As long as the food contains sufficient quantities of gluconeogenic amino acids and fat, there is no dietary requirement for carbohydrate in cat or dog rations. However, in feeding trials carbohydrates in the form of starch are well utilised by both cats and dogs and it is a useful raw ingredient.

Carbohydrates in the form of dietary fibre may be beneficial in maintaining normal gastrointestinal function in geriatric patients because of their effects on motility and the water content of stools. They may decrease the occurrence of constipation in animals predisposed to develop it - though few clinical studies have been performed in the dog or cat. Fibre in the diet also reduces the bioavailability of all energy producing nutrients (i.e. fat, carbohydrate and protein) and so should probably be avoided in animals with compromised gastrointestinal function - particularly those with malabsorption.