Prescription Diet z/d is clinical nutrition proven to help avoid skin and digestive signs of adverse food reactions in dogs. It's made in the USA with global ingredients you can trust, and was developed by Hill's nutritionists and veterinarians. This nutrition includes natural fiber to help normalize stool. Formulated without additives known to cause food allergies. Also promotes a urinary environment that reduces the risk of developing struvite and calcium oxalate crystals. Please consult your veterinarian for further information on how Prescription Diet foods can help your dog continue to enjoy a happy and active life.