This process often breaks down after a year or more. More recently, some veterinarians have had success with simply removing the head of the femur, thus eliminating the source of the pain. This is also considerably less expensive and requires far less post-operative care than hip replacements. While it sounds hideous, the existing musculature holds the remaining stump of the femur in place, allowing relatively pain-free movement, although no longer an even gait. Occasionally removing small muscles, in a procedure called pectineus myotomy will help.
Some drugs lessen the pain.
In older animals, 8-10 years old, restricting exercise is often useful in reducing pain. My concern has to do with the number of breeders in the past year that have mentioned to me their problems with limping and sensitive hindquarters. A defect like this can spread quickly through a population where only a few top lines are being used and the offspring being interbred. The testing mode of clearing dog breeds adopted by dog fanciers can be used by the cat fanciers as well. More practically, the recognition by all responsible breeders that this can become a major problem will be the first step in clearing and prevention.