The heart is the most important organ in your pet's body, and factors such as age or weight may affect its function. Poor heart health can affect your dog's life style and happiness.Because the food your dog eats plays an important role in his or her overall health and well-being, at Hill's, nutritionists and veterinarians developed clinical nutrition especially formulated to support your dog's heart health.Hill's® Prescription Diet® h/d® Canine is a complete and balanced food that provides all the nutrition dogs need.