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- Author or Editor: Delbert G. Miles x
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Objective—To evaluate viral and bacterial respiratory pathogens and Mycoplasma spp isolated from lung tissues of cattle with acute interstitial pneumonia (AIP) and cattle that had died as a result of other causes.
Sample Population—186 samples of lung tissues collected from cattle housed in 14 feedlots in the western United States.
Procedure—Lung tissues were collected during routine postmortem examination and submitted for histologic, microbiologic, and toxicologic examinations. Histologic diagnoses were categorized for AIP, bronchopneumonia (BP), control samples (no evidence of disease), and other disorders.
Results—Cattle affected with AIP had been in feedlots for a mean of 127.2 days before death, which was longer than cattle with BP and control cattle. Detection of a viral respiratory pathogen (eg, bovine respiratory syncytial virus [BRSV], bovine viral diarrhea virus, bovine herpesvirus 1, or parainfluenza virus 3) was not associated with histologic category of lung tissues. Bovine respiratory syncytial virus was detected in 8.3% of AIP samples and 24.0% of control samples. Histologic category was associated with isolation of an aerobic bacterial agent and Mycoplasma spp. Cattle with BP were at greatest risk for isolation of an aerobic bacterial agent and Mycoplasma spp.
Conclusion and Clinical Relevance—Analysis of these results suggests that AIP in feedlot cattle is not a consequence of infection with BRSV. The increased risk of isolation of an aerobic bacterial agent from cattle with AIP, compared with control cattle, may indicate a causal role or an opportunistic infection that follows development of AIP. (Am J Vet Res 2001; 62:1519–1524)
Objective—To compare concentrations of 3-methyleneindolenine (3MEIN) in lung tissues obtained from feedlot cattle that died as a result of acute interstitial pneumonia (AIP) and cattle that died as a result of other causes and to compare blood concentrations of 3MEIN in healthy feedlot cattle and feedlot cattle with AIP.
Study Population—Blood samples and lung tissues collected from 186 cattle housed in 14 feedlots in the western United States.
Procedure—Samples of lung tissues were collected during routine postmortem examination and submitted for histologic, microbiologic, and toxicologic examination. Blood samples were collected from cattle with clinical manifestations of AIP and healthy penmates. Histologic diagnoses were categorized as AIP, bronchopneumonia (BP), control samples, and other disorders. Concentrations of 3MEIN were determined in lung tissues and blood samples, using an ELISA.
Results—Concentrations of 3MEIN in lung tissues were significantly greater in AIP and BP samples, compared with control samples. Absorbance per microgram of protein did not differ between BP and AIP samples. Blood concentrations of 3MEIN were significantly greater in cattle with AIP, compared with healthy cattle or cattle with BP. Odds of an animal with AIP being a heifer was 3.1 times greater than the odds of that animal being a steer.
Conclusion and Clinical Relevance—Increased pulmonary production of 3MEIN may be an important etiologic factor in feedlot-associated AIP. (Am J Vet Res 2001;62:1525–1530)