(Merial) Zactran contains gamithromycin, a macrolide sub-class antimicrobial. For treatment of bovine respiratory disease (BRD) associated with Mannheimia haemolytica, Pasteurella multocida, Histophilus somni and Mycoplasma bovis, and for control of BRD associated with Mannheimia haemolytica and Pasteurella multocida in beef and non-lactating dairy cattle. A single dose of Zactran provides up to 10 days BRD treatment and control. Administer one dose, 2 ml per 110 lbs. SQ in the neck, not to exceed 10 ml per injection site. Zactran is not for use in female dairy cattle 20 months of age or older, or in calves to be processed for veal. Gamithromycin 150 mg/ml.