Breed variations in histopathologic features of chronic severe otitis externa in dogs: 80 cases (1995-2001).
OBJECTIVE
To compare pathologic changes of the horizontal ear canal associated with chronic severe otitis externa between Cocker Spaniels and dogs of other breeds.


METHODS
Retrospective study.


METHODS
80 dogs with severe otitis externa that required total ear canal ablation with lateral bulla osteotomy.


METHODS
Medical records were reviewed for breed, sex, and age at time of surgery. Histologic specimens from the horizontal ear canal were evaluated by a single examiner for overall tissue response pattern and scored for sebaceous gland hyperplasia, ceruminous gland hyperplasia, ceruminous gland ectasia, fibrosis, pigment-laden macrophages, and osseous metaplasia.


RESULTS
48 of 80 (60%) dogs were Cocker Spaniels. Thirty-five of 48 (72.9%) Cocker Spaniels had a predominately ceruminous tissue response pattern; only 9 of 32 (28.1 %) dogs of other breeds had the same pattern. Other breeds most commonly had a pattern dominated by fibrosis (n = 13 [40.6%]); fibrosis was the predominant pattern in only 4 of 48 (8.3%) Cocker Spaniels. Discriminant analysis and K-means clustering of 4 histopathologic criteria correctly classified 75% of the dogs as Cocker Spaniels or all other breeds.


CONCLUSIONS
Cocker Spaniels are at increased risk for chronic severe otitis externa requiring total ear canal ablation with lateral bulla osteotomy, indicating that earlier and more aggressive management of the primary otitis externa and secondary inflammation is warranted in this breed. Cocker Spaniels with chronic severe otitis externa have distinct differences in pathologic characteristics of the horizontal ear canal, compared with other breeds.
D000818:Animals; D001947:Breeding; D002908:Chronic Disease; D016000:Cluster Analysis; D016002:Discriminant Analysis; D004283:Dog Diseases / Q000235:genetics* / Q000473:pathology* / Q000601:surgery; D004285:Dogs; D004424:Ear Canal / Q000033:anatomy & histology*; D005260:Female; D020022:Genetic Predisposition to Disease; D008297:Male; D010027:Osteotomy / Q000662:veterinary; D010032:Otitis Externa / Q000235:genetics / Q000473:pathology / Q000601:surgery / Q000662:veterinary*; D012189:Retrospective Studies; D016896:Treatment Outcome