Canine Immune-Mediated Joint Disease Study Guide

Overview and Clinical Importance

Immune-mediated joint disease (IMJD) encompasses a group of inflammatory joint conditions where the immune system attacks the synovial membranes, resulting in sterile synovitis. Immune-mediated polyarthritis (IMPA) is the most common cause of polyarticular disease in dogs and represents the most frequent cause of fever of unknown origin in canines. Understanding the classification, diagnosis, and treatment of these conditions is essential for NAVLE success and clinical practice.

IMPA is characterized by chronic synovial inflammation in two or more joints, failure to isolate an organism from joint fluid, and a positive response to immunosuppressive therapy. The underlying pathology typically involves a type III hypersensitivity reaction where immune complexes deposit in the synovial basement membrane, triggering complement activation and neutrophil recruitment.

Classification of Immune-Mediated Joint Disease

Immune-mediated joint diseases are classified based on radiographic findings (erosive vs. non-erosive) and presence or absence of underlying disease triggers (primary vs. secondary).