Antibodies to canine collagen types I and II in dogs with spontaneous cruciate ligament rupture and osteoarthritis.

Antibodies to homologous collagens, types I and II, have been found in the sera and synovial fluids of dogs with spontaneous cruciate ligament rupture and osteoarthritis. Samples from 30 dogs with degenerative joint disease of the knee and from 15 healthy dogs were investigated by enzyme-linked immunosorbent assay. Fifty-three percent of dogs with joint disease showed significant levels of anti-type I collagen antibodies in their sera, and 56% had anti-type II reactivity. Ninety-one percent of the dogs with joint disease exhibited antibody reactivity to type I collagen in their synovial fluid, and 88% showed reactivity to type II collagen. Correlation of these results with the clinical data indicated that the antibodies had been elicited by antigens derived from cruciate ligaments (type I collagen) and from altered joint cartilage (type II collagen). Immunologic reactivity in this form of canine osteoarthritis is a new concept, and it should be considered in our attempts to understand the pathogenesis of this disease.