Erosive, Immune-Mediated Polyarthritis in Dogs Erosive, immune-
mediated polyarthritis is an immune-mediated inflammatory
disease of the joints, in which the cartilage of the dog's joint
(articular cartilage) is eroded away. In this disease, cell-
mediated immunity is thought to attack articular cartilage. The
suspected causes for this are T lymphocyte effector cells that
carry out the attack response, and an abnormal antigenic
response to the host antibody. That is, an immune response to a
substance that stimulates production of antibodies, an antigen,
which acts as a “trigger”. In effect, the body is fighting
against itself. Leukocyte cells (white blood cells), leukocyte
enzymes (catalyzing reactions), cell-mediated immunity, immune
complexes (an antibody bound to its triggering antigen), and
autoallergic reactions are all directed against cartilage
components. This leads to an inflammatory response by the tissue
surrounding the cartilage, and complement protein activation in
response to the immunity displayi