Localized demodicosis associated with Demodex canis and Demodex cornei infestation in a dog from Mexico.

Canine demodicosis is a cutaneous parasitic disease caused by excessive proliferation of mites of the genus Demodex. This study reports a case of localized demodicosis associated with a concurrent infestation by Demodex canis and Demodex cornei in an adult mixed-breed female dog from the state of Coahuila, northern Mexico. The animal presented two focal alopecic lesions in the nasal and perioral regions, with no evidence of secondary infection. Deep skin scrapings were collected and examined by light microscopy. Species-level identification was based on diagnostic morphological characters, including opisthosomal shape and proportions, supracoxal spine morphology, and pharyngeal bulb structure, confirming the simultaneous presence of both species. This study represents the first confirmed record of D. canis and D. cornei in domestic dogs from the state of Coahuila and contributes to the knowledge of geographic distribution and diversity of demodecid mites in Mexico.