title: Pathogens, patterns of pneumonia, and epidemiologic risk factors associated with respiratory disease in recently weaned cattle in Ireland.
abstract: We examined the pathogens, morphologic patterns, and risk factors associated with bovine respiratory disease (BRD) in 136 recently weaned cattle ("weanlings"), 6-12 mo of age, that were submitted for postmortem examination to regional veterinary laboratories in Ireland. A standardized sampling protocol included routine microbiologic investigations as well as polymerase chain reaction and immunohistochemistry. Lungs with histologic lesions were categorized into 1 of 5 morphologic patterns of pneumonia. Fibrinosuppurative bronchopneumonia (49%) and interstitial pneumonia (48%) were the morphologic patterns recorded most frequently. The various morphologic patterns of pulmonary lesions suggest the involvement of variable combinations of initiating and compounding infectious agents that hindered any simple classification of the etiopathogenesis of the pneumonias. Dual infections were detected in 58% of lungs, with Mannheimia haemolytica and Histophilus somni most frequently recorded in concert. M. haemolytica (43%) was the most frequently detected respiratory pathogen; H. somni was also shown to be frequently implicated in pneumonia in this age group of cattle. Bovine parainfluenza virus 3 (BPIV-3) and Bovine respiratory syncytial virus (16% each) were the viral agents detected most frequently. Potential respiratory pathogens (particularly Pasteurella multocida, BPIV-3, and H. somni) were frequently detected (64%) in lungs that had neither gross nor histologic pulmonary lesions, raising questions regarding their role in the pathogenesis of BRD. The breadth of respiratory pathogens detected in bovine lungs by various detection methods highlights the diagnostic value of parallel analyses in respiratory disease postmortem investigation.
authors.affiliation: Sligo Regional Veterinary Laboratory, Department of Agriculture, Food and Marine, Doonally, Sligo, Ireland
authors.forename: Gerard M
authors.initials: GM
authors.lastname: Murray
authors.affiliation: School of Veterinary Medicine, University College Dublin, Belfield, Dublin 4, Ireland
authors.forename: Simon J
authors.initials: SJ
authors.lastname: More
authors.affiliation: Central Veterinary Research Laboratory, Department of Agriculture, Food and Marine, Celbridge, Co. Kildare, Ireland
authors.forename: Dónal
authors.initials: D
authors.lastname: Sammin
authors.affiliation: Central Veterinary Research Laboratory, Department of Agriculture, Food and Marine, Celbridge, Co. Kildare, Ireland
authors.forename: Mìcheàl J
authors.initials: MJ
authors.lastname: Casey
authors.affiliation: Central Veterinary Research Laboratory, Department of Agriculture, Food and Marine, Celbridge, Co. Kildare, Ireland
authors.forename: Máire C
authors.initials: MC
authors.lastname: McElroy
authors.affiliation: Central Veterinary Research Laboratory, Department of Agriculture, Food and Marine, Celbridge, Co. Kildare, Ireland
authors.forename: Rónan G
authors.initials: RG
authors.lastname: O'Neill
authors.affiliation: Central Veterinary Research Laboratory, Department of Agriculture, Food and Marine, Celbridge, Co. Kildare, Ireland
authors.forename: William J
authors.initials: WJ
authors.lastname: Byrne
authors.affiliation: Animal and Bioscience Research Department, Animal & Grassland Research and Innovation Centre, Teagasc, Dunsany, Grange, Co. Meath, Ireland
authors.forename: Bernadette
authors.initials: B
authors.lastname: Earley
authors.affiliation: School of Veterinary Medicine, University College Dublin, Belfield, Dublin 4, Ireland
authors.forename: Tracy A
authors.initials: TA
authors.lastname: Clegg
authors.affiliation: Agri-food and Biosciences Institute, Veterinary Sciences Division, Stormont, Belfast, Northern Ireland
authors.forename: Hywel
authors.initials: H
authors.lastname: Ball
authors.affiliation: Agri-food and Biosciences Institute, Veterinary Sciences Division, Stormont, Belfast, Northern Ireland
authors.forename: Colin J
authors.initials: CJ
authors.lastname: Bell
authors.affiliation: School of Veterinary Medicine, University College Dublin, Belfield, Dublin 4, Ireland
authors.forename: Joseph P
authors.initials: JP
authors.lastname: Cassidy
mesh_terms: D000818:Animals; D000833:Animals, Suckling; D001344:Autopsy / Q000662:veterinary; D001996:Bronchopneumonia / Q000453:epidemiology / Q000662:veterinary*; D002417:Cattle; D002418:Cattle Diseases / Q000175:diagnosis / Q000453:epidemiology* / Q000382:microbiology; D007150:Immunohistochemistry / Q000662:veterinary; D007494:Ireland / Q000453:epidemiology; D016978:Mannheimia haemolytica / Q000302:isolation & purification; D029101:Parainfluenza Virus 3, Bovine / Q000302:isolation & purification; D016979:Pasteurella multocida / Q000302:isolation & purification; D016133:Polymerase Chain Reaction / Q000662:veterinary; D018112:Respiratory Syncytial Virus, Bovine / Q000302:isolation & purification
keywords: Bovine respiratory disease; lungs; pathology; postmortem; risk factors; weanling