Vegan Cats?

The practical and ethical problems of feeding cats a vegan diet have been fairly contentious issues among both veterinarians and vegan activists alike and I myself have jumped into the fray a number of times. While reasons vary among those that advocate or are interested in the idea of animal product-free diets, most express ethical reasons and the desire to avoid contributing to animal slaughter. These advocates claim that cats can get all their nutrition from a properly formulated vegan diet and point to their own personal stories of cats that have lived long term on a vegan diet. The other side claims that cats are obligate carnivores and need meat to survive and often cite personal anecdotes of cats that developed medical problems.

So what does the published science on this issue say? A little bit, but not a whole lot really. An early study from 1992 touched on the issue but its findings are not too impressive scientifically (and sound pretty cruel), notably that cats fed a potassium deficient diets developed a muscle condition typical of potassium deficiency, while cats given supplemental potassium did not develop the condition. Another study in 2001 from Germany titled, “A field study on the nutrition of vegetarian dogs and cats in Europe”, was not encouraging. However this study only looked at eight cats and is at best preliminary.

A 2004 study published in the Journal of the American Veterinary Medical Association (JAVMA) examined the nutrient content of two commercial brands of vegan cat food (Evolution Diet and Vegepet) and found them to be lacking in key nutrients. With its small sample size this study is hardly a slam dunk for those that argue against the idea of vegan cat food but it is worrying nonetheless. The manufactures of both foods responded that they felt that it was likely the result of a mixing error at the factory. But if researchers found such an error in two independent products it leads one to wonder how often such mixing errors occur. The makers of Vegepet promised to look into it and reformulate. The owner of Evolution Diet, Eric Weisman, for his part dismissed the finding altogether as unimportant.

I would be amiss if I were to not also mention that Mr. Weisman has had a history of shady conduct. Aside from lying about the benefits of his products and practicing medical quackery, he has also been accused of some not-so-ethical treatment of animals. And for a taste of Weisman’s argument style listen to his teeth-grating interview on The Vegan Option podcast. Take it for what you will but he certainly doesn’t sound like someone I would trust.

A 2006 study titled, “Evaluation of cats fed vegetarian diets and attitudes of their caregivers”, found that most of the cats in the study were quite healthy. However the sample size was on the small side (34 cats in the vegetarian diet group) and the only objective measures taken were cobalamin and taurine levels. Ian MacDonald (with guest Erin Red) of The Vegan Option podcast speaks with the lead author of this last study in what I consider to be one of the best examples of engaging the issue for a popular audience in their episode Cats: Can they be vegan? and further explores the issue in the follow-up episode Cats: Ethics.

Aside from micro-nutrient balance, the main medical issue that comes up when discussing feeding cats a commercially formulated vegan diet is that of urinary tract obstruction from the formation of small struvite crystals, particularly with male cats. Dr. Armaiti May explains,

Cats on a vegan diet can develop abnormally alkaline (high pH) urine due to the more alkaline pH of plant based proteins in comparison to the acidic pH of meat-based foods which cats have evolved to eat. When the urine pH becomes too alkaline, there is an increased risk of formation of struvite (also known as magnesium ammonium phosphate) bladder crystals and/or stones. Calcium oxalate stones can also occur, but these do not occur if the urine is too alkaline, but rather if it is too acidic. Such stones can create irritation and infection of the urinary tract and require veterinary treatment. In male cats who form such crystals or stones, they can suffer more severe consequences than simply irritation or infection of the urinary tract because the stones can actually cause an obstruction of the urethra so the cat cannot urinate. This is a life-threatening emergency requiring immediate veterinary care…

Thats about it, a little bit of published science and a whole lot of anecdote. So where does that leave us? I myself have serious reservations about feeding cats a vegan diet. I simply don’t think that we have enough information or research. It appears that many cats do quite fine on a vegan diet for much or all of their life. But there also appears to be a potentially serious health risk to a certain subset of cats. Perhaps better food formulations are all that’s needed to do the job, maybe not. And if not then perhaps alternatives such as farmed sessile bivalves or insects may be a route to reduce suffering.

I don’t really have any solid answers here. All I can say is, think critically and think compassionately.

Further Resources:

Cats: Can they be vegan? on The Vegan Option

Cats: Ethics on The Vegan Option

Vegan Cats & Dogs with Jed Gillen, Author of Obligate Carnivore on Animal Voices

Vegan Pet Food: A Discussion on Animal Voices

Evolution Diet – Selling Food with Fear and Lies by Skeptvet

Evolution Diet Update: Selling Food with Fraud by Skeptvet

Mr. Eric Weisman, Promoter of Evolution Diet, Finally Prosecuted by Skeptvet

Eric Weisman Gets Fine and Probation for Violating Court Order by Skeptvet

18 Responses to “Vegan Cats?”

  1. Kevin Says:

    Great article. Is there a similar one for dogs? I personally don’t like the idea of feeding pets meat, yet would be reluctant to keep a pet on a diet that may make them unhealthy, and this is why I’ll probably never own a cat, despite loving them. It becomes a completely different debate, of course, when you already have a cat, whether they are ‘vegetarian’ or not.

    • skepticalvegan Says:

      I may one day write a post about dogs as well. There is more published science there and as far as Ive researched dogs generally fare better on a vegan diet than cats.

    • nightrabbit Says:

      Have you considered getting a rabbit for a pet? Cuddly animals that are love lots of exercise and naturally vegan. Certain old school rabbit breeders may suggest yogurt for certain digestion ailments, but I find that a diet of a wide variety of leafy greens, at least 80% timothy hay, and a good quality pellet food is better for digestion issues.
      In other words, stick with a good healthy diet, and you won’t have those ailments.

      Larger breeds are generally more mild mannered and gentler. Smaller breeds are more mischievous, active, but less cuddly. Reaserch their care and check to help you find a shelter bunny, should you decide it’s the pet for you.

      • Aleksander Kamil Modzelewski Says:

        At the risk of furthering thread necromancy, two words: animal rescue. As a foster carer I’ve had dozens of cats, and several permanent ones, and the only ones that were intentionally bred were from rescues from the worse-than-usual breeders.

        Some animals can be reintroduced to the usual environment, but in case of domesticated species (and, rarely, the more wild ones too — especially when chronic illness is involved) it’s either impossible or impractical or actually disastrous to the environment (thanks to humanity’s general irresponsibility around cats, they end up hugely destructive if outgoing, especially if that’s their primary food source).

        By all means rescue rabbits or rats (rats are awesome! — though do occasionally eat meat) but as long as we breed animals or otherwise create unstable ecosystems, avoiding a certain species is mostly a comfort thing (being a vegetarian or vegan carrying a bag of chicken hearts can be rather unpleasant), not an actual solution.

  2. Ms Vanilla Rose Says:

    Interesting. Did anyone get back to the makers of Vegepet to see if they followed through on their promise?

  3. shanepbrady Says:

    All our dogs (7 in total) have been on a vegan diet for years. We started because our first dog had allergies, and in the process of trying to find out if he had a food allergy, we switched to a veggie skin diet, which happened to be vegan. Since our other dogs have a predisposition to allergies, we kept it up. I haven’t found anything that a dog needs that isn’t found in regular vegan food.

    We’ve not had such luck with cats. We tried a brand claiming to be vegan and a complete solution, but it made them spit up food, so e had to go back normal cat food.

  4. Kylie Says:

    I just avoid the whole thing by not having pets. My daughter has been haranguing me for a dog. Maybe I’ll try to steer her toward a naturally herbivorous creature…

  5. 지나가다 Says:

    Cat ‘s hair falls out.
    I think that the cat is fed a small fish.

    • 지나가다 Says:

      Calcium-rich small fish that can be eaten with bone. it is good.

      Originally, the cat does not eat vegetables at all.

  6. 19peace80 Says:

    Pet food is made from the unwanted scraps and trimmings from the meat industry that exists first and foremost to serve humans; as long as humans eat billions of animals per year, these byproducts will continue to exist no matter what we feed our pets.

    • The Old Punk Says:

      Pet food is not made from unwanted scraps and trimmings. Around 50% of an animal ends up as unfit / unwanted for human consumption. I would hardly call that a byproduct, it is an inherent part of the economics of meat production.
      Without the meat-based pet food industry, meat for human consumption would become far more expensive. Basic economics dictates that this would lead to a massive drop in demand for meat, with a concurrent drop in the number of animals reared for human food.

  7. Dawn Says:

    Cats do not have the necessary enzymes to break down and therefore utilize carbohydrates. They convert protein into energy. If your cats spit up the vegan diet, it is because they could not digest the food. A bunch of undigested food in the tummy, yet still hungry.

  8. Trudy Says:

    We do a half and half diet using Ami vegan and regular kibble. She likes it and does OK. If we increase the vegan food, she throws up. Been on this diet for five years. We feel like it’s better to avoid animal products, but rescued this cat and feel obligated to care for her. We’re doing the best we can.
    We have four vegan rescue dogs. Almost ten years now. We make our own food.

  9. Real Vegan Food « Pythagorean Crank Says:

    […] yes! This isn’t totally off the radar, I do know at least one “bivalvegan” and Skeptical Vegan often brings this up as a solution for domestic obligate carnivores. But these examples are […]

  10. Compassion or Controversy: Cats and Vegans | Says:

    […] For more great articles, check out these links: […]

  11. Feeding my Cat, Ethics, and Compromise – JaxxBlogs Says:

    […] In the two months since I’ve decided to transition toward veganism, the question of what I will feed my cat going forward has been on my mind.  I’ve done a lot of thinking on this and research.  Cats are carnivores, I’m not comfortable feeding her vegan “cat food.”  On doing research on this, I haven’t come across enough evidence that feeding cats vegan “cat food” is a wise decision to make, even if the formulations contain the right nutrients.  Anecdotes of some people feeding cats vegan “cat food” and them not getting ill are not …. […]

  12. Luis Tovar Says:

    You need to revise your thoughts. A vegan diet can be healthy for cats and dogs:

    “This article comprehensively reviews the evidence published to date from four studies that have examined the nutritional adequacy of vegetarian diets for cats and dogs. To obtain additional information, we surveyed 12 pet food companies detailed in the most recent study. We also examined the nutritional soundness of meat-based companion-animal diets, and reviewed the evidence concerning the health status of vegetarian, carnivorous and omnivorous companion animals. Both cats and dogs may thrive on vegetarian diets, but these must be nutritionally complete and reasonably balanced. Owners should also regularly monitor urinary acidity, and should correct urinary alkalinisation through appropriate dietary additives, if necessary.”

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