A randomised clinical trial of a metaphylactic treatment with tildipirosin for bovine respiratory disease in veal calves.

Abstract

BACKGROUND: Bovine respiratory disease (BRD) is a major problem in veal calf rearing units. The objective of this randomised clinical trial was to assess the effectiveness of tildipirosin as a metaphylactic treatment in veal calves on the number of BRD treatments, lung consolidation on thoracic ultrasonography (TUS) and average daily gain (ADG). A total of 209 veal calves from a pre-weaning fattening unit were randomly allocated to receive one of two treatments (tildipirosin 4&#xa0;mg/kg, subcutaneously, n&#xa0;=&#xa0;109; placebo 0.9% saline, subcutaneously, n&#xa0;=&#xa0;100) at day 12 after entry in the pre-weaned unit. The calves were followed for a 70-day period. Occurrence of mortality and BRD treatments were recorded during the pre-weaning period. At days 1, 12 and 30, TUS and clinical scores were performed and ADG was measured during the first and second months of feeding. RESULTS: The use of a metaphylactic treatment of tildipirosin 12&#xa0;days after arrival of the veal calves was not associated with the number of BRD treatments performed by the producer, ultrasonographic lung consolidation or weight gain (P&#xa0;<&#xa0;0,05). In this cohort of calves, the proportion of calves treated for BRD by the producer was low at 14% (29/209). However, 13% (26/209) of calves included in the study already had ultrasonographic lung consolidation lesions 12&#xa0;days after their arrival, which was before treatment time, and 27% (56/209) had lung consolidation at day 30. CONCLUSION: In this study population with a low BRD prevalence, we were not able to detect any benefit of tildipirosin as a metaphylactic treatment of BRD at day 12 after arrival based on BRD treatments, TUS, and ADG.