This posts, and many of the notes on it, are bothering me. Ladies, gentlemen, esteemed colleagues from outside the confines of the gender binary; gather ‘round. Let’s throw some science in this joint.
1. Humans. Humans are not cats. Humans are not dogs. One would think this obvious, but people have a tendency to attempt such interspecies comparisons when discussing diet. Humans are order omnivora; we have essentially evolved in a manner that attempts to give us as much dietary flexibility as possible. We do, however, require a substance called B12 (or cobalamin), which is extremely important for brain and nervous system functions, as well as the synthesis of DNA and the construction of red blood cells. We cannot produce this vitamin ourselves–no animal, plant, or fungus can. The enzymes used in cobalamin production are essentially unique to bacteria and archaea–some species of which hang out in the digestive tracks of other animals. We get cobalamin in a roundabout way from fish, shellfish, meat, eggs, milk, and dairy products. While there is no naturally-occurring, vegan source of the vitamin that has been demonstrated effective in a human study of statistically significant sample size, effective synthetic forms do exist and can be used as a substitute. Cyanocobalamin is one of the most common and is frequently found in fortified foods and vitamins. In short: Humans are omnivores. Humans have evolved for dietary flexibility, including viable vegetarianism. Humans did not evolve for veganism (be extremely suspicious of people who tell you that we did, as they are lying), but due to modern technologies, veganism is also a viable diet that humans can thrive on, should they so choose.
2. Cats. Cats are order carnivora. Cats require (amongst other things) an amino acid called taurine. We’re not quite sure how, exactly, but we know that it’s extremely important to feline heart wall tissue, retinal tissue, and brain tissue amongst other things. Cats cannot manufacture their own taurine, and must get it from other sources–primarily shellfish, fish and meat. Taurine breaks down when heated, so feeding your cat a home-cooked diet rich in this foods is also not necessarily a good idea (talk to a vet). Secondary (read: SUPPLEMENTARY. NOT A SOLE SOURCE OF TAURINE.) sources of taurine for cats include dairy, eggs, and seaweed- or yeast-based taurine supplements. In nature, cats don’t really need to worry about getting enough taurine, because (as you may have noticed), taurine sources are indeed the things that cats tend to catch and eat. However, a cat that lives in a human household is dependent on humans for food, and sometimes humans are utter fucktrucks. In short: Cats are obligate carnivores. Their primary source of nutrition is meat. They must eat meat, preferably as close to raw as possible. They have digestive tracks designed for digesting meat. There are vegan/vegetarian cat kibbles on the market. Do not buy them. Your cat is neither vegan nor vegetarian, and if you adjust their diet as if they were, you are a terrible person who is harming and possibly killing your pet. You suck. End of discussion.
3. Dogs. Dogs are slightly more nuanced here. They are facultative carnivores–meaning that they optimally should eat meat, but can survive on other things if resources are scare. Dogs also need the amino acid taurine, but can technically manufacture it themselves if the proper building blocks are in their diets. They also need vitamin D–D3 is preferable, but D2 can be used to some degree. Dogs are somewhere between us (the true omnivore) and the cat (the true carnivore). A vegan or vegetarian diet will keep a dog alive, certainly, but is unlikely to allow your pet to thrive as it lacks the recommended nutrients. You should probably be feeding your dog meat. The exception here–some dogs are allergic to conventional dog foods, or find symptoms of certain diseases alleviated by vegetarianism. In this case, a veterinarian (not you, layperson, I mean an actual trained veterinarian) may determine that the benefits of putting your dog on a vegetarian/vegan diet outweigh those of feeding your dog meat. This is relatively rare, but does occasionally happen. And no, actually, the oldest dog is not vegan–Bramble is the only dog on this list that I found had some indication of veganism. The oldest dog on record is an Australian Kelpie named Maggie, who was not vegan. It is more likely that Bramble lived that long despite the veganism, not because of it. In short: If a vet thinks that your dog may be allergic to dog food/require a special diet and recommends you try feeding it a vegetarian/vegan diet, listen to your vet. Otherwise? Dogs are carnivora. They do need vegetables and other sources of nutrients, but their optimal fuel, as it were, is meat. Your dog needs meat to be happy. Fucking feed your dog.
Now, I did manage to find two veterinarians who disagree with every other study I dug up and the American Veterinary Medical Association. Their articles are here and here. They don’t really have sources, and are essentially wholly dependent on anecdotal evidence (“my dog is a vegetarian and hasn’t died!”), but for those of you data cherry-pickers reading this, there you go.
As a rule, dogs and cats need meat. If that makes you uncomfortable, that is your problem, not theirs. If you try to implement a vegan or vegetarian diet for your pets because you implemented one for yourself, you shouldn’t have those pets. That is animal abuse. (By the way, those of you not feeding your cats and non-allergic dogs the food they need to survive and thrive? What the fuck is wrong with you? Do you not love your pets?)
TL;DR If you do not want a pet that must be fed meat, you should under no circumstances acquire a cat or a dog. Thank you for your time.
