Health outcomes following antimicrobial treatment of septic arthritis in Canadian feedlot calves.

Objective: To assess the clinical efficacy of treating septic arthritis (SA) with 3 different antimicrobials: oxytetracycline, florfenicol, and tulathromycin.

Animal: The study population comprised fall-placed steer and heifer calves at 4 commercial western Canadian feedlots. All calves received tulathromycin at induction for bovine respiratory disease (BRD).

Procedure: Calves that developed SA were allocated to a randomized clinical field trial over a 2-year period. Arthritic calves (n = 251) were treated with florfenicol, oxytetracycline, or tulathromycin. Morbidity outcomes were SA relapses (1st and 2nd) and BRD. Causes of mortality were categorized as infectious (BRD, Histophilus somni, SA) and SA alone. Additional outcomes were early shipment for salvage slaughter (railer) and the sum of infectious mortality events and railer events (total fallout). Calves were followed for 90 d post-allocation.

Results: The numbers of calves allocated to florfenicol, oxytetracycline, and tulathromycin treatments were 85, 81, and 85, respectively. There were no differences in health outcomes among antimicrobial treatments (P > 0.05).

Conclusion: This clinical field trial identified no health outcome differences when comparing florfenicol, oxytetracycline, and tulathromycin for the 1st treatment of SA in feedlot calves.

Clinical relevance: Practitioners can use these results when creating treatment protocols for SA cases. Since results indicated similar health outcomes among the 3 antimicrobials, the lowest-priced antimicrobial may be the most cost-effective option. Perhaps antimicrobial treatment does not affect SA outcomes, but this could not be determined as negative controls were not included in this study.