the food u are feeding will eventually get him sick; hot dog is processed; contains chemicals and too high in fat. please stop asap; he can end up with digestive problems that will cause him to stop eating all together.
if you want you can reset his GI system by feeding a bland diet of boiled ground turkey and oatmeal (no seasoning).
dogs can't resist green tripe ; you can add a teaspoon of canned green tripe from solid gold; they sell it at petco. just mix a teaspoon in with a high quality dog food and he should eat all the food. which dog food have you fed him so far?
try wellness simple solution salmon and rice or lamb and rice; and add some canned green tripe to entice the appetite; this should help.
also have you considered feeding raw; if your dog is totally healthy you might want to check out aunt jeni's homemade dog food; it's meant to be fed raw; but i cook it slightly. maybe you can try it.
http://www.auntjeni.com/
good luck