Objective—To determine the prevalence, fecal shedding
pattern, and association of bovine torovirus
(BoTV) with diarrhea in veal calves at time of arrival
and periodically throughout the first 35 days after their
arrival on a veal farm.
Animals—62 veal calves.
Procedure—Fecal samples collected on days 0, 4, 14,
and 35 after arrival were tested for BoTV by use of
ELISA and reverse transcriptase-polymerase chain
reaction (RT-PCR) assay. Paired serum samples
obtained from blood collected on days 0 and 35 were
analyzed for BoTV antibodies with a hemagglutination
inhibition assay. Fecal samples were also screened
for other enteric pathogens, including rotavirus, coronavirus,
and Cryptosporidium spp.
Results—Fecal shedding of BoTV was detected in 15
of 62 (24%) calves by use of ELISA and RT-PCR assay,
with peak shedding on day 4. A significant independent
association between BoTV shedding and diarrhea
was observed. In addition, calves shedding ≥ 2
enteric pathogens were more likely to have diarrhea
than calves shedding ≤ 1 pathogen. Calves that were
seronegative or had low antibody titers against BoTV
(≤ 1:10 hemagglutination inhibition units) at arrival
seroconverted to BoTV (> 4-fold increase in titer);
these calves were more likely to shed virus than
calves that were seropositive against BoTV at arrival.
Conclusions and Clinical Relevance—Shedding of
BoTV was strongly associated with diarrhea in neonatal
veal calves during the first week after arrival at the
farm. These data provide evidence that BoTV is an
important pathogen of neonatal veal calves.
(Am J Vet Res 2003;64:485–490)