Protein is an important structural substance that constitutes the dog's body. Various tissues and organs of the dog, such as muscles, skin, internal organs, blood, nerves and bones, are all formed of protein as structural substances. The protein content in animals is second only to water. A series of physiological processes such as pregnancy, growth, and lactation in dogs all use specific proteins as their material basis. In addition, protein is also an essential substance for the renewal of various tissues in dogs, and can also be used as an energy substance in the dog's body.

The normal life activities of dogs are inseparable from protein, which must be obtained from food. Under normal circumstances, adult dogs need about 5 grams of protein per kilogram of body weight per day, and growing dogs need about 10 grams. In addition, lactating female dogs and dogs recovering from illness need to increase protein in their diets.