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.
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.