Arthritis in cats

Arthritis denotes inflammation or infection of a joint. There are many types of arthritis and their causes; such as 'wear and tear' degenerative disease, infection (bacteria and viruses), invasion of a joint by cancer and congenital (hip dysplasia, etc).

Osteoarthritis

Osteoarthritis (OA) or degenerative joint disease (DJD) is a rare disease in cats compared with dogs and humans (where it is called rheumatoid arthritis). OA usually affects younger cats (<10 years) and as young as 6 months of age and caused by congenital and developmental disorders (such as OCD (osteochondritis dissecans), hip dysplasia, luxating patellas, etc). Osteoarthritis can be a primary (rare) or secondary (common) disorder and is usually confined to one or a few joints.

Polyarthropathy / Stomatitis in kittens

A well-recognised syndrome in kittens, Polyarthropathy / Stomatitis, is usually caused by viruses (such as calicivirus) and rarely, immune reactions to vaccines. Polyarthritis / stomatitis is a relatively common syndrome in young kittens believed to be an immune-mediated complication of infection with feline caliciviral infection. Cats usually exhibit a transient fever (>39^oC) and shifting-leg lameness associated with pain on moving around. Affected cats/kittens usually have oral lesions as well as joint soreness and recover from illness 3-4 days later. A second round of soreness occurs 10-14 days later, associated with immune-complex deposits in the joints. This second bout occurs without the presence of oral lesions. Anecdotal evidence also exists that this syndrome occurs in cats that have been vaccinated within 1 month with caliciviral vaccines. A diagnosis may be made based on joint aspiration (presence of neutrophils in joint fluid). The stomatitis which is apparent in this syndrome should not be confused with the lymphocytic plasmocytic stomatitis in older cats that is a more chronic oral disease. Treatment is restricted to alleviation of symptoms; including broad-spectrum antibiotics such as clavulox and anti-inflammatory drugs such as meloxicam.

Septic arthritis

Infectious arthritis is most frequently associated with bacterial agents such as staphylococci, streptococci, and coliforms. Causes include hematogenous spread or penetrating trauma, including surgery. Other agents producing a septic arthritis include rickettsia (Rocky Mountain spotted fever, ehrlichiosis) and spirochetes (borreliosis).

Clinical signs of septic arthritis include lameness, swelling, pain of affected joint(s), and systemic signs of fever, malaise, anorexia, and stiffness. Radiography may reveal joint effusion in early cases and degenerative joint disease in chronic conditions. Arthrocentesis reveals increased WBC, especially neutrophils. The synovial fluid may be grossly purulent. Bacterial culture and antimicrobial sensitivity testing may confirm the diagnosis. Serologic testing is used for nonbacterial agents. Treatment is with appropriate IV and oral antibiotics, joint lavage, and surgical debridement in severe cases.

Old cat arthritis

Classic 'old cat arthritis' has similar causes, symptoms and treatments as for other animals and is usually an age-related degenerative condition in cats from 10 years of age due to 'wear and tear' factors.

Progressive deterioration of articular cartilage in diarthrodial joints is characterized by hyaline cartilage thinning, joint effusion, and periarticular osteophyte formation. Joint degeneration can be caused by trauma, infection, immune-mediated diseases, or developmental malformations. The inciting cause initiates chondrocyte necrosis, release of degradative enzymes, synovitis, and continued cartilage destruction and inflammation. Abnormal cartilage congruency and joint capsule anatomy can further lead to alteration in normal joint biomechanical function. Pain and lameness develop secondary to joint dysfunction or muscle atrophy and to limb disuse. Although more common in dogs, joint degeneration may also be seen in cats.

Clinical signs of degenerative joint disease include lameness, joint swelling, muscle atrophy, pericapsular fibrosis, and crepitation. Radiographic changes in the joint include joint effusion, periarticular soft-tissue swelling, osteophytosis, subchondral bone sclerosis, and possibly narrowed joint space. Arthrocentesis may be unremarkable or yield minor changes in colour, turbidity, or cell counts of synovial fluid.