These lesions are the result of ascending bacterial infections. Various bacteria, including Eubacterium (Corynebacterium) suis and coliforms, have been isolated from the lesions. These lesions usually occur in older sows and are a common cause of sporadic deaths. Death often occurs during or shortly after advanced pregnancy, a time of maximum stress on kidney function. Anything that interferes with adequate water intake or urination may predispose to infection. Eubacterium suis is present in the preputial diverticulum of most boars. The organisms may be transmitted to the sow during copulation. Many sows with cystitis/nephritis have hematuria, the first sign of infection, within three weeks of breeding. This is followed by progressive loss of body weight. The lesions are uncommon in boars.