OBJECTIVE To evaluate whether a low-dosage regimen of prednisolone induces bone loss and whether administration of alendronate sodium prevents glucocorticoid-induced osteopenia in dogs by measuring trabecular bone mineral density (BMD) with quantitative CT.
ANIMALS 8 healthy Beagles.
PROCEDURES In 4 dogs, prednisolone was administered PO at a dosage of 2 mg/kg once daily for 2 weeks, 1 mg/kg once daily for 4 weeks, and 0.5 mg/kg once daily for 3 weeks. In the other 4 dogs, alendronate sodium (2 mg/kg, PO, q 24 h) was whether administered for 9 weeks in addition to the same dosage of prednisolone used in the prednisolone-treated dogs. Before (day 0 [baseline]) and 21, 42, 63, and 150 days after the start of treatment, BMD of the lumbar vertebrae was measured by quantitative CT.
RESULTS BMD in the prednisolone treatment group decreased to 84.7% of the baseline value on day 42, increased to 87.9% on day 63, and recovered to 91.6% on day 150. In the prednisolone-alendronate treatment group, BMD decreased to 91% of the baseline value on day 21, increased to 93.8% on day 63, and then recovered to 96.7% on day 150. Bone mineral density in the prednisolone treatment group was generally lower, albeit not significantly, than that of the prednisolone-alendronate treatment group on each examination day.
CONCLUSIONS AND CLINICAL RELEVANCE BMD temporarily decreased after low-dosage prednisolone administration; however, it gradually improved during tapering of the prednisolone dosage. These results have suggested that a low dosage of prednisolone can be used with little concern for development of osteopenia in dogs.
Objective—To assess fecal and nasal shedding patterns
of bovine torovirus (BoTV) in cattle at time of
arrival and periodically throughout the first 21 days
after arrival at a feedlot.
Procedure—Fecal and nasal-swab samples collected
on days 0, 4, 14, and 21 after arrival were tested for
BoTV, using ELISA. A subset of samples from calves
testing positive and negative for BoTV was analyzed,
using reverse transcriptase-polymerase chain reaction
(RT-PCR). Paired serum samples were collected on
days 0 and 21 and tested for BoTV antibodies, using
a hemagglutination inhibition assay.
Results—Overall rate of fecal shedding of BoTV was
21 of 57 (37%) by ELISA and 40 of 42 (95%) by
RT-PCR with peak shedding on day 4. Diarrhea was
more common in calves shedding BoTV than those
not shedding the virus (odds ratio, 1.72). Overall rate
of nasal shedding of BoTV was 15 of 57 (26%) by
ELISA and 42 of 42 (100%) by RT-PCR, with peak
shedding on day 0. Specificity of the RT-PCR product
was confirmed by sequence analysis. Approximately
93% of the calves seroconverted to BoTV (> 4-fold
increase in titer). Differences were not detected
between calves shedding BoTV and nonshedders in
relation to disease and treatments, perhaps because
of the low number of cattle in the study.
Conclusions and Clinical Relevance—This study
confirmed BoTV infections in feedlot cattle, including
BoTV antigen and viral RNA in nasal secretions, and
the shedding pattern during the first 21 days after
arrival in a feedlot. (Am J Vet Res 2002;63:342–348).
Objective—To assess the relationship between shedding
of bovine coronavirus (BCV) via the respiratory
tract and enteric routes and the association with
weight gain in feedlot cattle.
Animals—56 crossbred steers.
Procedures—Paired fecal samples and nasal swab
specimens were obtained and were tested for BCV,
using antigen-capture ELISA. Paired serum samples
obtained were tested for antibodies to BCV, using
antibody-detection ELISA. Information was collected
on weight gain, clinical signs, and treatments for
enteric and respiratory tract disease during the study
Results—Number of samples positive for bovine respiratory
coronavirus (BRCV) or bovine enteric coro
navirus (BECV) was 37/224 (17%) and 48/223 (22%),
respectively. Some cattle (25/46, 45%) shed BECV
and BRCV. There were 25/29 (86%) cattle positive for
BECV that shed BRCV, but only 1/27 (4%) cattle negative
to BECV shed BRCV. Twenty-seven of 48 (56%)
paired nasal swab specimens and fecal samples positive
for BECV were positive for BRCV. In contrast,
only 10/175 (6%) paired nasal swab specimens and
fecal samples negative for BECV were positive for
BRCV. Only shedding of BECV was associated with
significantly reduced weight gain. Seroconversion to
BCV during the 21 days after arrival was detected in
95% of the cattle tested.
Conclusions and Clinical Implications—Feedlot
cattle infected with BCV after transport shed BCV
from the respiratory tract and in the feces. Fecal
shedding of BCV was associated with significantly
reduced weight gain. Developing appropriate control
measures for BCV infections could help reduce the
decreased weight gain observed among infected
feedlot cattle. (Am J Vet Res 2001;62:1436–1441)
OBJECTIVE To evaluate acute changes of the liver by use of shear wave elastography (SWE) and CT perfusion after radiofrequency ablation (RFA).
ANIMALS 7 healthy Beagles.
PROCEDURES RFA was performed on the liver (day 0). Stiffness of the ablation lesion, transitional zone, and normal parenchyma were evaluated by use of SWE, and blood flow, blood volume, and arterial liver perfusion of those regions were evaluated by use of CT perfusion on days 0 and 4. All RFA lesions were histologically examined on day 4.
RESULTS Examination of the SWE color-coded map distinctly revealed stiffness of the liver tissue, which increased from the normal parenchyma to the transitional zone and then to the ablation zone. For CT perfusion, blood flow, blood volume, and arterial liver perfusion decreased from the transitional zone to the normal parenchyma and then to the ablation zone. Tissue stiffness and CT perfusion variables did not differ significantly between days 0 and 4. Histologic examination revealed central diffuse necrosis and peripheral hyperemia with infiltration of lymphoid cells and macrophages.
CONCLUSIONS AND CLINICAL RELEVANCE Coagulation necrosis induced a loss of blood perfusion and caused tissue hardening (stiffness) in the ablation zone. Hyperemic and inflammatory changes of the transitional zone resulted in increased blood perfusion. Acute changes in stiffness and perfusion of liver tissue after RFA could be determined by use of SWE and CT perfusion. These results can be used to predict the clinical efficacy of RFA and to support further studies, including those involving hepatic neoplasia.
OBJECTIVE To assess by use of various diagnostic imaging modalities acute changes in livers of healthy dogs after radiofrequency ablation (RFA) and determine the capability of each imaging modality to monitor ablation lesion changes.
ANIMALS 6 healthy Beagles.
PROCEDURES 12 ablation lesions were created in the liver of the dogs (2 lesions/dog). Ablation lesions were evaluated by use of conventional ultrasonography, strain elastography, and contrast-enhanced ultrasonography immediately after (time 0), 30 to 60 minutes after, and 3 days after RFA, and by use of CT 30 minutes and 3 days after RFA. Three dogs were euthanized shortly after RFA, and the other 3 dogs were euthanized on day 3. Lesion size measured by each imaging modality was compared with necropsy findings.
RESULTS Immediately after RFA, clear margins were more visible with elastography and contrast-enhanced ultrasonography than with conventional ultrasonography, which had acoustic shadowing. On triphasic contrast CT, the ablation zone, which indicated necrosis and hemorrhage, was not enhanced and could be measured. Marked enhancement of the periablation rim was observed during the venous phase and was identified as granulation tissue. Size of the ablation area measured on enhanced CT images was strongly correlated with actual lesion size.
CONCLUSIONS AND CLINICAL RELEVANCE For dogs of this study, CT was the most reliable method for lesion size determination. Although ultrasonographic imaging measurements underestimated lesion size, all modalities could be used to provide additional real-time guidance for RFA procedures of the liver as well as for other RFA procedures.