Assessment of the efficacy of tilmicosin as a treatment for Mycoplasma gallisepticum infections in chickens.

This study involved two experiments which examined the efficacy of 'in water' tilmicosin medication for the treatment of experimental Mycoplasma gallisepticum (MG) disease. The first experiment investigated tilmicosin concentrations of 50, 100, 200 and 400 mg/l administered for 5 days. In the second experiment, dose levels of 50, 75 and 100 mg/l tilmicosin administered for either 3 or 5 days were investigated. The first experiment suggested that tilmicosin was effective in reducing the incidence and severity of airsacculitis lesions caused by MG. In the second experiment tilmicosin treatment was found to significantly reduce the severity of airsacculitis caused by MG, although there was no effect on the morbidity. These experiments suggest that tilmicosin is effective in the treatment of MG infections when administered in drinking water. The minimum effective concentration of tilmicosin in drinking water appears to be at or less than 50 mg/1 when administered for either 3 or 5 days.