Objective—To determine the effects of endotoxin
administration on thyroid function test results and serum
tumor necrosis factor-α (TNF-α) activity in healthy dogs.
Animals—6 healthy adult male dogs.
Procedures—Serum concentrations of thyroxine (T4),
3,5,3'-triiodothyronine (T3), 3,3'5'-triiodothyronine
(rT3), free T4 (fT4), and endogenous canine thyroid
stimulating hormone (TSH), and TNF-α activity were
measured before (day–1; baseline), during (days 0 to
3), and after (days 4 to 24) IV administration of endotoxin
every 12 hours for 84 hours.
Results—Compared with baseline values, serum T3
concentration decreased significantly, whereas rT3
concentration increased significantly 8 hours after initial
endotoxin administration. Serum T4 concentration
decreased significantly at 8 and 12 hours after initiating
endotoxin administration. Serum T4 concentration
returned to reference range limits, then decreased
significantly on days 6 to 12 and 16 to 20. Serum fT4
concentration increased significantly at 12, 24, and 48
hours after cessation of endotoxin treatment, compared
with baseline values. Serum rT3 concentration
returned to reference range, then decreased significantly
days 5 and 7 after stopping endotoxin treatment.
Serum TNF-α activity was significantly
increased only 4 hours after initial endotoxin treatment,
compared with baseline activity.
Conclusions and Clinical Relevance—Endotoxin
administration modeled alterations in thyroid function
test results found in dogs with spontaneous nonthyroidal
illness syndrome. A decrease in serum T4 and T3
concentrations and increase in serum rT3 concentration
indicate impaired secretion and metabolism of
thyroid hormones. The persistent decrease in serum
T4 concentration indicates that caution should be
used in interpreting serum T4 concentrations after resolution
of an illness in dogs. (Am J Vet Res 2003;64:229–234)
Objective—To evaluate the effects of deracoxib and aspirin on serum concentrations of thyroxine (T4), 3,5,3′-triiodothyronine (T3), free thyroxine (fT4), and thyroid-stimulating hormone (TSH) in healthy dogs.
Procedure—Dogs were allocated to 1 of 3 groups of 8 dogs each. Dogs received the vehicle used for deracoxib tablets (PO, q 8 h; placebo), aspirin (23 to 25 mg/kg, PO, q 8 h), or deracoxib (1.25 to 1.8 mg/kg, PO, q 24 h) and placebo (PO, q 8 h) for 28 days. Measurement of serum concentrations of T4, T3, fT4, and TSH were performed 7 days before treatment (day −7), on days 14 and 28 of treatment, and 14 days after treatment was discontinued. Plasma total protein, albumin, and globulin concentrations were measured on days −7 and 28.
Results—Mean serum T4, fT4, and T3 concentrations decreased significantly from baseline on days 14 and 28 of treatment in dogs receiving aspirin, compared with those receiving placebo. Mean plasma total protein, albumin, and globulin concentrations on day 28 decreased significantly in dogs receiving aspirin, compared with those receiving placebo. Fourteen days after administration of aspirin was stopped, differences in hormone concentrations were no longer significant. Differences in serum TSH or the free fraction of T4 were not detected at any time. No significant difference in any of the analytes was detected at any time in dogs treated with deracoxib.
Conclusions and Clinical Relevance—Aspirin had substantial suppressive effects on thyroid hormone concentrations in dogs. Treatment with high dosages of aspirin, but not deracoxib, should be discontinued prior to evaluation of thyroid function.
Objective—To compare results of a nonradioactive
colorimetric microplate assay with results of a traditional
radioactive proliferation assay for determination
of its use as a reliable and accurate alternative
method for determination of proliferative activity of
Sample Population—Blood samples from 10 clinically
normal domestic shorthair cats.
Procedure—Double-density gradient separation was
used to isolate mononuclear cells. Isolated cells were
stimulated with various concentrations of concanavalin
A (Con-A) and cultured for 72 hours.
Lymphocyte proliferation was measured by radioactive
([3H]thymidine) and nonradioactive (colorimetric)
techniques. Immunophenotypic analysis with felinespecific
CD4+ and CD8+ monoclonal antibody was performed,
using flow cytometry.
Results—Mononuclear cells were successfully isolated
(97 to 99% purity and viability) from blood samples.
A similar dose-dependent proliferative response
to Con-A stimulation was measured with [3H]thymidine
incorporation and the colorimetric assay. For
both techniques, concentrations of 0.1 and 1.0 µg of
Con-A/ml were submitogenic, and 100 µg/ml was
toxic to cultured cells. For both techniques, maximal
proliferation was observed with 5 µg of Con-A/ml.
Conclusion and Clinical Relevance—These results
indicate that the nonradioactive colorimetric technique
is a reliable and accurate method for measuring
proliferative activity of feline lymphocytes. Clinically,
this assay can be used as part of a screening process
to determine immunocompetence of at-risk cats and
to evaluate treatments for cats with immune-mediated
or T-cell-dependent diseases. (Am J Vet Res 2001;
Objective—To evaluate the hemodynamic effects
of orally administered carvedilol in healthy dogs
with doses that might be used to initiate treatment
in dogs with congestive heart failure.
Animals—24 healthy dogs.
Procedure—Dogs were randomly allocated to
receive carvedilol PO at a dose of 1.56, 3.125, or
12.5 mg, twice daily for 7 to 10 days; 6 dogs served
as controls. Investigators were blinded to group
assignment. Hemodynamic variables were recorded
prior to administration of the drug on day 1 and
then 2, 4, and 6 hours after the morning dose on
day 1 and days 7 to 10. Change in heart rate after IV
administration of 1 µg of isoproterenol/kg and
change in systemic arterial blood pressure after IV
administration of 8 µg of phenylephrine/kg were
recorded 2 and 6 hours after administration of
Results—Administration of carvedilol did not significantly
affect resting hemodynamic variables or
response to phenylephrine. The interaction of day
and carvedilol dose had a significant effect on resting
heart rate, but a significant main effect of
carvedilol dose on resting heart rate was not detected.
Increasing carvedilol dose resulted in a significant
linear decrease in heart rate response to isoproterenol.
Conclusions and Clinical Relevance—In healthy
conscious dogs, orally administered carvedilol at
mean doses from 0.08 to 0.54 mg/kg given twice
daily did not affect resting hemodynamics. Over
the dose range evaluated, there was a dose-dependent
attenuation of the response to isoproterenol,
which provided evidence of β-adrenergic receptor
antagonism. (Am J Vet Res 2005;66:637–641)
Objective—To determine the duration of effect and
the effect of multiple doses of topical ophthalmic
application of 0.5% proparacaine hydrochloride on
corneal sensitivity in clinically normal dogs.
Animals—8 clinically normal dogs.
Procedure—Dogs were randomly allocated to treatment
order in a 2 × 2 (period × treatment) crossover
study. Treatments consisted of topical application of
ophthalmic 0.5% proparacaine (1 drop or 2 drops at a
1-minute interval); treatments were applied to both
eyes. A Cochet-Bonnet aesthesiometer was used to
determine corneal touch threshold (CTT) before
corneal application, 1 and 5 minutes after corneal
application, and at 5-minute intervals thereafter for 90
Results—The CTT value before treatment differed
significantly from CTT values after treatment until 45
minutes after application in the 1-drop group and until
55 minutes after application in the 2-drop group. As
determined by use of the Cochet-Bonnet aesthesiometer,
a significantly greater anesthetic effect was
detected for the 2-drop treatment, compared with the
effect for the 1-drop treatment, at 30, 35, 40, 45, 50,
and 55 minutes after application. Maximal anesthetic
effect lasted for 15 minutes for the 1-drop treatment
and 25 minutes for the 2-drop treatment.
Conclusions and Clinical Relevance—Duration of
corneal anesthetic effect induced by topical ophthalmic
application of 0.5% proparacaine in dogs of
this study is considerably longer than that reported
elsewhere. Serial application of doses of 0.5%
proparacaine increases the duration and magnitude of
corneal anesthetic effects. (Am J Vet Res 2005;66:77–80)
Objective—To determine whether results of magnetic
resonance imaging (MRI) and computed tomography
(CT) are associated with postoperative outcome in
working dogs with degenerative lumbosacral stenosis.
Design—Prospective cohort study.
Animals—12 dogs treated surgically for degenerative
Procedure—Procedure—The lumbosacral vertebral column was
examined before surgery by use of MRI and CT and
after surgery by use of CT. Outcome, based on performance
in standardized training exercises, was
assessed 6 months after decompressive surgery.
Associations between imaging results and postoperative
outcome were determined by use of a Fisher
exact test and logistic regression.
Results—None of the dogs were able to perform
their duties before surgery. By 6 months after
surgery, 8 of 12 dogs had been returned to full active
duty. Nerve tissue compression was effectively localized
by use of CT and MRI. Significant associations
between results of imaging studies and postoperative
outcome were not identified.
Conclusions and Clinical Relevance—Surgical intervention
is justified in high-performance working dogs
with degenerative lumbosacral stenosis. However,
results of imaging studies may be less important than
clinical or surgical factors for predicting outcome in affected
dogs. (J Am Vet Med Assoc 2000;216:1769–1774)
Objective—To identify apoptosis in equine intestines
and determine whether apoptosis is associated with
gastrointestinal tract disease or a specific tissue layer
Animals—38 horses that underwent surgery or were
euthanatized for small or large intestine obstruction,
strangulation, or distension and 9 control horses
euthanatized for reasons other than gastrointestinal
tract disease or systemic disease.
Procedure—Specimens were collected at surgery
from intestine involved in the primary lesion and distant
to the primary lesion site or at necropsy from
several sites including the primary lesion site.
Histologic tissue sections were stained with H&E,
and apoptosis was detected by use of the terminal
deoxynucleotidyl transferase-mediated dUTP nick end
labeling technique. The number of apoptotic cells per
hpf was counted in the mucosa, circular muscle, longitudinal
muscle, and serosa.
Results—Apoptotic nuclei were seen in all layers of
intestine. An increased number of apoptotic cells was
found in the circular muscle of the intestine from horses
with simple obstruction, compared with strangulating
obstruction or healthy intestine. Intestine distant
from a primary strangulating lesion had higher numbers
of apoptotic cells than did intestine distant from
a simple obstructive lesion or intestine taken at the
site of a strangulating or simple obstructive lesion.
Conclusions and Clinical Relevance—Intestine
from horses with obstructing or strangulating lesions
in the small intestine and large colon had high numbers
of apoptotic cells possibly because of ischemic
cell injury and subsequent inflammation. Whether
substantial apoptosis affects intestinal function is not
yet known. (Am J Vet Res 2003;64:982–988)
Objective—To describe the anatomic features of the
pituitary gland region in horses via computed tomography
(CT) and determine the accuracy of CT for estimating
normal equine pituitary gland dimensions.
Animals—25 adult horses with no clinical signs of
Procedure—Transverse CT images and gross transverse
tissue sections were compared in 2 horses.
Contrast-enhanced CT of the pituitary gland region
was performed postmortem in 23 horses with 4 slice
thickness and interval settings (10-mm contiguous or
overlapping slices and 4-mm contiguous or overlapping
slices). Gross and CT estimates of pituitary gland
dimensions were compared via ANOVA. Accuracy of
CT estimates was calculated with gross pituitary
gland measurements as the known value.
Results—Pituitary glands were located between the
temporomandibular joints and had contrast enhancement.
Mean gross dimensions were length, 2.11 cm;
width, 2.16 cm; height, 0.98 cm; and volume, 2.66
cm3. Gross measurements and CT estimates of pituitary
gland length from 10-mm contiguous and overlapping
slices did not differ. Gross measurements and
CT estimates of pituitary gland width from 4-mm contiguous
and overlapping slices did not differ. Estimates
of height and volume from all CT techniques differed
from gross measurements. Accuracies for CT estimates
were length, 88 to 99%; width, 81 to 92%;
height, 58 to 71%; and volume, 43 to 55%.
Conclusions and Clinical Relevance—Accuracy of
estimates of pituitary gland dimension in horses varied
with CT scanning technique; via CT, estimates of
length and width of glands were more accurate than
estimates of height or volume. (Am J Vet Res 2003;64:1387–1394)
Objective—To assess the potential of adipose-derived nucleated cell (ADNC) fractions to improve tendon repair in horses with collagenase-induced tendinitis.
Procedures—Collagenase was used to induce tendinitis in the superficial digital flexor tendon of 1 forelimb in each horse. Four horses were treated by injection of autogenous ADNC fractions, and 4 control horses were injected with PBS solution. Healing was compared by weekly ultrasonographic evaluation. Horses were euthanatized at 6 weeks. Gross and histologic evaluation of tendon structure, fiber alignment, and collagen typing were used to define tendon architecture. Biochemical and molecular analyses of collagen, DNA, and proteoglycan and gene expression of collagen type I and type III, decorin, cartilage oligomeric matrix protein (COMP), and insulin-like growth factor-I were performed.
Results—Ultrasonography revealed no difference in rate or quality of repair between groups. Histologic evaluation revealed a significant improvement in tendon fiber architecture; reductions in vascularity, inflammatory cell infiltrate, and collagen type III formation; and improvements in tendon fiber density and alignment in ADNC-treated tendons. Repair sites did not differ in DNA, proteoglycan, or total collagen content. Gene expression of collagen type I and type III in treated and control tendons were similar. Gene expression of COMP was significantly increased in ADNC-injected tendons.
Conclusions and Clinical Relevance—ADNC injection improved tendon organization in treated tendons. Although biochemical and molecular differences were less profound, tendons appeared architecturally improved after ADNC injection, which was corroborated by improved tendon COMP expression. Use of ADNC in horses with tendinitis appears warranted.
Objective—To determine whether antibodies against
Sarcocystis neurona could be detected in CSF from
clinically normal neonatal (2 to 7 days old) and young
(2 to 3 months old) foals.
Animals—15 clinically normal neonatal Thoroughbred
Procedure—Serum and CSF samples were obtained
from foals at 2 to 7 days of age and tested for antibodies
against S neurona by means of western blotting.
Serum samples from the mares were also tested
for antibodies against S neurona. Additional CSF
and blood samples were obtained from 5 foals
between 13 and 41 days after birth and between 62
and 90 days after birth.
Results—Antibodies against S neurona were detected
in serum from 13 mares and their foals; antibodies
against S neurona were detected in CSF from 12 of
these 13 foals. Degree of immunoreactivity in serum
and CSF decreased over time, and antibodies against
S neurona were no longer detected in CSF from 2
foals 83 and 84 days after birth. However, antibodies
could still be detected in CSF from the other 3 foals
between 62 and 90 days after birth.
Conclusions and Clinical Relevance—Results indicate
that antibodies against S neurona can be detected
in CSF from clinically normal neonatal (2 to 7 days
old) foals born to seropositive mares. This suggests
that western blotting of CSF cannot be reliably used
to diagnose equine protozoal myeloencephalitis in
foals < 3 months of age born to seropositive mares.
(J Am Vet Med Assoc 2002;220:208–211)