[anonymous]

How old is the dog? If he is a senior, has he had a vet checkup, lab work done?
Annual exam?
Important to rule out disease processes that are just beginning and identify treatment options early on when they will most likely be effective.

Some senior dogs tend to get skinny as they age. Just like people, some tend to get fat, but if you look around, a lot of elderly folks are thin, despite having good appetites and having an adequate diet.

What are you feeding him?