) Myco Silencer Once is an aid in the prevention of pneumonia caused by Mycoplasma hyopneumoniae. Administer a single 2 ml dose IM at 3 weeks of age or older. Vaccination with a single dose of Myco Silencer Once has shown to be protective for up to 6 months. Alternatively, for herds requiring a 2-dose program (extreme stress or disease challenge) give a 1 ml dose at 3 weeks of age or older, followed by a second 1 ml dose 2-3 weeks later. Myco Silencer Once contains an inactivated culture in Microsol Diluvac Forte adjuvant.