Objective—To measure antibody titers against
bovine coronavirus (BCV), determine frequency of
BCV in nasal swab specimens, and compare calves
treated for bovine respiratory tract disease (BRD)
between those given an intranasally administered
vaccine and control calves.
Design—Randomized clinical trial.
Animals—414 heifer calves.
Procedure—Intranasal BCV antigen concentration
and antibody titer against BCV were measured on
entry to a feedlot. Calves were randomly assigned to
receive 3.0 mL of a modified-live virus vaccine against
bovine enteric coronavirus and rotavirus or 3.0 mL of
saline (0.9% NaCl) solution. Calves were confined to
1 of 2 pens, depending on vaccination status, for a
minimum of 17 days of observation (range, 17 to 99).
Selection of calves for treatment of BRD and scoring
for severity of disease were done by veterinarians
unaware of treatment status.
Results—Intranasal BCV (125/407 [31%]) and serum
antibody titers ≥ 20 against BCV (246/396 [62%])
were identified in calves entering the feedlot.
Vaccination was associated with significant decrease
in risk of treatment for BRD; intranasal BCV on entry
to the feedlot was associated with increased risk of
treatment. Univariate analysis revealed that control
calves with intranasal BRD on entry to the feedlot and
those with antibody titer < 20 were significantly more
likely to be treated for BRD.
Conclusions and Clinical Relevance—These data
provide further evidence of an association between
BCV and respiratory tract disease in feedlot calves.
An intranasally administered vaccine appeared to
reduce risk of treatment for BRD. (J Am Vet Med
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
Procedure—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 and Clinical Relevance—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. (Am J Vet Res 2004;65:1525–1532)