That is weird. I can get that just about anywhere such as PetSmart and Petco. Also the Vet's office my wife works at doesn't precribe cat or dog food. Anyone can go there and Buy Hill's Science Diet cat or dog food.
That's weird cause i just went to petco, and they said they sell hill's petfood, but that the a/d petfood was by prescription only. Called my vet and he said he'd get me a prescription for it, but i won't be able to make it to him anytime soon.
Many vet's offices will sell you a small can of Hills A/D without a prescription if you tell them it's for a gecko slurry recipe. You can substitute a small can of high calorie, high protein cat food (pasteurized) if you can't get the Hills.