That's the thing... BOTH times we had him in for surgery we've insisted on doing bloodwork to find out what was going on. They told us both times that there was nothing that they found to give us any answers. We just take it easy on him now. It's so terrible because I used to take him on long walks and now he can only walk a few blocks before he slows down so we can take a break because of his hip. And about the food we feed him... we've been feeding him Nutro since the day we got him. I just can't wait to get him to the vet. The day isn't coming soon enough. I don't know how much more my vacuum can take haha