Comparison of antibiotic administration in conjunction with supportive measures versus supportive measures alone for treatment of dairy cows with clinical mastitis

摘要

A herd of 260 lactating cows at the University of Illinois Dairy Research Farm was monitored for signs of clinical mastitis between January 1994 and January 1996. Cows were examined at the onset of clinical mastitis, assigned a severity score, and randomly assigned to receive antibiotic (intramammary administration of cephapirin, i.v. administration of oxytetracycline, or both) and supportive treatment (administration of oxytocin, stripping of affected glands, and, in severely affected cows, administration of flunixin meglumine or fluids) or supportive treatment alone. Treatment was continued until 24 h after signs of clinical mastitis resolved (clinical cure). Milk samples from affected glands were submitted for bacterial culture before initial treatment and every 2 weeks thereafter until the causative organism was no longer isolated (bacteriological cure). During the study, 124 cows had 172 clinical mastitis periods involving 206 glands. When mastitis was caused by Streptococcus spp. or coliform bacteria (Escherichia coli, Klebsiella spp., Citrobacter spp., Enterobacter spp.), clinical cure rate by the tenth milking was significantly higher if antibiotics were used. Bacteriological cure rate at 14 days was significantly higher when antibioticswere used, particularly if mastitis was caused by Streptococcus spp. Cows receiving antibiotics developed fewer subsequent episodes of clinical mastitis during the 60 days after the initial episode of mastitis and had less severe clinical disease than cows that did not. It is concluded that, in herds in which mastitis is often caused by environmental bacteria, antibiotic and supportive treatment may result in a better outcome for cows with clinical mastitis than supportive treatment alone.