Boehringer Ingelheim Animal Health has announced a change to the datasheet for Mamyzin, its antibiotic treatment for bovine mastitis.

The milk withdrawal has been reduced from 108 hours to 96 hours and the dose is now 15 mg/kg for three consecutive days.

Kath Aplin, veterinary adviser for Boehringer Ingelheim Animal Health, said: "The new dosage regimen gives clearer guidance to vets and their clients; a 660kg cow should receive 10g of penethamate hydriodide (one vial) daily for three days.

Mamyzin, a lecithin coated pro-drug of benzyl penicillin, is highly lipophilic and actively concentrates in the udder, where it is capable of entering epithelial cells to achieve intracellular bacterial kill1. It provides targeted, narrow spectrum treatment for gram positive mastitis in situations where injectable therapy for mastitis is required."


  1. Almeida RA et al (2007) Intracellular killing of mastitis pathogens by penethamate hydriodide following internalization into mammary epithelial cells. J Vet Pharmacol Ther30:151–156.