The invention discloses a mammalian teat dip for controlling mastitis, a method for preparing the composition and a method of treatment of mammals. The composition contains a film-forming polymer blend and at least one antimicrobial. The polymer blend contains a solvent-soluble, thermoplastic polyurethane and a hydrophilic poly(N-vinyl lactam). Upon application to mammalian skin, this composition leaves a long-lasting, water-resistant, residual, elastic film which treats and protects mammalian skin from infection.