INTRODUCTION Lameness is the predominant clinical sign in cats with orthopedic disorders, but because of the cat’s independent lifestyle this is less readily observed in comparison with the dog. Investigation of lameness in the cat has much in common with the dog but there are important differences. Many of the conditions encountered are similar but their significance may differ and there are also causes of lameness that are rarely or never seen in dogs. The goal of the examination should be to formulate and prioritize a list of differential diagnoses; these differential
SIGNALMENT The age, sex, breed, and weight of the cat may give an indication of the type of conditions most likely to be encountered. For example, male (entire and neutered) cats less than 2 years of age are more likely to suffer from fractures and luxations as a result of traumatic incidents2,3. Degenerative conditions such as osteoarthritis or cruciate disease are relatively less common and are typically seen in older cats. Joint and bone neoplasia is also more common in the older cat, although lymphoma is an important exception. There are a few nontraumatic conditions that have a sex predisposition, such as periosteal proliferative polyarthritis, but gender is generally not a major factor. Cat bites and traumatic conditions are more common in young cats, probably because of their territorial aggression and lack of experience of natural and man-made hazards. Breed predispositions are less important in the cat than the dog. This may be because pedigree cats are seen less frequently than their canine counterparts. The morphology of pedigree cats also differs very little from nonpedigree cats so, in contrast to dogs, conformation rarely plays a significant role in musculoskeletal disorders. With the exception of certain inherited and congenital disorders, there are few conditions that are regularly seen more frequently in specific breeds. Body weight may predispose cats to clinical signs of musculoskeletal disease in general and osteoarthritis in particular. One study found that overweight cats were 2.8 times more likely and obese cats were 5.4 times more likely to suffer from lameness visible to owners4.