IMMUNOHISTOCHEMICAL EVIDENCE FOR IMMUNOGLOBULIN AND COMPLEMENT DEPOSITION IN SPINAL-CORD LESIONS IN DEGENERATIVE MYELOPATHY IN GERMAN-SHEPHERD DOGS

The purpose of this study was to examine the distribution of immunoglo bulin and complement component C3 in spinal cord tissues of dogs with degenerative myelopathy. Sections of formalin-fixed paraffin-embedded spinal cord from five German Shepherd dogs with clinical and histologi cal features consistent with degenerative myelopathy (DM) and one norm al dog were tested immunohistochemically for deposition of immunoglobu lin G (IgG) and the third component of complement (C3). In all dogs th ere was staining associated with large and small blood vessels. In add ition, in the dogs with DM there was focal staining for IgG and C3 in spinal nerve tracts characteristically affected in DM. Deposition of I gG and C3 was found in histological lesions, and in addition, in other areas independent of visible lesions, suggesting that IgG and C3 depo sition may precede histological evidence of spinal cord damage. These findings suggest a role for immune-mediated destruction of the spinal cord which may contribute to the pathogenesis of DM in German Shepherd dogs.