Immunopathogenesis of canine aural haematoma

Abstract

Data are presented from 15 dogs with aural haematoma. The series included six Labrador retrievers and four golden retrlevers and the mean age was 8.0 ± 3.02 years. Five dogs had evidence of pruritic skin disease and five further cases had other concurrent disease. Haematoiogy and serum biochemistry were normal in 12 and 13 of the 15 dogs, respectively. Ail dogs were Coombs' negative and serum antinuclear antibody had negative or low titres in ail the 11 cases tested. Histopathological examination of biopsies from the affected ears revealed variable degrees of erosion of auricular cartilage with fibrovascular granulation tissue filling the cartilage defects. There was minimal perichondrai inflammation. The biopsies were studied by immunohistochemlstry for deposition of lmmunoglobulln G (IgG), immunogiobulln M (IgM) and complement C3. In one dog there was basement membrane zone deposition of IgG and in another there was focal interepithellai deposition of both igG and IgM. The findings of this study do not support an autoimmune pathogenesis for canine aural haematoma, but suggest that an early immunological event may underlie the observed cartilage erosion.