i've never heard of it in cats either. Would they do both hips at once?
found some info on the 'net: http://www.winnfelinehealth.org/Page...plasia_Web.pdf
Fortunately cats are relatively lightweight and seem to recover from hip surgery pretty well. My Havoc had a procedure in which the head of the femur was removed and he was walking on it fully within a week (with a decreasing limp after that. He's fine now). I just don't know how well a cat with 2 bad hips would tolerate the pain.