To treat existing mastitis infections and to provide protection against further infections during the dry period.

Orbenin is active against Gram-positive organisms associated with mastitis. It is effective against Streptococcus agalactiae and other streptococcal species, penicillin-resistant and sensitive staphylococci and Actinomyces pyogenes. Orbenin is not destroyed by staphylococcal penicillinase. It is therefore active against penicillin-resistant staphylococci which are an important cause of mastitis.