All my dogs have filled out around the age of two. Actually Arabella just turned two a month ago and is filling out now. My hubby even noticed that the other day. Thor was 73 lbs for the longest time and then all of a sudden not long after he turned two he filled right out and went up to 87 lbs. Star did the same thing.She was my first, I thought she was going to be a small boxer and then around the time she turned two she filled right out and gained 12 lbs! Since your boy is 80 lbs now he's going to be a big boy!