A clinical and immunopathological study of Brucella abortus strain 19--induced arthritis in cattle.

From a series of 11 calves presenting with a clinical unilateral gonitis (inflammation of the stifle), six were subjected to serological examination for titres against Brucella abortus and to subsequent post mortem examination. Tissues from five calves studied showed similar clinical and radiological features with post mortem examination confirming the presence of characteristic arthritic lesions in the affected stifle and other joints. The immune studies indicated the presence of B abortus strain 19 antigenic material within the cells of the stifle, synovial membrane and the drainage lymph nodes. Attention is drawn to the apparent absence of intact brucella organisms and to the incompatibility between some of the serum agglutination titres and the results of the immune studies. It is concluded that the absence of an elevated serum agglutination titre to B abortus is not an indication of the absence of B abortus antigenic material and that B abortus strain 19 under certain circumstances is pathogenic to calves causing a characteristic and serious clinical syndrome.