I am concerned my Sheltie is going to be huge! He is already 20 pounds and only five months old. I have tried measuring him at the withers, but what a challenge. My best guess is he is about 15". this is our fourth Sheltie and I never kept growth records, though one was on the large size, two were within the standard for height. Other than his size, he is a sweetheart. Super outgoing and loves everyone he meets. Always smiling, tail wagging. I just had not planned on a larger Sheltie, though we all know it is a tough breed to breed for sizes!! I might add, he is on Fromms puppy gold and devours it. He has been getting the recommended serving for his weight, which is 1-7/8 cups. Your thoughts?