IMMUNOPATHOGENESIS OF CANINE AURAL HEMATOMA

Data are presented from 15 dogs with aural haematoma, The series inclu ded six Labrador retrievers and four golden retrievers and the mean ag e was 8.0 +/- 3.02 years. Five dogs had evidence of pruritic skin dise ase and five further cases had other concurrent disease, Haematology a nd serum biochemistry were normal in 12 and 13 of the 15 dogs, respect ively, All dogs were Coombs' negative and serum antinuclear antibody h ad negative or low titres in all the 11 cases tested. Histopathologica l examination of biopsies from the affected ears revealed variable deg rees of erosion of auricular cartilage with fibrovascular granulation tissue filling the cartilage defects, There was minimal perichondral i nflammation. The biopsies were studied by immunohistochemistry for dep osition of immunoglobulin G (IgG), immunoglobulin M (IgM) and compleme nt C3. In one dog there was basement membrane zone deposition of IgG a nd in another there was focal interepithelial deposition of both IgG a nd IgM, The findings of this study do not support an autoimmune pathog enesis for canine aural haematoma, but suggest that an early immunolog ical event may underlie the observed cartilage erosion.