Microbiological and histopathological findings in cases of fatal bovine respiratory disease of feedlot cattle in Western Canada.
The aim of this study was to describe the microbiologic agents and pathologic processes in fatal bovine respiratory disease (BRD) of feedlot cattle and to investigate associations between agents and pathologic processes. Ninety feedlot calves diagnosed at necropsy with BRD and 9 control calves without BRD were examined, using immunohistochemical (IHC) staining and histopathologic studies. Mannheimia haemolytica (MH) (peracute, acute, and subacute cases) and Mycoplasma bovis (MB) (subacute, bronchiolar, and chronic cases) were the most common agents identified in fatal BRD cases. Significant associations (P < 0.10) were detected between microbiologic agents and between agents and pathologic processes. When IHC staining was used, 25/26 (96%) of animals that were positive for bovine viral diarrhea virus (BVDV) were also positive for MH; 12/15 (80 %) of animals that were positive for Histophilus somni (HS) were also positive for MB; and all of the animals that were positive for HS were negative for MH and BVDV. This quantitative pathological study demonstrates that several etiologic agents and pathologic processes are involved in fatal BRD of feedlot cattle.
Feedlot Health Management Services Ltd., PO Box 140, Okotoks, Alberta T1S 2A2. calvinb@feedlothealth.com
Calvin W
CW
Booker
Sameeh M
SM
Abutarbush
Paul S
PS
Morley
G Kee
GK
Jim
Tom J
TJ
Pittman
Oliver C
OC
Schunicht
Tye
T
Perrett
Brian K
BK
Wildman
R Kent
RK
Fenton
P Timothy
PT
Guichon
Eugene D
ED
Janzen
D000818:Animals; D048090:Bovine Respiratory Disease Complex / Q000382:microbiology* / Q000401:mortality / Q000473:pathology* / Q000821:virology; D002170:Canada; D002417:Cattle; D001908:Diarrhea Viruses, Bovine Viral / Q000302:isolation & purification*; D005260:Female; D007150:Immunohistochemistry / Q000662:veterinary; D008297:Male; D016978:Mannheimia haemolytica / Q000302:isolation & purification*; D045682:Mycoplasma bovis / Q000302:isolation & purification*; D015661:Pasteurellaceae / Q000302:isolation & purification*