PolyMast Intramammary Infusion 12ct. - Prescription RequiredPoly Mast Intramammary Infusion 10 mL 12ct PolyMast (hetacillin potassium) for Intramammary Infusion is indicated for the treatment of acute, chronic or subclinical bovine mastitis and should be used at the first signs of inflammation or at the first indication of any alteration in the milk. Subclinical infections should be treated immediately upon determining, by CMT or other tests, that the leukocyte count is elevated, or that susceptible pathogen