During the last years, the interest of keeping dogs as pets, for hunting or as guards is continuously increasing. The owners are more and more concerned about their health. The inflammation of external ear canal induced by foreign bodies, microbial or parasitic agents is not a life-threatening condition, but causes discomfort in the dog and worries the owners. Very often, the untimely, improper treatment or the use of inappropriate drugs results in chronicisation of the disease and delays the complete healing of the patient. In most cases of external otitis, veterinarians apply antibacterial medications without laboratory examinations – isolation, identification of the etiological agents and testing of their sensitivity to chemotherapeutics. The treatment of otitis in dogs could be inefficient, if the possible involvement of yeasts is not taken into consideration. This information focused our attention to investigating the frequency of isolation of M. pachydermatis and its role in the etiology and the clinical manifestation of external otitis in dogs, and laboratory diagnosis, with regard to the optimization of therapeutic approaches.