Can domestic cats be healthy as vegetarians?

Question

I used to hear that dogs can be given vegetarian dog food, but that cats need meat.

I'm not sure therefore how to interpret the following PETA claim about cats.

Vegetarian Cats and Dogs

If you have been feeding your companion animals commercial pet foods, you may be jeopardizing their health. [...]

Cats are often more finicky than dogs, and their nutritional requirements are more complicated. [...]

James Peden found vegetarian sources of both taurine and vitamin A, plus arachidonic acid, another essential feline nutrient. He then developed veterinarian-approved supplements Vegecat™ and Vegekit™ to add to his recipes. These recipes are probably the healthiest way to feed cats a vegan diet at this time.

What evidence is there for the healthiness of vegetarian cat food? Is it "more healthy" (for the cat), or "as healthy", or "less healthy" than a control (e.g. than some other commercial cat food[s]).

Also, according to this little page, vegetarian cat food seems complicated.

• The cited Vegecat™ and Vegekit™ are "added to his recipes" rather than being pre-bought cat food

• Later it suggests you add "digestive enzymes" to "cooked or processed food"

• Later it says,

  If you decide to prepare your own vegetarian dog or cat food, we recommend that you read Vegetarian Cats & Dogs to ensure that you understand the nutritional needs of dogs and cats. Do not rely on this factsheet for complete information. The book has several recipes and helpful hints. If your library or bookstore doesn’t have it, you can order it from Harbingers of a New Age.

So can you actually even buy, does anyone make and sell commercially, a vegetarian cat-food? Or is this a realm of home-cooked experimentation?

I'm willing to consider answers/evidence which include almost any (non-strict) definition of "vegetarian": even including for example milk or shell-fish; but not meat and meat by-products.

Answer 1

Here's a link to an article about feline diet evolving idiosyncratic needs:

Idiosyncratic nutrient requirements of cats appear to be diet-induced evolutionary adaptations*

The nutrient requirements of domestic cats support the thesis that their idiosyncratic requirements arose from evolutionary pressures arising from a rigorous diet of animal tissue.

Cats can't eat the wrong food without detriment to health. While science can certainly create an artificial food for any living thing with enough time and research, most people don't research a cat food well enough to understand the pros and cons fully.

---

Food manufacturers are held to certain standards. While I'm not sure about the recent developments, historically they bear two main concerns as listed in this link:

The Association of American Feed Control Officials Dog and Cat Food Nutrient Profiles: substantiation of nutritional adequacy of complete and balanced pet foods in the United States.

The first means is by formulating the food so that nutrient levels fall within the ranges as established in the AAFCO Dog and Cat Food Nutrient Profiles.

The second means of substantiation is through the conduct of feeding trials following AAFCO protocols.

Beware that secondary dietary concerns are not enforced (for example there are no dietary restrictions on nutrient density that I know of, leaving them eating far too many calories to satisfy their basic needs).

Commercial pet foods have the main benefit of providing essential nutrients, but they do so (usually if not always) in the cheapest way possible.

Answer 2

There isn't enough evidence to say whether it is safe for cats to be vegetarians.

One study "Evaluation of cats fed vegetarian diets and attitudes of their caregivers" (quoted below) evaluated cats that were fed a vegetarian diet for at least a year, and found that they had cobalamin and taurine levels within the reference range.

This doesn't demonstrate, however, that the cats were completely healthy, or that a cat fed a vegetarian diet for a longer time period would be healthy, or that the cats would . There also might be a selection effect in that cats that experienced health issues earlier on would not be vegetarian for a year. Overall, there aren't many studies assessing the health of vegetarian cats.

Supplementing vegetarian cat food with taurine, cobalamin, vitamin A, and other nutrients is relatively straightforward, but there are some other challenges that are more difficult to overcome:

• cats have short intestines not designed to digest plants
• vegetarian food is more alkaline and can cause cats to have kidney stones, so their urine pH should regularly be checked (Vegan Outreach)

The Vegan Outreach link also says:

A survey of the health of cats on various vegan diets was performed by a veterinary student at University of Pennsylvania and published in the Journal of the American Veterinary Medical Association in July 2006. It showed that most of the cats surveyed on a vegan diet did not suffer from subnormal taurine blood levels and were for the most part in good general health. In summary, more studies are needed to document the health of cats on a vegan diet in the scientific literature.

Wakefield, Lorelei A., Frances S. Shofer, and Kathryn E. Michel. "Evaluation of cats fed vegetarian diets and attitudes of their caregivers." Journal of the American Veterinary Medical Association 229, no. 1 (2006): 70-73. https://avmajournals.avma.org/doi/abs/10.2460/javma.229.1.70.

The purpose of the study reported here was to determine motivation and feeding practices of people who feed their cats vegetarian diets as well as taurine and cobalamin status of cats consuming vegetarian diets.

All cats evaluated had serum cobalamin concentrations within reference range, and 14 of 17 had blood taurine concentrations within reference range.

Two groups of cats and their caregivers from households in which cats were exclusively fed a commercial or homemade vegetarian diet for ≥ 1 year (group V) and from households in which cats were exclusively fed a conventional feline diet for ≥ 1 year (group C) were investigated. All cats were required to have a veterinary practice of record and to have been evaluated at least once at that practice over the course of 1 year.

Blood taurine concentrations were within reference range for most of the cats tested. However, 3 cats had blood taurine concentrations between the reference range and the critical concentration, suggesting that their dietary intake was marginal, but that they were not clinically deficient.

(only 11% of attending veterinarians were characterized as completely supportive of the feeding practice)

Lack of an appropriate assay was the reason that nutrients of concern in vegetarian cats other than taurine and cobalamin, such as arachidonic acid or retinol (vitamin A), were not evaluated.