Or try some alfalfa--I've used it with our elder buns to keep their weight up. Ours are all rescues, so we don't know much about their past either. We've had Bambi for more than 10 years now and were told she was around 5 when we rescued her from the "shelter" and she is starting to look old. When you can afford it, I'd find a vet that a rescue uses that is rabbit savvy as I think yours at Petsmart did not sound all that good to us.
