Are major's ribs pretty visible all the time? That's usually what I go by. No one wants Major overweight, but sometimes pups can burn calories faster than you realise. If his ribs are quite visible, you might want to consider upping the food a smidge. Don't feed him 10 cups a day, obviously! But maybe add another half or quarter of what you feed him now per feeding.

But then, it's up to you, really. Do YOU think he's a little skinny? After all, he's your baby, not ours. Do what you think is right.