Hip dysplasia is an abnormality of the hip joint which can cause crippling lameness and arthritis. The cats most commonly affected with hip dysplasia tend to be males of the larger, big-boned breeds such as Persians and Maine Coons. The relatively smaller size and weight of cats frequently results in symptoms that are less pronounced. X-rays submitted to the Orthopedic Foundation for Animals (OFA) between 1974 and 2011 indicates that 24.3% of Maine Coons in the database were dysplastic. The Maine Coon is the only cat breed listed in the database. The hip dysplasia registry (public and private) collected by OFA through April 2015 also showed that there were 2,732 cats that suffered from hip dysplasia, of which 2,708 (99.1%) were Maine Coons. Dysplasia was more severe in bilateral than unilateral cases and with increasing age.