Pet owners are more concerned with providing dogs and cats with the best in health care and nutrition; progress in the field of nutrition has generated an improved understanding of canine and feline dietetics.The main role of feeding dogs and cats is to provide ingredients that satisfy the nutritional needs of the animal organism. The classic concept of nutrition and feeding science is that of guaranteeing adequate nutrient intake in order to avoid deficiencies, and to satisfy energy requirements for the various physiological stages (growth, adulthood, old age, etc.).Nowadays domestic animals increasingly have lifestyles and risk factors that are similar to those of their owners: the average age keeps increasing, and physical and mental stress is more evident. At present, pathologies such as osteoarthritis, skin diseases, allergies, cancer, intestinal infections and others are more frequent in domestic animals than in the past.Correct management of feeding is crucial for guaranteeing the best well-being for the animal, and pet owners now seek a long and healthy life for their pet and look to nutrition to achieve this target. So numerous improvements in companion animal nutrition have resulted in the development of a wide array of foods that provide complete and balanced nutrition. Pet food manufacturers emphasise product microbiological safety and quality parameters as well as traceability. Moreover, the pet food industry has developed several products known as "dietetic" with the aim of guaranteeing a wholesome diet for specific pathological conditions such as renal failure, diabetes, heart failure, food allergies and so on. But now research in companion animal nutrition as well as in human nutrition is moving from the concept of adequate nutrition, to cover nutritional requirements, to the concept of optimum nutrition. In this regard there is a growing range of scientific evidence that diet and specific foods play an important role in the prevention of many pathological conditions and improve the physical and mental well-being of the animal.Functional foodSeveral scientific studies claim that some foods and their components have these beneficial effects that go beyond the classic concept of nutrition. This new research field has led to the coining of the term "functional food", which identifies those foods that have been shown to have positive effects on specific functions of the orga-nism, in addition to the usual nutritional effects, in order to…