COMPARISON OF ANTIBIOTIC ADMINISTRATION IN CONJUNCTION WITH SUPPORTIVE MEASURES VERSUS SUPPORTIVE MEASURES ALONE FOR TREATMENT OF DAIRY-COWS WITH CLINICAL MASTITIS

Objective-To determine whether antibiotic and supportive treatment wou ld improve outcome for dairy cows with naturally developing clinical m astitis, compared with supportive treatment alone. Design-Randomized c ontrolled trial. Animals-124 cows in one herd with 172 episodes of cli nical mastitis. Procedure-Cows were examined at the onset of clinical mastitis, assigned a severity score, and randomly assigned to receive antibiotic (intramammary administration of cephapirin, IV administrati on of oxytetracycline, or both) and supportive treatment (administrati on of oxytocin, stripping of affected glands, and, in severely affecte d cows, administration of flunixin meglumine or fluids) or supportive treatment alone. Treatment was continued until 24 hours after signs of clinical mastitis resolved (clinical cure). Milk samples from affecte d glands were submitted for bacterial culture before initial treatment and every 2 weeks thereafter until the causative organism was no long er isolated (bacteriologic cure). Results-When mastitis was caused by Streptococcus spp or coliform bacteria, clinical cure rate by the tent h milking was significantly higher if antibiotics were used. Bacteriol ogic cure rate at 14 days was significantly higher when antibiotics we re used, particularly if mastitis was caused by Streptococcus spp. Cow s receiving antibiotics developed fewer subsequent episodes of clinica l mastitis during the 60 days after the initial episode of mastitis an d had less severe clinical disease than cows that did not. Clinical im plications-Results suggest that, in herds in which mastitis is often c aused by environmental bacteria, antibiotic and supportive treatment m ay result in a better outcome for cows with clinical mastitis than sup portive treatment alone.