Cat: why plant-based proteins are not as good as animal-based

Animal vs plant proteins in cats

Very few people know this: on a cat food label, "34% protein" means nothing without knowing their source. Cats digest animal proteins far more efficiently than plant proteins. For some nutrients, they cannot use plant-based sources at all.

The cat is a strict carnivore

Unlike the dog (an opportunistic carnivore), the cat does not produce certain pancreatic enzymes to metabolize carbohydrates. Its liver does not synthesize taurine, arginine, vitamin A, or arachidonic acid — it must find them in its food, exclusively from meat or offal.

The 4 essential nutrients

Taurine

Chronic deficiency causes dilated cardiomyopathy and retinal degeneration (blindness). Found ONLY in animal tissues: heart, muscle, offal. Soy, peas, potatoes contain none.

Arginine

Essential for the urea cycle. Deficiency = ammonia toxaemia fatal in 12 hours. Abundant in meat, absent from grains.

Preformed vitamin A

The cat does not convert plant beta-carotene to vitamin A. It needs retinol (animal form) — present in liver and fatty flesh.

Arachidonic acid

Long-chain omega-6 that cats do not synthesize from linoleic acid. Source: animal fat, egg yolk.

How to spot a good dry food

On the label:

• The first ingredient must be a named meat: "chicken", "salmon", "turkey" — not "meats and animal by-products" (unknown source), not "pea protein" at the top of the list.
• Crude protein ≥ 32%, ideally > 36% for an active cat.
• Taurine listed (added or via offal).
• Plant proteins (peas, corn, soy) can be present as a complement — never as the main source.

Manufacturer tricks

The "splitting"

They divide peas into "yellow peas", "pea protein", "pea fiber" so none exceed meat in the ingredient list. Added together, peas often represent 30–40% of the dry food.

The misleading "protein content"

A dry food at 40% protein can contain 25% plant-based and 15% animal-based. The cat will lose muscle despite a flattering number, because it only uses a fraction of plant proteins.

The cat vegan/vegetarian

Doesn't exist medically. Several studies (Gray 2004, Wakefield 2006) show that even with synthetic taurine supplementation, vegetarian cats eventually develop deficiencies. It's incompatible with their physiology.

The case of elderly and renal cats

Counter-intuitive: sometimes we hear "reduce protein in cats with kidney disease". False for healthy cats. The recommendation only concerns cats with confirmed chronic kidney disease, and even then it's better to reduce phosphorus more than protein itself. Quality (animal, high digestibility) matters more than quantity.

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SokoScan analyses the quality of proteins on each product. A single figure is not enough — look at the Ingredients score. See the best cat dry food.