My sweet peanut, who I adopted 15 years ago is not doing well. Few weeks back, we brought him to the vet because he stopped eating. He had four teeth removed because they were infected. Took him a few more days and he finally ate a spoonful of calorie supplement from the vet. He went down to 9lbs from his normal 18-19 lb self 

. Now he has days where he eats a whole can of food and other days he won't eat. Nothing else we can really do for him. Anyone else been in a similar situation? I hate to see them get old.