[anonymously]

I would stick with the food that the veterinarian that has examined the dog recommends.
If you can’t afford a Rx diet, I’d recommend consulting a veterinary nutritionist to formulate a home-cooked diet that is appropriate for the pet.
Maybe you could just use the prescription food as a base, 1/2 homemade and 1/2 Rx, see what your vet thinks.

http://skeptvet.com/Blog/category/nutrition/
http://skeptvet.com/Blog/?s=prescription+food
Science-based Veterinary Medicine