Comparison of treatment of mastitis by oxytocin or antibiotics following detection according to changes in milk electrical conductivity prior to visible signs

Mastitis was induced in dairy cows by infusion of 500 cfu of Streptococcus uberis into the mammary gland. Most infections developed to clinical diseas e, and the majority were predicted by changes in the electrical conductivit y of the foremilk. The benefits of clinical prognosis and bacteriological c ure were determined for cases that were treated when predicted to develop i nto clinical mastitis and compared with cases that were allowed to develop until milk clotted or until pyrexia before intramammary antibiotic treatmen t was used. Treatment prior to clinical mastitis included use of intramamma ry antibiotic or intramuscular oxytocin to allow stripping of residual milk to remove bacteria. All infections in which treatment was delayed resulted in clinical mastitis that was cured clinically and bacteriologically by sustained treatment usi ng a broad-spectrum intramammary antibiotic preparation once daily but requ iring a mean treatment time of 10 d. It was possible to prevent clinical ma stitis from developing and to eliminate all infections in cows that were tr eated early when the developing disease was predicted by changes in the ele ctrical conductivity of quarter foremilk and was treated aggressively by ad ministering an intramammary antibiotic at each milking for 3 d. Treatment o f 20 IU of oxytocin at six successive milkings of cows that were predicted to develop disease eliminated 25% of the infections, but 75% of the cows de veloped clinical mastitis. Those cases were resolved by sustained daily tre atment using the same intramammary antibiotic. Elimination (100% clinical a nd bacteriological cure) of all infections caused by Strep. uberis was poss ible with early and aggressive or sustained use of the intramammary antibio tic. The early intervention using an intramammary antibiotic, when infectio n was first indicated by changes in the electrical conductivity of milk, wa s the most efficient method to achieve cure and led to quicker recovery of milk quality to a saleable standard.