The association between the signalment, common causes of canine otitis externa and pathogens

OBJECTIVE: To determine whether associations exist between pathogens, allergies, conformational abnormalities, endocrinopathies and signalment in canine otitis externa (OE). METHODS: Medical records of 149 dogs which met predetermined inclusion criteria were evaluated retrospectively. Correlations between pathogens and the presence of allergy, endocrinopathy, conformational abnormalities and signalment were evaluated statistically. RESULTS: The shar-pei, German shepherd and cocker spaniel breeds were over-represented compared with the hospital's breed distribution (P<0·001). German shepherd dogs and cocker spaniels were statistically more prone to infection with rod-shaped organisms and Labrador retrievers less than other breeds (P=0·034). Almost all dogs that were older than five years when diagnosed with OE had cocci (P=0·01) and also had higher levels of rods (P=0·028). The incidence of rods was higher in endocrinopathies (P=0·004), while that of Malassezia spp. tended to be higher in allergies (P=0·098). There were no statistically significant differences among the groups for all the other parameters examined. CLINICAL SIGNIFICANCE: OE infection is usually not influenced by primary causes or predisposing factors. Endocrinopathies may be followed by a more severe otitis, however. OE may be more severe when it affects older dogs.