Demodex cati infestation in association with feline cutaneous squamous cell carcinoma in situ: a report of five cases

Demodex cati infestation was identified at lesional sites of multicentric s quamous cell carcinoma in situ (Bowen's disease) in five elderly domestic s horthaired cats. Lesions were observed on the face, neck, shoulders, stifle s and limbs. Deep skin scrapings taken from lesional skin contained D. cati eggs, larvae and adults in four cases. D. cati were discovered histologica lly in four cases. Histopathology of skin biopsy specimens confirmed the di agnosis of squamous cell carcinoma in situ in all cases. Serology for felin e immunodeficiency virus (FIV) was positive in three cats. Remission of Bow en's disease lesions was obtained in 4-6 months using oral retinoids etreti nate (one case) or acitretin (one case). It is suspected that local immunod eficiency due to epithelial dysplasia might have predisposed the skin to a focal multiplication of D. cati. Alternatively, FIV infection may have led to immune suppression predisposing the cats to both papillomavirus-induced epithelial dysplasia and D. cati infestation.