Microbiologic findings in feedlot cattle with acute interstitial pneumonia.
OBJECTIVE
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.


METHODS
Lung and liver specimens were obtained postmortem for bacterial or mycoplasmal culture and histologic examination; lung tissue was assessed for BRSV infection immunohistochemically.


RESULTS
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.


CONCLUSIONS
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.
Woolums
Amelia R
AR
Department of Large Animal Medicine, College of Veterinary Medicine, University of Georgia, Athens, GA 30602, USA.
Mason
Gary L
GL
Hawkins
Larry L
LL
Brown
Corrie C
CC
Williams
Shamita M
SM
Gould
Jared A
JA
Fox
Jocelyn J
JJ
Sturgeon
Scott D
SD
Anderson
Jenny L
JL
Duggan
Florence E
FE
Sanchez
Susan
S
Barrett
Paula B
PB
Chitwood
Sharon W
SW
D000818:Animals; D002417:Cattle; D002418:Cattle Diseases / Q000382:microbiology* / Q000821:virology*; D003120:Colorado; D006652:Histological Techniques; D007150:Immunohistochemistry; D007615:Kansas; D008099:Liver / Q000382:microbiology / Q000821:virology; D008168:Lung / Q000382:microbiology / Q000821:virology; D017563:Lung Diseases, Interstitial / Q000382:microbiology / Q000662:veterinary*; D018112:Respiratory Syncytial Virus, Bovine; D012141:Respiratory Tract Infections / Q000382:microbiology / Q000662:veterinary*