My dog was having problems with food and we had tried quite a few, including another prescription diet, with no luck. He had an ultrasound, which didn't show anything in particular. My vet suggested this particular formula [Royal Canin Veterinary Diet® Canine Hydrolyzed Protein PS dry dog food] and he has been doing really well on it. He will be 13 years old in November and his health has been good and people always compliment him on his beautiful coat.