Malignant Mesothelioma of Tunica Vaginalis in a Dog

Abstract

Orchidectomy was performed on a 10-year-old Shetland sheepdog with a mass in a swollen and suppuratively necrotized left scrotum after infection control. The mass had invaded the peritoneal cavity through the inguinal canal, and asctites was found in the scrotum. Swelling of the bilateral inguinal lymph nodes suggested metastasis. We performed orchidectomy, excision of both inguinal lymph nodes, and partial excision of the greater omentum. Pathologically, the tumor was diagnosed as malignant mesothelioma of the tunica vaginalis testis with lymphogeneous metastasis. The pet owner declined further treatment such as chemotherapy, and the dog died at home on the 43 rd day, i.e., 32 days after surgery. Mesothelioma of the tunica vaginalis testis is rare in dogs, and this report is only the second in Japan.