Chanamast DC Uses For routine use in cows at drying off, to treat existing intramammary infections and to assist in preventing new infections occurring during the dry period. Chanamast DC contains cloxacillin which is active against the following major pathogens associated with mastitis Penicillin resistant and sensitive Staphylococcus aureus, Streptococcus spp including S. agalactiae and S. uberis and Actinomyces pyogenes.