Hills Prescription Diet Canine Z/DHills Prescription Diet Canine Z D Food Sensitivites Clinically proven to help reduce skin & gastrointestinal signs caused by adverse food reactions. How it helps: Hill's Prescription Diet z d Canine is clinically proven to help reduce skin and digestive signs caused by food allergies. Key Benefits Hypoallergenic food formulated with highly hydrolysed chicken as the only animal protein source. Clinically proven to help reduce skin and digestive signs