Vegetarian and Vegan Diets for Cats: Why Vets Advise Against Them

By Tailwisp Editorial TeamUpdated October 20, 20264 min read

Many people choose to avoid animal products for ethical or environmental reasons, and some wish to extend that choice to their cat. It is a sincere concern, but it runs into a biological fact: cats are obligate carnivores. This guide explains why, what the risks are and how to approach the question responsibly.

What obligate carnivore means

Cats evolved to eat prey. Over millions of years, they lost the ability to make several nutrients that other animals produce themselves, because their prey supplied them. As a result, cats need certain compounds from animal tissue, or from carefully supplemented diets. They also use protein for energy in a way dogs and people do not. See how much protein do cats need.

Nutrients at risk

• Taurine. Found only in animal tissue. Deficiency causes dilated cardiomyopathy, retinal degeneration and blindness, and reproductive failure. See taurine: why cats need it and hypertrophic cardiomyopathy in cats.
• Arginine. Needed to remove ammonia. A single meal without it can be dangerous.
• Arachidonic acid. A fatty acid found in animal fat.
• Preformed vitamin A. Cats cannot convert plant carotenoids.
• Vitamin B12 and niacin. Mostly from animal sources.
• Methionine and other amino acids. Plant proteins are lower in some.
• Urinary effects. Plant-based diets may make urine more alkaline, which can raise the risk of struvite crystals unless the diet is formulated to acidify it. See cat urinary diets explained.

What the research shows

Surveys of owners who feed vegetarian or vegan diets report cats that appear healthy, and some studies suggest cats can maintain normal blood values on well-formulated plant-based foods. But the studies are small, often rely on owner reports and do not follow cats over many years. Homemade vegetarian diets, in particular, have been found to be deficient. The risks, if something is missing, may take months to show, and can be irreversible, such as blindness from taurine deficiency. Most veterinary organizations therefore advise against vegetarian or vegan diets for cats.

If you are still considering it

1. Talk to a board-certified veterinary nutritionist, not just a pet shop or website.
2. Choose a product tested for nutritional adequacy, with feeding trials, and not a homemade recipe from the internet. See cat food aafco statement explained.
3. Follow the feeding guide exactly, and do not mix in unbalanced foods.
4. Monitor your cat closely: weight, coat, energy, eyes, urine and stool.
5. Schedule frequent checkups, with bloodwork, taurine levels and urinalysis. See cat blood tests explained.
6. Stop and consult your vet if there is any sign of trouble.
7. Never feed kittens, pregnant or nursing cats, or sick cats a plant-based diet.

Homemade is riskier

Homemade vegetarian diets for cats are particularly hazardous. Without precise supplementation and testing, deficiencies are likely. See homemade cat food safety.

Cats and eggs and dairy

Some owners feed lacto-ovo vegetarian diets that include eggs, which are high-quality protein, and dairy. Eggs are fine cooked, but cats are often lactose intolerant. See can cats eat eggs and can cats drink milk. Eggs alone do not meet all needs.

Other ways to reduce your impact

If your values concern animal welfare or the environment, there are options that keep cats healthy:

• Choose foods from companies with ethical sourcing, or made with sustainable ingredients.
• Use by-products, which reduce waste. See by-products and meals in cat food.
• Avoid waste. Buy sizes you can finish.
• Consider foods made with novel proteins, such as insect protein, or cultivated meat as it becomes available. Check testing.
• Support spay and neuter programs and adoption to reduce suffering. See when to spay or neuter a kitten.

Do not make your cat the experiment

Your cat cannot tell you if something feels wrong. Prioritize its health, and work with a professional.

Talking to your vet without judgment

If you already feed a plant-based diet, be honest with your vet. They can order the right tests, check taurine and vitamin levels, and help you decide what to do. A good vet will respect your values while protecting your cat's health, and can suggest the safest middle path.

Signs to act on quickly

Take your cat to a vet promptly if you notice a dull or thinning coat, rapid breathing, weakness, tripping over objects, dilated pupils, or a sudden change in eating. Early testing can catch a deficiency before damage becomes permanent, and going back to a complete animal-based diet usually helps if started in time.

When to see a vet

See a vet if your cat has lethargy, weight loss, poor coat, vision changes or breathing difficulty. Use the US vet directory to find a clinic.

This article is general educational information, not veterinary advice. Every cat is different. If your cat is unwell, or you are unsure about a symptom, diet change or medication, contact your veterinarian.