Prescription diets are positioned as nutritional intervention for diagnosed conditions such as urinary, kidney or digestive disease, usually requiring a veterinary prescription and follow-up.

Functional foods address subclinical or preventive needs such as hairball control, sensitive digestion or weight management, and healthy cats can use them day to day.

Using a functional food in place of a prescription diet can delay treatment of a diagnosed condition, while feeding a prescription diet to a healthy cat may not match its needs.

A cat already showing symptoms should be examined first, with the veterinarian deciding whether a prescription diet is needed and how often to recheck.