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 evaluate nonselective computed
tomographic (CT) venography for evaluating the cervical
internal vertebral venous plexus (IVVP), define the
diameter and area dimensions of the IVVP, and determine
the relationship between dimensions of the cervical
IVVP and other vertebral components in medium-sized dogs.
Animals—6 healthy dogs that weighed 18 to 27 kg.
Procedure—Helical CT scans were performed from
C1 to C7 before and after IV injection of contrast medium
(480 mg of iodine/kg) and a continuous infusion
(240 mg of iodine/kg). Image data were transferred to
a CT workstation, and measurements were performed
on displayed transverse images. Diameter and area
measurements of the vertebral canal, dural sac, IVVP,
and vertebral body were obtained at C3 to C7.
Results—Opacification of vertebral venous structures
was achieved in all dogs with no adverse reactions.
Sagittal diameters of the IVVP for C3 to C7 ranged
from 0.6 to 3.2 mm. Transverse diameters ranged
from 2.32 to 5.74 mm. The IVVP area represented
12.4% of the mean vertebral canal transverse area
and 30.61% of the mean vertebral epidural space
area. Area measurements of the IVVP were significantly
correlated with vertebral canal area and dural
Conclusions and Clinical Relevance—Results indicated
that nonselective CT venography is a safe, sensitive
method for performing morphometric assessments
of the cervical IVVP in dogs. Findings support
the theory that there may be a physiologic or developmental
relationship between cervical vertebral canal
components. (Am J Vet Res 2005;66:2039–2045)