Clinical and histological aspects of localized and generalized canine demodicosis

Demodicosis is a skin condition caused by Demodex mite, frequently diagnosed in clinical routine. The purpose of this study was to compare the clinical and histological manifestations of localized and generalized demodicosis in dogs, relating the amount of mites and microscopic lesions. The study group was formed by 46 dogs, 28 with generalized demodicosis, and 18 with the localized form of the disease, all of them with positive skin scrapings. Macroscopic lesions data in dermatological form were noted, and skin samples were collected for microscopic study. The histopathological analysis was individually performed by three reviewers without intercommunication, being considered the result that more occurred. Alopecia, scaling, erythema, and crusting were the most common clinical lesions in both forms of the disease. Histological severe dermatitis occurred especially in dogs with localized and generalized disease that had concomitant pyoderma and Demodex sp. mites were visualized with intensity moderate and severe in the most dogs with both forms of the diseases. Perifolliculitis was the most evident microscopic follicular change in this study, followed by folliculitis and furunculosis wall, which had higher relative occurrence in dogs with localized demodicosis. According to the results obtained, the severity of histologic lesions does not necessarily correspond to the clinical presentation of the disease, in addition to the amount of mites that apparently is not indicative of localized or generalized clinical lesions, and cannot differentiate clinical disease by histopathology.