Two basic types of joint disease afflict people and animals: degenerative joint disease (osteoarthritis) and inflammatory
joint disease (e.g., rheumatoid arthritis). Inflammation may be present in osteoarthritis (OA) as well, but it is not the
central feature, and may wax and wane. OA is a progressive disease where the articular cartilage is slowly destroyed and the
underlying bone reacts with remodeling and production of osteophytes.
Knowledge about OA in cats – prevalence, impact on lifestyle, efficacy of therapy – is less well developed than for the dog.
Since cats have a small body size, and are light and agile, they compensate for orthopedic diseases better than dogs. Cats
are also notorious for hiding signs of illness, especially if onset is insidious, and it is more difficult to interpret signs
of pain or discomfort (Taylor and Robertson 2004).
Signalment and Clinical Signs
Only recently has a study reporting the characteristics of a series of cats clinically affected with OA been published (Clarke
and Bennett 2006). Cats were included in the study (n=28) if they had historical evidence and/or clinical signs of OA, along
with radiographic evidence. The most commonly affected joints were the elbow (45%) and hip (38%). Most cats (22/28) had bilateral
joint involvement. The median age of cats with OA was 11 years (range 3.2-16 years) and there was no gender predisposition.
The average age of cats with OA was also older in other recent studies: 10.8 years (Godfrey 2005), 13.8 years (Godfrey 2002),
and 15.2 years (Hardie, Roe et al. 2002).
Clinical signs associated with OA in cats include (Hardie 1997; Godfrey 2002; Beale 2005; Clarke and Bennett 2006):
2. Reduced activity
3. Anorexia, weight loss
4. Irritability, aggression
5. Restricted ability to do normal activities
6. Inappropriate elimination and constipation
7. Decreased grooming
8. Lameness or stiff gait
Physical exam findings associated with OA include (Beale 2005):
1. Pain on joint manipulation
2. Soft tissue swelling
3. Periarticular thickening
4. Joint effusion
5. Restricted range of movement
6. Muscle atrophy