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)
Objective—To compare shedding patterns and serologic responses to bovine coronavirus (BCV) in feedlot calves shipped from a single ranch in New Mexico (NM calves) versus calves assembled from local sale barns in Arkansas (AR calves) and to evaluate the role of BCV on disease and performance.
Animals—103 feedlot calves from New Mexico and 100 from Arkansas.
Procedures—Calves were studied from before shipping to 35 days after arrival at the feedlot. Nasal swab specimens, fecal samples, and serum samples were obtained before shipping, at arrival, and periodically thereafter. Bovine coronavirus antigen and antibodies were detected by use of an ELISA.
Results—NM calves had a high geometric mean titer for BCV antibody at arrival (GMT, 1,928); only 2% shed BCV in nasal secretions and 1% in feces. In contrast, AR calves had low antibody titers against BCV at arrival (GMT, 102) and 64% shed BCV in nasal secretions and 65% in feces. Detection of BCV in nasal secretions preceded detection in feces before shipping AR calves, but at arrival, 73% of AR calves were shedding BCV in nasal secretions and feces. Bovine coronavirus infection was significantly associated with respiratory tract disease and decreased growth performance in AR calves.
Conclusions and Clinical Relevance—Replication and shedding of BCV may start in the upper respiratory tract and spread to the gastrointestinal tract. Vaccination of calves against BCV before shipping to feedlots may provide protection against BCV infection and its effects with other pathogens in the induction of respiratory tract disease.
Objective—To determine sensitivity and specificity of
radiography, ultrasonography, and antegrade pyelography
for detection of ureteral obstructions in cats.
Procedure—Medical records of cats that had radiography,
ultrasonography, and antegrade pyelography
performed for suspected ureteral obstructions were
examined. Ultrasound-guided pyelocentesis and fluoroscopic-
assisted antegrade pyelography were performed
on 18 kidneys in 11 cats. Obstructive ureteral
lesions were confirmed in all cats by surgical or
necropsy examination. Sensitivity and specificity of
survey radiography, ultrasonography, and antegrade
pyelography for identification of ureteral obstructions
were calculated. Surgical or necropsy findings were
used as the standard for comparison.
Results—All cats were azotemic. Mean ± SD serum
creatinine and BUN concentrations were 10.2 ± 6.1
and 149 ± 82 mg/dL, respectively. Fifteen of 18
ureters were found to be obstructed at surgery or
necropsy. Sensitivity and specificity were 60 and
100% for radiography and 100 and 33% for ultrasonography,
respectively, in identification of ureteral
obstructions. Leakage of contrast material developed
in 8 of 18 kidneys during antegrade pyelography and
prevented diagnostic interpretation in 5 of 18 studies.
For the 13 diagnostic studies, specificity and sensitivity
were 100% by use of the antegrade pyelography
technique. Correct identification of the anatomic location
of the ureteral obstruction was obtained in 100%
of diagnostic antegrade pyelography studies and in
60% of radiography or ultrasonography studies.
Conclusions and Clinical Relevance—Antegrade
pyelography can be a useful alternative in the diagnosis
and localization of ureteral obstructions in
azotemic cats, although leakage of contrast material
may prevent interpretation of the study. (J Am Vet
Med Assoc 2003;222:1576–1581)
Objective—To investigate the effect of opsonization of Rhodococcus equi with R equi-specific antibodies in plasma on bacterial viability and phagocyte activation in a cell culture model of infection.
Sample—Neutrophils and monocyte-derived macrophages from 6 healthy 1-week-old foals and 1 adult horse.
Procedures—Foal and adult horse phagocytes were incubated with either opsonized or nonopsonized bacteria. Opsonization was achieved by use of plasma containing high or low concentrations of R equi-specific antibodies. Phagocyte oxidative burst activity was measured by use of flow cytometry, and macrophage tumor necrosis factor (TNF)-α production was measured via an ELISA. Extracellular and intracellular bacterial viability was measured with a novel R equi-luciferase construct that used a luminometer.
Results—Opsonized bacteria increased oxidative burst activity in adult horse phagocytes, and neutrophil activity was dependent on the concentration of specific antibody. Secretion of TNF-α was higher in macrophages infected with opsonized bacteria. Opsonization had no significant effect on bacterial viability in macrophages; however, extracellular bacterial viability was decreased in broth containing plasma with R equi-specific antibodies, compared with viability in broth alone.
Conclusions and Clinical Relevance—The use of plasma enriched with specific antibodies for the opsonization of R equi increased the activation of phagocytes and decreased bacterial viability in the extracellular space. Although opsonized R equi increased TNF-α secretion and oxidative burst in macrophages, additional factors may be necessary for effective intracellular bacterial killing. These data have suggested a possible role of plasma antibody in protection of foals from R equi pneumonia.