Microbiologic findings in feedlot cattle with acute interstitial pneumonia

• Published in: American journal of veterinary research Vol. 65; no. 11; pp. 1525 - 1532
• Main Authors: Woolums, A.R, Mason, G.L, Hawkins, L.L, Brown, C.C, Williams, S.M, Gould, J.A, Fox, J.J, Sturgeon, S.D, Anderson, J.L, Duggan, F.E
• Format: Journal Article
• Language: English
• Published: United States 01.11.2004
• Subjects: acute course; acute interstitial pneumonia; Animals; bacterial pneumonia; Bovine respiratory syncytial virus; Cattle; cattle diseases; Cattle Diseases - microbiology; Cattle Diseases - virology; Colorado; disease diagnosis; feedlots; Histological Techniques; histopathology; hyperplasia; Immunohistochemistry; Kansas; lesions (animal); liver; Liver - microbiology; Liver - virology; liver abscess; Lung - microbiology; Lung - virology; Lung Diseases, Interstitial - microbiology; Lung Diseases, Interstitial - veterinary; lungs; mixed infection; Respiratory Syncytial Virus, Bovine; Respiratory Tract Infections - microbiology; Respiratory Tract Infections - veterinary; viral diseases of animals and humans; Colorado; Kansas
• ISSN: 0002-9645; 1943-5681
• DOI: 10.2460/ajvr.2004.65.1525

To test the hypothesis that feedlot cattle with acute interstitial pneumonia (AIP) have bacterial infection of the lung or liver and concurrent bovine respiratory syncytial virus (BRSV) infection significantly more often than pen mates without AIP ANIMALS: 39 feedlot cattle with signs consistent with AIP and no history of treatment with antimicrobials and 32 healthy control cattle from the same pens. Lung and liver specimens were obtained postmortem for bacterial or mycoplasmal culture and histologic examination; lung tissue was assessed for BRSV infection immunohistochemically. Among affected cattle, 26 had AIP confirmed histologically. Lung tissue from 11 cattle with AIP yielded microbial respiratory tract pathogens on culture; tissues from control animals yielded no microbial growth. In 4 cattle with AIP and 2 control animals, liver abscesses were detected; bacteria were isolated from abscessed tissue in 3 and 1 of those animals, respectively. Immunohistochemically, 9 cattle with AIP and no control animals were BRSV-positive. Histologically, 9 AIP-affected cattle had only acute alveolar damage with exudation, and the other 17 had acute exudation with type II pneumocyte hyperplasia. No lesions of AIP were detected in control animals. Only 4 AIP-affected cattle had bacterial infection of the lung with concurrent BRSV infection. Results indicated that microbial respiratory tract pathogens are more common in cattle with AIP than in healthy pen mates. Control of bacterial pneumonia late in the feeding period may reduce the incidence of AIP at feedlots where AIP is a problem.