Making the Antibiotic Choice for Treating Bovine Respiratory Disease

Abstract

BRD produces disease with morbidity peaking in 1-3 weeks and mortality peaking in 2-4 weeks after entering the feedlot.^1,4 When an epidemic curve for BRD is constructed using fatal disease onset rather than mortality as the parameter, it can be seen that calves dying from BRD become ill within the first 2 weeks of entering the feedlot.⁴ The fact that calves become ill so quickly after entering the feedlot obviously puts great emphasis on the type of animal and its recent history. This will be important in determining the morbidity and mortality which may occur. Fall placed calves going into feedlots in Canada and the northern United States will have higher morbidity and mortality than older calves. The morbidity and mortality of fall placed calves in the northern United States will be similar to that seen in stocker calves in southern United States. Both types of calves are young, multiorigin, long haul sale barn calves whose age and handling result in higher BRD morbidity and mortality.⁵ Antimicrobial agents can be used in the feedlot in the traditional manner to control mortality and improve performance in sick calves experiencing BRD as well as prophylactically on arrival to limit both BRD morbidity and mortality.