Diagnosis of joint disease in dogs

Arthropathies are diseases that affect joints. Arthritis is the term used to denote inflammatory changes in the joint. Arthrosis denotes noninflammatory joint disease. Polyarthritis is inflammation that simultaneously affects several joints. Osteoarthritis or osteoarthrosis is the primarily noninflammatory degenerative joint disease characterized by degeneration of articular cartilage, hypertrophy of marginal bone, and synovial membrane changes. Ankylosis is the end result of degenerative joint or inflammatory diseases, in which the joint is fused after new bone production.

Clinical presentation
The history and clinical presentations vary depending on the arthropathy. Joint disease affects dogs of all ages and sizes; cats are affected less often. Osteoarthritis, the most frequently diagnosed arthropathy, is estimated to affect as much as 20% of the canine population over 1 year of age.

Physical examination findings
Dogs show varying degrees of lameness associated with arthropathies. Muscular assymetry (between limbs) and joint enlargement may be palpable. Abnormalities in range of motion, instability, and painful response and crepitation during joint manipulations may be noted.

Radiography
Radiography is an effective and essential means of screening affected joints. The radiographic findings in affected joints range from normal to proliferative or erosive bone lesions, or they can be limited to adjacent soft tissue changes. Computed tomography often is helpful for identifying joint incongruities and fragments in osteoarthritic joints. Ultrasonography may be helpful for evaluating intra-articular and extra-articular soft tissue structures.

Laboratory findings
The synovial fluid often is evaluated to help differentiate between arthropathies. Cytologic findings range from normal to the presence of phagocytic mononuclear cells, nondegenerative neutrophils, or degenerative neutrophils and organisms. Cytologic findings may help guide the clinician to a definitive diagnosis.

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