Treatment efficacy of tildipirosin or tulathromycin for first treatment of naturally occurring bovine respiratory disease in a commercial feedlot

Abstract

Tildipirosin was compared to tulathromycin for treatment of bovine respiratory disease (BRD) in feedlot cattle. Six hundred calves identified with BRD by feedlot pen riders with a rectal temperature > 104.0°F (> 40°C) and no previous treatments of disease were randomly allocated to treatment with either tildipirosin or tulathromycin in a 1:1 ratio within lot. Eligible lots included 2 different risk categories: 1) calves with low or moderate risk of developing BRD that did not receive a metaphylactic antimicrobial at arrival, or 2) calves determined to be at high risk of developing BRD that were administered a metaphylactic antimicrobial (tilmicosin) at arrival processing. Calves were returned to their home pen immediately after treatment and were monitored for 60 days. All enrolled animals which died during the study were necropsied by a veterinarian or trained feedlot personnel. Data were evaluated with generalized linear mixed models including lot as random effect comparing treatment groups and metaphylaxis status. No differences were observed (P>0.12) in health outcomes between the 2 treatment groups. Also, there were no differences in first treatment success or case fatality rate in calves with differing metaphylaxis status. Tildipirosin and tulathromycin were both effective antimicrobials for first treatment of BRD in medium- to low-risk populations of feedlot cattle.