Food sensitivities and intolerance are potentially serious problems that can result in irritated skin, coat and ear conditions or even gastrointestinal upset. dogs that have food sensitivities or intolerance, also called adverse reactions to food, typically experience an abnormal response to the protein in the food. If your dog suffers from adverse reaction to food, it is even more important to feed the right food. Hill's nutritionists and veterinarians developed Prescription Diet® z/d® clinical nutrition especially formulated to support your dog's skin and food sensitivities. In fact, z/d is clinically proven nutrition to help avoid adverse reactions to food. It helps to improve digestion and stool quality with highly hydrolyzed protein. It helps to improve digestion and stool quality with highly hydrolyzed protein. Clinically proven antioxidants are added for optimal health benefits.