Domestic cats, like wild cats, are obligate carnivores. This means they require a meat based diet for their nutrition and survival – or at least, they require specific compounds only naturally found in animal products. 

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Why is meat so important to an obligate carnivore?

The main macronutrients in meat are protein and fat. Protein is a very important part of all cats diets; while fat contains the essential fatty acids that cats cannot synthesise themselves.

Importantly, in cats, protein is one of their primary energy sources. Unlike other animals, cats are designed to use protein as their energy source as their bodies are programmed to know they will have plenty available based on them consuming a diet high in protein.

Protein is made up of chains of molecules known as amino acids. These amino acids are used by the body for many functions which include building and repair of damaged cells and tissues, making new proteins and absorbing nutrients. There are 11 essential amino acids that are critical for normal bodily function that cats must get from protein in their diet.

What will happen if a cat doesn’t get protein in their diet?

Without protein cats will likely become malnourished and develop severe health issues. Cats are unable to change their bodies requirement for protein, unlike other species who can switch to using other energy sources or produce more of their own amino acids, cats lack this flexibility which leads to severe health issues.

A lack of protein will often result in cats not getting some or all of the 11 essential amino acids that they require. Well known deficiencies can occur if cats do not get taurine or arginine in their diet. Taurine and arginine are 2 of the 11 essential amino acids previously mentioned. 

Taurine is an essential amino acid that is important for reproductive health, cardiovascular health and vision. The majority of taurine needed by cats is obtained from protein in their diets. Cats with taurine deficiency can have a number of severe health issues; including blindness as a result of retinal degeneration, heart muscle weakness resulting in cardiomyopathy which can be fatal if not treated, and abnormalities with young if they are breeding. 

Arginine is an essential amino acid that cats cannot make themselves. If cats do not get arginine in their diet they can get severe neurological and gastrointestinal signs due to a toxic accumulation of ammonia in the blood.

Does it matter if cats get animal protein or plant protein?

Research is ongoing on how cats can use plant protein in their diets, however we do know some amino acids that are essential for a cat’s normal function can only naturally be found in sufficient bioavailable quantities in animal protein, and this includes arginine and taurine. While it is possible to artificially produce taurine- and arginine-rich plant-based diets, it is difficult and the bioavailability is unclear.

In addition we know cats have a shorter digestive tract than dogs. This means they are less equipped to deal with plant based material. And unlike dogs they break down protein much faster and are unable to adapt when their diet is limited in protein, rapidly becoming unwell when they are deficient in the essential amino acids. As a result, it is a reasonable conclusion that animal protein is an essential component of your cat’s diet to ensure they are not deficient in these essential amino acids, and plant protein alone may not meet your cat’s protein needs. It certainly won’t meet your cat’s needs for other ingredients that aren’t found at all in plant products. But that’s a different article!

What are the signs of protein deficiency in a cat?

The signs of protein deficiency can vary depending on whether there is a specific amino acid deficiency or a more generalised nutritional issue, but can include:

  • reduced body condition and weight loss
  • digestive issues
  • neurological issues
  • vision changes
  • lethargy and weakness 

If you are concerned your cat is unwell or may have a protein deficiency it is important they are seen by your veterinary surgeon as soon as possible. This is so any potential serious health issues can be identified and addressed quickly.

Summary:

  • Cats are obligate carnivores who require a diet high in protein 
  • Cats use protein for many essential bodily functions and as an energy source
  • Some essential amino acids including taurine and arginine can only be found in animal protein sources so animal protein is a vital component of a cats diet
  • Signs of protein deficiency in cats can vary

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