THE EFFECTS OF EARLY ANTIBIOTIC-TREATMENT FOLLOWING DIAGNOSIS OF MASTITIS DETECTED BY A CHANGE IN THE ELECTRICAL-CONDUCTIVITY OF MILK

Mastitis was induced experimentally by infusion of Streptococcus uberi s or Staphylococcus aureus into the mammary glands of lactating dairy cows. Clinical mastitis was identified when clots appeared in foremilk (conventional diagnosis) or was predicted by changes in the electrica l conductivity of foremilk (early diagnosis). The responses to intrama mmary antibiotic treatment that was initiated after early diagnosis of mastitis and after conventional diagnosis were compared. Early treatm ent significantly limited the severity of the disease and, in many cas es, prevented the appearance of any visible signs of infection. Milk y ield was less depressed, and the somatic cell count (SCC) was lower, w hen treatment was initiated earlier. The SCC of the quarter at the tim e mastitis was predicted was approximately 2 x 10(6) cells/ml for both pathogens, which was significantly less than when clots appeared at c onventional diagnosis, approximately 4 x 10(6) and 12 x 10(6) cells/ml for Staph. aureus and Strep. uberis, respectively. The time required for SCC to recover to <4 x 10(5) cells/ml was significantly less, appr oximately half, for both pathogens following early detection and early initiation of treatment. When treatment was administered in response to early detection, the bacteriological and clinical cure was almost c omplete, and the amount of antibiotic used was less than or equal to 5 0% less. Obvious benefits for milk yield and quality and the health of the cow would result when changes in the electrical conductivity of m ilk are used to predict clinical mastitis and when treatment is initia ted early.