Proteins consist of 23 amino acids, 13 of which are naturally created within the body. The other 10 "essential" acids are provided by diet. For pets, the best essential acid sources include foods made from animal proteins like meat or meal, rather than vegetable proteins, such as corn gluten or soy products. Certain types of proteins, such as raw eggs, contain the enzyme avidin, which causes skin and hair problems and should be avoided.
Fats provide energy, help vitamin absorption and provide essential fatty acids. Without the correct balance, pet skin tends to be greasy and susceptible to inflammation. A lack of essential acids also leads to dry fur and hair loss. Pet foods high in Omega-3 acids - such as fish oil - promote skin health.