “human grade meat” is in large part a culturally based aesthetic rather than anything practical. In other words, we choose not to eat many perfectly edible organ meats or other body parts simply because they gross us out.
As repugnant as we may find all these things, the reality is that cats, dogs, and ferrets can handle greater microbe burdens in their food, most of which is killed by the cooking process. In any case, carnivores or scavenging carnivores (like dogs) would all eat these same body parts in the wild, but probably in less hygienic conditions than those found in a cooked food.
So the question to feed vegan diets to cats, dogs, and ferrets really becomes an ethical concern. We want to have carnivores as pets, so should those carnivores be compelled to eat a diet without animal products even though making one that is nutritionally appropriate is difficult, and some of them may have to subsist on an inadequate diet? We domesticated them, invited them into our homes, and are now faced with the decision – are we trading one kind of animal welfare for another?
Observations About Dogs, Cats, and Other Carnivores In General
Domestic dogs (canis lupus familiaris) diverged from wolves (canus lupus)about 100,000 years ago. Their diets are predominantly meat, but they will eat non-meat foods such as vegetables and fruits. They do however, have some issues breaking down carbohydrates and cellulose in their guts.
Neither dogs, cats, nor ferrets produce amylase in their saliva, which starts the break-down process for carbohydrates and starches. Amylase is something that omnivores and herbivores produce, but not carnivorous animals. This places the burden entirely on the pancreas, forcing it to produce large amounts of amylase to cope with the cellulose and carbs in the plant material. The carnivore’s pancreas does not secrete cellulase to split the cellulose into glucose molecules, nor have dogs become efficient at digesting, assimilating and utilizing plant material as a source of high quality protein. Herbivores do those sorts of things.
Dogs, cats, and ferrets have the internal anatomy and physiology of a carnivore. They have impressive, sharp teeth designed for grabbing, ripping, tearing or shearing meat – all adaptations for a prey-based diet. They do not have large flat molars for grinding up plant material. They have a short gut and smooth colon, which means that food passes through quickly. Plant matter though, needs time to sit and ferment, which translates to having a longer colon, as humans possess.
The carnivorous nature of the cats’ (felus catus) diet has lead to very specific metabolic differences that show up in their nutrient requirements. These differences make cats (and ferrets) “obligate” carnivores, meaning that they rely on nutrients in animal tissues to meet their specific and unique nutritional requirements and that some level of animal meat is required in their diet for survival. Specific nutritional idiosyncrasies of the cat includes increased protein requirements, as well as the inclusion of arginine, B12, vitamin A, methionine, lysine, taurine, carnitine, choline, and arachidonic acid. Taurine, arginine, arachidonic acid, along with vitamin A and other nutrients, are all found in animal meat and are either completely absent or found at much lower levels in plant material. The reality is that while dogs can utilize plant material and eat vegan diets, neither dogs, cats, nor ferrets bodies are designed to eat only plants as are herbivores.
Studies and Articles on Vegan Pet Foods
There aren’t a lot of studies on the long term health effects or appropriateness of vegan foods for pets. There are no long term studies that I could find (10+ years or the life of the pet). Therefore, feeding pets vegan diets amounts to in-home animal testing. There are however, shorter term studies and articles available, authored by veterinarians and veterinary nutritionists:
- Veterinarian Lorelei Wakefield’s peer-reviewed study, published in the Journal of the American Veterinary Medical Association – “Evaluation of cats fed vegetarian diets and attitudes of their caregivers,” found that taurine levels were low in all the cats, but not critcally so. Dr. Wakefield is a vegan who owns a cat who eats meat-based prescription food.
- The American Society for the Prevention of Cruelty to Animals says: “The nutritional needs of dogs and cats are very different. Dogs are omnivores and can do well on either meat-containing or vegetarian diets, while cats are strict carnivores with very precise nutritional needs.”
- The US National Research Council released dietary guidelines for Cats and Dogs in 2003 “Cats are descended from carnivores, and their gastrointestinal system is well-suited to digesting and absorbing nutrients from animal-based proteins and fats. They should not be fed a vegetarian diet because it could result in harmful deficiencies of certain amino acids, fatty acids, and vitamins.. Although dogs may prefer animal-based food, they can survive on a vegetarian diet as long as it contains sufficient protein and other nutrients..”
- Vegan vet Armaiti May advises having a vet monitor your cat’s urine pH, rather than doing it yourself.
Animal Voices (Toronto) covered this topic in 2006 with a round table discussion, involving two local activists whose cats fell seriously ill on a vegan diet
- Gray, et. al., published in JAVMA (Journal of American Veterinary Medical Association) – Nutritional Adequacy of Two Vegan Diets for Cats. The study showed two commercially available vegetarian cat foods (Vegecat KibbleMix and Evolution canned diet for adult cats) to be deficient in several key nutrients.
- Veterinary nutritionist Dr. Julie Churchill says a vegan diet can eventually cause eye lesions and heart valve problems in cats.
- One survey conducted by PETA found that 82 percent of dogs that had been vegan for five years or more were in good to excellent health and that the longer a dog remained on a vegetarian or vegan diet, the greater the likelihood that the dog would have overall good to excellent health. The study, however, also found that vegetarian dogs may be more prone to urinary tract infections as well as a form of heart disease known as dilated cardiomyopathy, which can be caused by a deficiency of the amino acids L-carnitine or taurine.
- Cats tend to form struvite crystals and stones if their urine pH is too low as a result of lower than required protein. Urinary blockage risk is increased. Male cats are especially at risk due to having a narrow urethra.
From these studies I can see that vegan food for pets must be supplemented, which begs the question – how natural can it possibly be? The logic behind claiming that an obligate carnivore like a cat or ferret is healthiest if fed a vegan diet seems rather indefensible to me. And it’s certainly not without some degree or risk for dogs either. While a manufacturer’s statement that thousands of healthy and long-living animals are on their diets is interesting, additional information is needed to support the diets’ nutritional adequacy.
Highly Questionable Claims by Vegan Pet Food Manufacturers
Unfortunately, some pet owners seem to be endorsing what former chiropractor and Evolution Diet pet food CEO Eric Weisman regurgitates about vegan cats. He is often touted as an expert in nutrition even though he was not, as far as I could determine, a medical doctor or veterinarian of any sort. Some of his more outrageous claims about vegan foods and pets are found variously on the internet, where he is prone to making many unsubstantiated claims, including the following (in reference to the Evolution diet):
- “Dogs Live to be 21”
- “Cars live to be 22”
- “Ferrets live to be 13 ½”
- “Evolution Pet Food reverses late stage cancer in dogs and cats, even in those near death.”
- “Vegan diets reverse organ failure”
- “We are observing up to a 40% increase in life expectancy with Dogs and Cats in Human Family Homes.”
- “Wild animals are ground up in pet food”
- “…treats joint, vascular, autoimmune diseases, liver – kidney disorders, cancers, and other internal diseases in sick animals”
- “Meat, poultry, and fish contain radioactive ingredients”
- “Evolution pet food will clear any opacities from a cat’s corneas”
- “Cats are kinder and more loving on a vegan diet” (I suspect that a cat with a conscience would probably not be a cat)
Weisman’s biography describes him as a “former human physician” and a physician in private practice. Instead, he appears to have been a Dr. of Chiropractic, which is not a medical doctor. Along with his education at Ryerson, University of Toronto, and McMaster, he cites 2 Diplomas including a “Doctorate in post-graduate Health Sciences” at what is now Northwestern Health Sciences University in Minnesota. I have no idea how a diploma is also a doctorate. Northwestern Health Sciences U is a chiropractic and massage therapy school. According to news reports, he faced 58 charges, including practicing human and veterinary medicine without a license and animal cruelty and plead out to some of those charges.
Weisman has made this food for approximately 2 decades but hasn’t yet published any proof of his claims. By Weisman’s account, there is no “national test data” either. I could not locate any veterinarian testimonials on any of his sites. Of course, any “studies” Mr. Weisman refers to don’t actually exist, or are simply anecdotal comments from purchasers of his pet food. Where he ran in to trouble with the chiropractic board is when he started reviewing his client’s pets blood chemistries, analysis upon which he’s not qualified to render any opinion. The chiropractic board was hearing complaints that Weisman was keeping his pets in the office, and sometimes did his chiropractic treatments covered in animal hair and without washing his hands. Further compounding his problems with the board, Weisman’s website began offering $50 packages to treat cancer, kidney failure, and dementia, not including the price of up to $275 worth of vitamins and supplements. For $100, pet owners could buy a “Heart Disease Emergency Treatment Plan” that included a 24-hour emergency pager number for Weisman. For one client, Weisman recommended a dog receive caffeine enemas for lymphoma.
Listening to the various podcasts he appears in, he does give a lot of veterinary advice even after being reprimanded for doing exactly that. His soundbites are filed with “woo” from start to finish. On his own site – www.weismannutrition.com, he still claims he is a Dr. of Health Sciences. He cites such terminology as “The World’s Most Advanced Nutrient-Metabolite Procedures for Cancers, Organ Failure, and Systemic Infectious Diseases.” Seriously? What’s a “nutrient-metabolite procedure” and how does it cure or treat infectious diseases? Weisman can’t seen to stop practicing medicine without a license.
In a very revealing and highly entertaining exchange, Eric Weisman runs up against a vegan interviewer with a PhD in Biochemistry, who also isn’t sure what a “nutrient-metabolite procedure” is either, and isn’t afraid to ask him hard questions about his convictions or his claims about his pet food. Weisman doesn’t respond to the really difficult questions, and sends the interviewer, Ian McDonald, a vegan himself, a nastygram after claiming that he is merely a misunderstood visionary, which is an oft-repeated claim by people selling quackery.
In addition to all the above, in 2003 a recall of Go! Natural pet food was conducted due to a number of cases of acute liver failure associated with the food. The underlying cause was never found, but the company manufacturing the food continues to tout it as healthier based on claims about “good” and “bad” ingredients very similar to those made on the Evolution Diet site. Simply claiming something is healthy and natural provides no assurance that it is safe or healthy.
Vegan pet food promoters often sell their food with fear, vague or even fantastical claims. It is the most egregious kind of unfounded fear mongering with no evidence provided to support it.
Even without the unsupportable claims, it’s hard to justify feeding vegan foods to these animals as a mainstay diet. Since I eat mostly vegan, it’s an understatement for me to say that I don’t care for industrial meat production. However, I find it almost as offensive when any food is marketed by misrepresentation. Since Weisman has made a career out of embellishing the benefits of his food and violating the law, I can’t imagine why anyone would think that a properly balanced commercial meat-based food is a worse alternative than what is being promoted.
In one of the MP3s featuring Weisman, he suggests with-holding food from cats if they don’t want to go vegan. Refraining from feeding cats anything else to eat other than their products in order to force them to eat vegan is cruel, IMO. I can’t personally comprehend how we can stop animal cruelty by feeding a carnivore plant matter – we’re really only substituting one form of cruelty for another by imposing our own ethical principles on a species dependant upon us for their welfare.
Even if we can justify feeding dogs an entirely vegan diet, why would we necessarily want to since it cannot be said that vegetable matter is natural for them. And it isn’t clear yet whether a nutritionally adequate vegan food can be made for cats. It may be possible, but there are reasons to doubt it and there is no evidence that cats can be healthy for long periods of time on such a diet. It amounts to deciding which of your conflicting ethical principles take precedence. Do you do more harm supporting the meat industry or take a chance with an animal companion’s health? It seems to me the most ethically straightforward option for vegans is to choose herbivorous or omnivorous pets.