Isolation of respiratory bovine coronavirus, other cytocidal viruses, and Pasteurella spp from cattle involved in two natural outbreaks of shipping fever

Objective-To identify cytocidal viruses and Pasteurella spp that could be i solated from cattle involved in 2 natural outbreaks of shipping fever. Animals-105 and 120 castrated male 4- to 8-month-old feedlot cattle involve d in 1997 and 1998 outbreaks, respectively. Procedures-Nasal swab specimens and blood samples were collected, and cattl e were vaccinated on arrival at an order-buyer barn from 4 local auction ho uses. Four days later, they were transported to a feedlot, and additional n asal swab specimens and blood samples were collected. Nasal swab specimens were submitted for virus isolation and bacterial culture; blood samples wer e submitted for measurement of respiratory bovine coronavirus (RBCV) hemagg lutinin inhibition titers. Results-93 of 105 cattle and 106 of 120 cattle developed signs of respirato ry tract disease during 1997 and 1998, respectively, and RBCV was isolated from 81 and 89 sick cattle, respectively while at the order-buyer's barn or the day after arrival at the feedlot. During the 1997 outbreak, bovine her pesvirus 1 was isolated from 2 cattle at the order-buyer's barn and from 5 cattle 7 and 14 days after arrival at the feedlot, and parainfluenza virus 3 was isolated from 4 cattle 14 days after arrival at the feedlot. During t he 1998 outbreak, bovine herpesvirus 1 was isolated from 2 cattle at the or der-buyer's barn and on arrival at the feedlot and from 5 cattle 7 and 14 d ays after arrival at the feedlot, and parainfluenza virus 3 was isolated fr om 1 animal the day of, and from 18 cattle 7 and 14 days after, arrival at the feedlot. Pasteurella spp was cultured from 4 and 6 cattle at the order- buyer's barn and from 92 and 72 cattle on arrival at the feedlot during the 1997 and 1998 outbreaks, respectively. Conclusions and Clinical Relevance-Results suggest that RBCV may play a cau sative role in outbreaks of shipping fever in cattle. More than 80% of the sick cattle shed RBCV at the beginning of 2 outbreaks when the Pasteurella spp infection rate was low.