Microbiological diagnoses of chronic otitis externa in the dog.

The microbiological characteristics of otic exudates from 26 dogs with chronic otitis externa was studied with special reference to the implication of yeasts in the aetiology of the disease. A high frequency of yeasts and Staphylococcus aureus were isolated, alone or in association. In reference to the yeasts, there was a clear predominance of the genus Candida (48% of the total yeasts). Malassezia (Pytirosporum) represented only 3% of the isolates. It can be concluded that yeasts have an important role in the pathogenicity of this disease. For the microbiological diagnosis of otitis externa, we recommend the simultaneous use of Columbia/5% Sheep Blood Agar and Sabouraud-Dextrose without antibiotic addition, the use of 37 degrees C as the incubation temperature and direct microscopic observation of the sample before culture.