Just as in dogs, we can predict that the breeds of cats most likely to have hip dysplasia are the larger, heavy-boned breeds such as the Persian and Maine Coon. It is important to note, however, that hip dysplasia can and does occur in any breed and also in non-pedigreed cats, too. Breeders of dogs at risk for hip dysplasia have long used a screening process to try to identify those dogs at least risk of the disease for inclusion in a breeding program. Veterinarians who are orthopedic specialists review the x-ray and the registry then assigns a grade to the animal being examined. Preliminary evaluations can be done on cats under the age of 2 years, but a final certification is not issued until the cat is over 2 years old.
Breeders use the certifications to determine which animals are best selected for breeding.
OFA now reviews and grades hips for Maine Coon cats. Another method of screening cats and dogs for hip dysplasia was developed at the University of Pennsylvania and is called PennHip. This method utilizes a different x-ray procedure designed to measure the degree of laxity, or looseness, in the hip joint. This system is not as readily available to breeders as the OFA system. However, several researchers at the University of Pennsylvania, including Dr. Gail Smith and Dr. Todd Murphy, are one of the few groups looking at hip dysplasia in cats.