try mcdonalds , seriously , whatever he'll eat , protein and fat would be great , but calories would suffice in getting his appetite back , a hamburger ....... possibly the meds have upset his stomach , ask the vet for something like sucralfate ...... I believe mcdonalds French fries saved one of my dogs life ..... he bloated , they were able to save him with a surgery , he lost his spleen and it caused him a heart issue , he wouldn't eat , I got him to eat mcdonalds French fries and he built an appetite off that ........