Bovine gangrenous mastitis is an acute or peracute condition involving one or more quarters of the cow's udder. It occurs infrequently, but when it occurs, mortality of the affected cows is high. A partial mastectomy of one quarter using a cranial epidural analgesia with 2% lignocaine is described to manage a gangrenous mastitis affecting only one quarter caused by Proteus mirabilis (a gram-negative bacteria) which was not amenable to medical treatment. Partial mastectomy can be a safe and effective procedure for ruminants with udder disease in genetically or otherwise valuable cattle.