Joint Disease

56 Joint Disease



Astrid Nielssen



1. What categories of disease can affect joints?

Diseases of the muscles, tendons, or ligaments associated with a joint; articular fractures; developmental and congenital disorders (e.g., osteochondrosis desiccans, hip dysplasia); metabolic, dietary, and endocrine abnormalities; neoplasia (e.g., synovial cell sarcoma); and various arthritides can all be associated with joint dysfunction and disease.


2. What are the definitions of arthropathy and arthritis?

An arthropathy is any disease affecting a joint. An arthropathy can affect a single joint (monoarticular arthropathy or monoarthropathy) or many joints (polyarticular arthropathy or polyarthropathy). Arthritis is defined as any condition causing inflammation within a joint. Arthritis can also be described as affecting one (mono) or multiple (poly) joints.


3. How can arthritis be classified?

Arthritis can generally be classified as either primarily inflammatory or noninflammatory in nature. Systemic signs of illness can be seen in association with inflammatory joint diseases and can include fever and lethargy. Inflammatory joint diseases can be either infectious or immune-mediated and are characterized by inflammatory changes within the synovium and synovial fluid. Immune-mediated joint diseases are typically further categorized, based on radiographic findings, as either erosive or nonerosive. Although commonly referred to as arthritis, degenerative joint disease is noninflammatory. It is associated with degenerative changes in the joint cartilage, absence of inflammation in the synovium or synovial fluid, and absence of systemic signs of illness.


4. What are some of the possible causes of infectious polyarthritis?

Numerous agents have been identified as causing arthritis in the dog, including fungi, bacteria (including Borrelia burgdorferi and bacteremic conditions such as those associated with endocarditis and discospondylitis), bacterial L-forms, rickettsial infections (Ehrlichia spp., Rickettsia rickettsii), mycoplasma, protozoal agents, and viruses. Although a polyarthropathy is most commonly identified in association with these infections, a septic monoarthropathy in the dog may be seen in association with direct organism inoculation into the joint, resulting from trauma or other such insult. Identification of these various agents depends on obtaining a complete clinical and medical history, thorough physical examination, and appropriate diagnostic imaging and laboratory investigations (including cytologic assessments, serologic testing, and cultures).


5. What is erosive polyarthritis?

The most common form of erosive polyarthritis in the dog is canine rheumatoid arthritis (RA). It is a rare condition seen most commonly in young to middle-aged small-breed dogs. Like all of the immune-mediated arthropathies, the most distal joints are typically affected first and most severely. Lameness, joint swelling, and systemic symptoms such as fever, lethargy, and inappetance can be seen. With time, significant joint deformity can arise in affected dogs. The cause of RA is unknown, although autoimmune and immune-mediated processes are known to be involved. Antiglobulin antibodies (referred to as rheumatoid factor) are involved. The role of immune system changes associated with a response to chronic antigenic stimulation, such as with canine distemper virus infection, is still speculative at this time.


Other forms of erosive polyarthritis that do not fit into the definition of RA have also been identified in the dog. An erosive polyarthropathy in Greyhounds has been identified. It is associated with typical symptoms of RA but also with low to negative rheumatoid factor and antinuclear antibody titer levels.

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Jul 31, 2016 | Posted by in INTERNAL MEDICINE | Comments Off on Joint Disease

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