Food sensitivity and intolerance are potentially serious problems that can result in irritated skin, coat and ear conditions or gastrointestinal upset. Hill's nutritionists & 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. -Visible improvement in skin & coat in 3 days -Clinically proven to help normalize stool -Promotes healthy skin barrier -Helps support a healthy immune system