Nutrition is the cornerstone of good health and wellbeing for pets. There are now many excellent diets to feed pets that are safe and which will deliver everything a pet needs in optimal quantities. For healthy pets, the aim of these diets is to maintain good health and quality of life for as long as possible. When nutritional requirements change in times of illness or disease, the aim is to support the pet on their return to good health, or aid in the management of their disease. In recent years, the development of disease-specific dietetic food has increased. These not only deliver essential nutritional requirements but also have nutritional adaptations to help reduce signs or the impact of diseases and promote recovery. Nutritional management of disease complements other medical management.