Red fox with sarcoptic mange

Animals infected with Sarcoptes mites develop erythematous macules and crusts on the skin. Immunosuppressed animals may develop massive infections with alopecia, lichenification, and accumulation of thick scales and fissuring of the skin. Histologically, the mites can be seen within the parakeratotic stratum corneum. The adult mites have striations on their cuticles and large dorsal cuticular spines; Sarcoptes is the only mite with these prominent dorsal spines. There is epidermal hyperplasia and an overlying thick crust composed of orthokeratotic and parakeratotic debris, serum, and viable and degenerate neutrophils. Dermal vessels are dilated and lined by hypertrophic endothelium. There is often a perivascular infiltrate of lymphocytes and eosinophils. Chronic lesions have dermal fibrosis and a predominantly mononuclear inflammatory response.
http://www.afip.org/vetpath/WSC/WSC95/95wsc18.htm