mastitis, bovine, bacterial inflammation of the udder in dairy cattle. It is spread during the process of milking, either by machine or by hand, and by flies. The symptoms include inflammation of the udder and clotted, bloody milk. If gangrene develops, death can result. Control of the disease requires sanitary facilities, proper milking procedures, and the segregation of affected animals. The disease is now treated by penicillin in combination with a sulfa drug and other antibiotics.