Orson has never been what I would call "difficult" to keep weight on, and he doesn't get over weight easily either. He's always been a fairly easy dog to keep at a steady weight. That said, he has dropped 4lbs (from 84 down to 80) since his last yearly. He doesn't look too thin (to me or the Vet) and I haven't noticed him eating less or exercising more. If anything, I expected him to be UP a pound or two since the winter has been so bad, we've laid around the house....A LOT for the last 3 months! He is going to be 9 eek in a little more than a month and the only thing different for the last year is fish based kibble thrown into the rotation. I'm going to cut the fish out of his diet and hope that's all it is. Has anyone else has had issues keeping weight on with a fish based food?