Recovery concerns for a dog with acute renal failure?

My 3-year-old dog has been battling acute renal failure as a result of, as I and the vet highly assume/suspect, toxic dog food. He was in the hospital for five days where we saw his BUN and creatinine decrease significantly. His BUN, at the highest, was in the 80's and his creatinine was in the 3's. I'm sorry, but I do not have access to his exact values. He received fluid continuously over 48 hours and now his numbers are normal. During his illness prior to treatment, he was very lethargic, drank a lot, and lost about 10 pounds because he refused to eat. He's back home to see how he will do without fluids. I'm concerned because he drinks very little and still has no interest in food. He seems scared to eat, but maybe I'm reading into that too much. We've offered him a few different things. He is sleeping and laying a lot as well. Is this normal this early in recovery? I'm just a worried pup owner and I don't know what to expect.

My father-in-law went through this but I don’t know how this applies to dogs. But anyway…He too had problems with water and food and keeping weight on. Even after he got on dialysis this was true. He did better once they got him on a renal diet, which has to be the weirdest diet in the world. Candy is OK, even encouraged if it makes you eat but stay far, far away from a banana. He most liked eggs. Fried, hard-boiled or whatever. He would have several a day and sometimes that was all he could get down. He especially like duck eggs because they are more creamy and also have more protein and calories, and for him, both were good.He did like his hard candy and he hadn’t been a sweets loving person before that. He would occasionally get a hankering for a solid chunk or simple beef. Like prime rib or a roast. Fruits were a big hit. Some veggies like cooked carrots and beets. Sorry, that is all I can remember. He died almost a decade ago. He was 90 years old.