Nocardia mastitis in cattle. 1. Clinical observations and diagnosis in 7 particular cases

Lately reports of nocardial mastitis have been increasing. Therefore the clinical aspects of 7 individual cases were investigated. Pathologic-anatomical changes of the udder were registered and bacteriological examination of tissue and milk probes were performed. All of the cows had a mastitis during previous lactation periods which had to be treated with antibiotics. The infected quarters recovered in no cases. Shortly after parturition 6 cows had a severe acute mastitis. The cows were treated intramammarily and parenterally with various antibiotics during several days. The infected quarter became indurated and strongly enlarged. These changes were not influenced by therapy, and the cows lost weight. 14 days after the outbreak of the illness, all 6 cows were culled. One cow had a chronic Nocardia mastitis with involution of the affected quarter. Though treated several times, this cow did not recover either. The histopathological examination of the affected quarters revealed an acute to chronic, necrotic to granulomatous mastitis. Nocardia asteroides was histologically and bacteriologically proven to be the causative agent. The reason for the frequent infections with Nocardia and the way of infection is not clear yet. Therapy with antibiotics brought no recovery in any cases. The infected cows should be removed from the herd or culled.