CORONAVIRUS ISOLATION FROM NASAL SWAB SAMPLES IN CATTLE WITH SIGNS OFRESPIRATORY-TRACT DISEASE AFTER SHIPPING

Objective-To monitor the prevailing viral respiratory tract infections in cattle after transportation to feedlots. Animals-100 cattle with s igns of respiratory tract disease on arrival at 2 feedlots. Procedures -Nasal swab samples were obtained from each animal and were used for i noculation of defined cell culture systems that detected bovine viruse s known to cause respiratory tract infections, as well as viruses prev iously not recognized as respiratory pathogens for cattle. Results-Bov ine respiratory coronaviruses were isolated from 38 of the 100 cattle, including 6 of 50 cattle from California, 22 of 31 cattle from Oklaho ma, 6 of 11 cattle from Texas, and 4 of 8 cattle of unknown origin. Pa rainfluenza 3 viruses also were isolated from 4 California cattle, but other bovine viruses were not detected. Clinical Implications-The hig h rate of coronavirus isolations from feedlot cattle with signs of res piratory tract disease implied wide distribution and high susceptibili ty among cattle to this infection, which had not been detected by use of viral isolation systems in previous etiologic evaluations of feedlo t cattle affected with bovine respiratory disease complex.