The following is a good link and does discuss the issues of anorexia in these pups. If you can get over that hurdle it's best. I suggest that when you go there, take a little buffet of foods with you so he can have options. I did that with one of my renal pups earlier in the year....surprisingly she opted for Hill's Science Diet kibble! I had all kinds of stuff on the plate....chicken, baby food, veggies, canned dog food...rice and chicken...and all she wanted was kibble! LOL
From the link:
"Acceptance of the diet is a critical issue in PLE dogs, particularly in the most severely
affected animals, which may be anorexic. For each patient, the veterinary care team needs to identify the most palatable diet. Initially, it might be more important to feed a less optimal diet that the dog will be interested in eating, and progressively transition to a more desirable diet."
http://www.bli.uci.edu/conti2013/Gaschen_text.pdf