I guess the doc doesn't want his BUN level getting too high.
Yes, you are right about raw diet - I tried the conversion many years ago though Simba, has 3 teeth - 1 front on top, 1 front on bottom and 1 right side!!!
(He had cogential gum disease as a kitten when I adopted him)
He can not chew, so that's why I started again w/ground raw turkey, and a little ground beef. He immediately gets diahhrea, though, so the quantities now are small.
He eats a combo of Wellness Core, baby food, ground turkey & beef
Also, Lixotinic Vit&Min, meds - Calcitriol, Methimazole
Thanks for the websites - I've seen them and they are very informative.