Comparison of the effect of antibiotic dry cow teat canal and intramammary dry cow therapy of dairy cows on the prevalence of teat canal and intramammary infections at calving.

The specific therapy of bacterial colonization of the teat canals of dried-off dairy cows by means of small amounts (33 mg/0.25 ml and 14 mg/0.1 ml) of a procain benzyl penicillin-dihydrostreptomycin sulphate combination has been investigated. Of 36 teat canals treated with 0.25 ml antibiotic preparation each, 24 (66.6%) were infected at the beginning of the dry period, whereas at its termination only 7 (19.4%) showed bacteriologically positive swab cultures. By treating a further 43 quarters with 0.1 ml quantities of an antibiotic preparation each, the prevalence of infection dropped from 32.5% to 14%. Untreated controls (20 quarters) showed no significant change. Cultures of teat canal swabs were generally twice as sensitive for indicating the presence of bacteria compared to foremilk sample cultures. Staphylococcus aureus was the most commonly isolated organism, followed by Streptococcus agalactiae, Corynebacterium bovis and Staphylococcus epidermidis.