Quantity and distribution of Malassezia organisms on the skin of clinically normal dogs.

OBJECTIVE: To define the extent to which Malassezia organisms can be recovered from the skin of clinically normal dogs and to assess differences in organism recovery related to anatomic sampling site and to method of collection.
DESIGN: Prospective, controlled study. ANIMALS: 19 clinically normal dogs. PROCEDURE: The number of Malassezia pachydermatis organisms were determined in fungal cultures of samples obtained from the skin of clinically normal dogs, using an adhesive tape method to obtain samples from 10 sites/dog. Additionally, 3 methods (direct impression, swabbing technique, and superficial skin scraping) that are commonly used for obtaining samples for cytologic examination were evaluated.
RESULTS: Malassezia organisms were found in low numbers as part of the microflora of the skin of clinically normal dogs. Number of organisms differed significantly for various anatomic locations (chin, highest number; inguinal and axillary regions, lowest number). Malassezia organisms were identified more frequently by use of adhesive tape and fungal culturing than by the methods used for cytologic examination. However, comparing methods used for obtaining samples for cytologic examination with each other, marked differences were not detected in our ability to recover yeast organisms among the 3 techniques. CLINICAL IMPLICATIONS: Although Malassezia spp is part of the microflora of the skin of clinically normal dogs, it is extremely difficult to detect the organism by any of the 3 sampling methods used for sample collection for cytologic examination. Therefore, anatomic site and method of sample collection should be considered when attempting to make a diagnosis of Malassezia dermatitis.