Effect of sulfadimethoxine-ormetoprim in the treatment of calves with induced Pasteurella pneumonia.

The efficacy of sulfadimethoxine (SDM)-ormetoprim (OMP) was evaluated in calves with induced Pasteurella pneumonia. A dose-titration study comparing 3 doses of SDM-OMP was performed to determine the optimal dose. Treatments included: group 1--nontreated controls; group 2--33 mg of SDM-OMP/kg of body weight, orally on day 1 and 17 mg/kg on days 2 to 5; group 3--66 mg of SDM-OMP/kg, orally on day 1 and 33 mg/kg on days 2 to 5; group 4--99 mg of SDM-OMP/kg, orally on day 1 and 50 mg/kg on days 2 to 5; and group 5--11 mg of oxytetracycline/kg, IV daily for 4 days. Group-2 calves responded to treatment as well as did group-5 calves. Group-4 calves responded the same as did group-3 calves. However, group-2 calves did not respond as well as did groups 3, 4, and 5 calves.