Proteins / Amino acids

February 18, 2026

Proteins are made up of different amino acids; amino acids are, as it were, the building blocks of proteins. Proteins can be divided into simple proteins (which consist exclusively of amino acids) and complex proteins (which contain, in addition to a simple protein, a molecule that is not a protein).

The intestinal wall cannot absorb proteins because they are too large. Therefore, proteins must first be broken down into smaller pieces—the aforementioned amino acids. The amino acids can then be absorbed through the intestinal wall.

Proteins have various functions in a dog’s or cat’s body. Proteins are needed for:

The skin and coat: the skin and coat consist mostly of proteins. Proteins are the basic components of the skin, coat, and nails.
Body tissue/connective tissue: the body’s connective tissue consists largely of collagen, a protein.
The muscles: various proteins are needed for muscle function.
Food digestion: the enzymes needed to digest food are protein molecules.
Hormones: various hormones in the bodies of dogs and cats consist of proteins.
Transport: proteins in the blood are responsible for transporting substances.
Acid–base balance: in addition to their function as transporters, proteins in the blood are also needed to regulate the body’s acid–base balance.
The immune system: antibodies that protect the body against harmful microorganisms from outside consist of protein molecules.

When you consider the functions of proteins described above, you can probably understand that proteins are essential for dogs and cats. Without proteins, dogs and cats cannot survive.

However, not all proteins/amino acids are essential for these animals. Amino acids can be divided into essential and non-essential amino acids. Dogs and cats must obtain essential amino acids through their diet. A dog’s or cat’s body can produce non-essential amino acids itself from other nutrients. Below you will find the essential amino acids for dogs and cats:

Essential for dogs	Essential for cats
Arginine	Arginine
Histidine	Histidine
Methionine	Methionine
Phenylalanine	Phenylalanine
Threonine	Threonine
Isoleucine	Isoleucine
Leucine	Leucine
Lysine	Lysine
Tryptophan	Tryptophan
Valine	Valine
	Taurine

A dog’s protein requirements differ from a cat’s. Dogs need less protein than our little house tigers. In addition, cats are obligate carnivores, which means that certain essential proteins cats need are found only in animal-based materials (meat).

The dietary need for protein does not depend solely on species. An animal’s life stage also affects its protein requirements. Young animals that are still growing, for example, have a greater need for protein than adult animals. Pregnant, lactating, and working animals also have higher protein requirements.

Proteins can come from plant-based or animal-based materials. Animal proteins generally have a higher biological value than plant proteins. This means that animal proteins contain more essential amino acids, in amounts that correspond more closely to a dog’s or cat’s amino acid requirements, than plant proteins do (this does not mean, however, that plant proteins are not useful for dogs and cats).