Comparison of penicillin, oxytetracycline, and trimethoprim-sulfadoxine in the treatment of acute undifferentiated bovine respiratory disease.

Penicillin, oxytetracycline, and a trimethoprimsulfadoxine combination were compared as first choice antibiotics for the treatment of acute bovine respiratory disease in weaned beef calves. There was no statistical difference in the mortality losses due to respiratory disease; however, the case fatality rate in the trimethoprim-sulfadoxine treatment group (3%) was markedly lower than in the penicillin (10%) and oxytetracycline (8%) treatment groups. The trimethoprim-sulfadoxine group also had statistically fewer treatment days compared to the penicillin and oxytetracycline groups (p < 0.05). Inclusion of mortality costs in the calculation of treatment costs demonstrated that treatment of the trimethoprimsulfadoxine group was appreciably less costly than treatment of the other groups. Temperature response abnormalities, defined as either an elevation in temperature or a failure of temperature to drop from one treatment day to the next, were associated with a relapse rate of approximately 50%. In vitro antibiotic sensitivity testing of Pasteurella haemolytica isolated from pretreatment nasal swabs was not a useful predictor of treatment success of antimicrobials.