Localized Demodicosis in a Dog After Fluticasone Propionate Treatment for Chronic Bronchitis

An 11-year-old, castrated male Shetland Sheepdog presented for a 3-week history of localized nonpruritic alopecia and scaling affecting the peri-nasal region. The dog was being managed for several comorbidities, including chronic bronchitis successfully controlled with the chronic administration of inhaled fluticasone propionate. The physical examination was unremarkable aside from erythema, symmetrical alopecia, scaling and follicular casts affecting the peri-nasal region. Deep skin scrapings and histopathological examination from the lesional skin revealed several live demodex mites consistent with Demodex canis. Transcriptome analysis of lesional skin demonstrated significant downregulation of several cytokines involved in the T helper (Th) 2 and Th17 pathway with moderate upregulation of Th1 cytokine IFN-γ and T-cell recruitment chemokine CXCL10. The dog was immediately treated with oral fluralaner. Clinical signs of demodicosis resolved after 8 weeks and a trichogram was negative for live and/or dead demodex mites. The dog has remained on twice-daily administration of inhaled fluticasone and oral fluralaner every 3 months for 15 months without a demodicosis relapse, in addition to medication to manage the dog's comorbidities. To the author's knowledge, this is the first case of localized demodicosis caused by an inhaled glucocorticoid in a dog.