This case report describes a highly pruritic, papular and crusted dermatitis affecting the dorsum of a dog and microscopically diagnosed as dermatitis induced by Straelensia cynotis. Histologically, each papule was characterized by a dilated hair follicle with marked pseudoepitheliomatous hyperplasia, perifollicular mucinosis and an abundant mononuclear infiltration by plasma and mast cells. Each dilated follicle contained a larval mite. A therapy including systemic ivermectins and oral antibiotic therapy was initiated, but the clinical response was poor. To the best of the authors' knowledge, this is the first report of straelensiosis in Portugal, and the second in Europe.