Actually this English Pointer is not old at all. About 5 yrs. But she is skinny as a rail, and eats like a horse. I keep all my dogs Ivomec'ed up, so worms should not be a problem, and see no signs of worms. She has plenty of energy, and seems happy as a lark. I always feed here more than the others, but it just seems to pass thru without sticking. What to do?