A randomized controlled trial evaluating the efficacy of systemic ceftiofur administration for metritis therapy in dairy cows and the effect of metritis cure on economically important outcomes.

The main objective of this study was to evaluate the effect of ceftiofur on metritis cure, milk yield, reproductive performance, and culling up to 300 DIM. The secondary objective was to evaluate the effect of metritis cure at 5 (ECURE) and 14 (LCURE) d after diagnosis on milk production, reproduction, and culling. A total of 422 Holstein cows diagnosed with metritis from 4 herds located in TX, CA, and FL were enrolled in a randomized clinical trial. Cows diagnosed with metritis (fetid, watery, reddish/brownish uterine discharge) were blocked by herd and parity and were randomly allocated to receive systemic administration of ceftiofur (CEF) or to remain untreated (CON). In addition, 399 non-metritic cows (NMET) were included for comparison purposes. Metritis cure was evaluated at 5 and 14 d after diagnosis and was defined as the absence of metritis clinical signs. Logistic regression models were fitted to the data to assess the effect of treatment on metritis cure. Milk yield was analyzed using a mixed linear model, while logistic regression, Cox proportional hazard and Kaplan-Meier survival analysis models were fitted to culling and reproduction data. Cows treated with CEF had 1.86 (95% CI: 1.22 - 2.81) and 1.68 (95% CI: 1.02 - 2.75) greater odds of being cured than CON cows at 5 and 14 d after diagnosis, respectively. No effect of CEF was observed for milk yield; however, NMET cows had greater milk yield compared with metritic cows (CEF = 36.0, 95% CI = 33.8 - 38.1; CON = 36.1, 95% CI = 33.9 - 38.2; NMET = 36.9 kg/d, 95% CI = 34.8 - 39.4). Likewise, no effect of CEF was observed on reproductive performance and culling. Nonetheless, the likelihood of conceiving for NMET cows was 1.72 (95% CI = 1.41 - 2.12) and 1.64 (95% CI = 1.33 - 2.00) times greater than for CEF and CON cows, respectively. Ceftiofur-treated and CON cows had 2.93 (95% CI = 1.90 - 4.51) and 2.37 (95% CI = 1.51 - 3.71) greater hazard of culling compared with NMET, respectively. Regardless of treatment, no differences between ECURE and LCURE were observed on milk yield, reproduction, and culling throughout the entire lactation, but cows that cured at 5 or 14 d after diagnosis had greater milk production in the first 60 DIM compared with cows that did not cure (NCURE). Cows in ECURE and LCURE also had a 1.59 (95% CI = 1.16 - 2.16) and 1.49 (95% CI = 1.08 - 2.05) greater hazard of pregnancy and 0.43 (95% CI = 0.26-0.71) and 0.56 (95% CI = 0.34-0.92) hazard of culling compared with NCURE. Ceftiofur therapy increased metritis cure, but benefits to productivity and longevity were not observed. Also, cows that fail to cure have impaired lactation performance, but no differences regarding timing of cure were observed.