Rhinitis syndrome in IBR-vaccinated feedlot cattle

Abstract

Fourteen feeder cattle that had been vaccinated against IBR with modified live virus at least 21 days previously developed clinical signs of acute rhinitis. IBR virus was isolated from 11 of the 14. Seroconversion to IBR virus occurred in 9 of these 11 cattle and one died acutely. Several of these 11 cattle also seroconverted to bovine diarrhoea virus or bovine parainfluenza-3 virus, but neither of these viruses was isolated from any animal. IBR virus was not isolated from nor did seroconversion to IBR virus occur in the remaining 3 cattle. Another virus, not IBR, was isolated from one of these three. The potential for vaccine failure to protect is discussed.