Unusual presentation of crusted Norwegian scabies in a cat successfully treated with an oral isoxazoline

Abstract

An 8-year-old male neutered domestic shorthaired cat was presented with three-month progressive dermatitis associated with pruritus and crusted lesions resembling cutaneous horns on all 4 paw pads. Firm crusted lesions extended up to 10 mm in some areas. Skin scraping revealed large numbers of mites and eggs compatible with Sarcoptes scabiei. A 4-mm skin biopsy showed marked diffuse ortho- and para-keratosis with intracorneal arthropods, bacterial cocci, acanthosis, and minimal perivascular mastocytic and suppurative dermatitis. The cat was treated with a single oral dose of afoxolaner combined with milbemycin oxime. Complete resolution of the clinical signs was observed on the second visit 14 days later. This unusual presentation resembled Norwegian scabiosis in humans.