Comedones and epidermal cysts on the abdominal skin of a dog occurring after a laparotomy.

An 8-year-old neutered male shih tzu dog underwent laparotomy for cystolithectomy. Ten days later, multiple various-sized cystic nodules were observed on the suture line and surrounding abdominal skin, although the surgical incision had healed well. Microscopically, various-sized cysts lined with thin walls of stratified squamous epithelium in the dermis were dilated and filled with keratin. Adnexal differentiation from the wall was not seen. Thus, the abdominal lesions were diagnosed as comedones and epidermal cysts. Herein, we describe the case of a dog with comedones and epidermal cysts on the abdominal skin after a laparotomy. Key clinical message: Multiple various-sized cystic lesions of the follicles are described. The implantation of epidermal fragments into the dermis by surgery may induce epidermal cysts and comedones in the skin of hyperadrenocorticism-affected dogs.