Mine is 7 months old and 48 lbs, and short enough not to look skinny at the moment. Yours may just be going through a growth spurt. Mine was skin and bone until about a month ago, and he still doesn't eat as much as 5 cups a day and he is VERY active (plays with other dogs 3-5 days a week for 8 hours each day). So 5 cups a day sounds like it should be enough for yours... So unless it's worms, I would guess it's just a growth spurt. My vet once said that worms can be so easily missed in a stool sample, he would only rule them out if they tested three samples in the same month and all came back negative... Which is a possibitly for my dog's weight gain: even though he tested negative for worms, he was treated for whip worm anyway because it could not be ruled out. He also was neutered and had a food change from dry Nutro to dry Wellness Fish and Sweet Potato with a little of the same canned food. There was a noticable change in his appetite, so I tend to think he just didn't eat enough before. In your case it sounds like your dog is already eating enough, unless worms were missed, or he needs more kibble than my male at the same age... Check the bag, maybe the kibble you feed recommends more?? If not ask about de-worming just in case...my vet said it won't hurt mine if it turns out he didn't need it. Although the reason for mine was recurring bloody diarrhea which may or may not have been food related and could have been a symptom of whip worms. Just a thought if you think he's eating enough but not filling out enough...
