Epidemiological and Etiological Studies on 59 Aural Hematomas of 49 Dogs

Abstract

Fifty-nine cases of aural hematoma occurring in 49 dogs were reviewed. The number of affected dogs weighing less than 5 kg, 5 to 10 kg, 10 to 20 kg, and more than 20 kg, was 1 (2.1%), 6 (12.8%), 11 (23.4%), and 29 (61.7%), respectively. Golden Retrievers and Labrador Retrievers occupied 55.1% of all the dogs, suggesting the higher risk of these breeds. Of all 59 hematomas, 45 (76.3%) accompanied with otitis externa and 52 (88.1%) occurred at more than 5-year-old. Histopathological examinations of the pinna surrounding hematoma revealed partial erosions of auricular cartilage in all 4 cases examined. These results suggest that there are several risk factors for aural hematoma including larger-breed dogs (Golden Retrievers and Labrador Retrievers), middle-aged to older dogs, and concurrent otitis externa. In addition, age-related alternation of the auricular cartilage, and self-trauma, may contribute to the occurrence of cartilage fracture resulting in hematoma formation.