Objectives—To quantify direction and velocity of
blood flow in hepatic veins in dogs under different
hemodynamic conditions by use of pulsed-wave
Animals—10 healthy dogs.
Procedure—Dogs were anesthetized, and venous
flow velocities in the quadrate lobe were measured.
Arterial blood pressure, right atrial pressure,
pulmonary artery pressure, and cardiac output
were measured simultaneously. The timing of each
waveform during the cardiac cycle was used to
identify velocity profiles. Peak waveform velocities
were measured during conditions of light anesthesia
with isoflurane (baseline; period 1), cardiovascular
depression following administration of highdose
isoflurane and esmolol IV (period 2), cardiovascular
depression with crystalloid volume expansion
(period 3), and high cardiac output induced
with dobutamine (period 4). Hemodynamic measurements
and maximum waveform velocities
were compared among the 4 periods by use of an
ANOVA and univariate and multivariate linear
Results—During each study period, 4 distinct, lowvelocity
waves were identified. Mean velocities
recorded during period 1 were as follows: retrograde
atrial contraction a-wave, 7.3 cm/s; antegrade systolic
S-wave, 15.0 cm/s; retrograde venous return v-wave,
2.7 cm/s; and antegrade diastolic D-wave, 11.4 cm/s.
Mean S:D ratio was 1.27. During periods 3 and 4, Swave
velocity increased; D-wave velocity was highest
during period 4.
Conclusions and Clinical Relevance—Consistent
hepatic venous velocity profiles were observed in
healthy dogs under different hemodynamic conditions.
These findings provide baseline values that may
be useful in evaluating clinical cases, but further study
involving healthy, awake dogs and dogs with cardiac
and hepatic diseases is required. (Am J Vet Res
Objective—To quantitatively determine echogenicity
of the liver and renal cortex in clinically normal cats.
Animals—17 clinically normal adult cats.
Procedure—3 ultrasonographic images of the liver and
the right kidney were digitized from video output from
each cat. Without changing the ultrasound machine
settings, an image of a tissue-equivalent phantom was
digitized. Biopsy specimens of the right renal cortex
and liver were obtained for histologic examination.
Mean pixel intensities within the region of interest
(ROI) on hepatic, renal cortical, and tissue-equivalent
phantom ultrasonographic images were determined by
histogram analysis. From ultrasonographic images,
mean pixel intensities for hepatic and renal cortical ROI
were standardized by dividing each mean value by the
mean pixel intensity from the tissue-equivalent phantom.
Results—The mean (± SD) standardized hepatic
echogenicity value was 1.06 ± 0.02 (95% confidence
interval, 1.02 to 1.10). The mean standardized right
renal cortical echogenicity value was 1.04 ± 0.02
(95% confidence interval, 1.01 to 1.08). The mean
combined standardized hepatic and renal cortical
echogenicity value was 1.02 ± 0.05 (95% confidence
interval, 0.99 to 1.04).
Conclusions and Clinical Relevance—Quantitative
determination of hepatic and renal cortical echogenicity
in cats is feasible, using histogram analysis, and
may be useful for early detection of diffuse parenchymal
disease and for serially evaluating disease progression.
(Am J Vet Res 2000;61:1016–1020)
Objective—To determine maximum extrarenal plasma
clearance of technetium-99m-mercaptoacetyltriglycine
(99mTc–MAG3) and maximum extrarenal
hepatic uptake of 99mTc–MAG3 in cats.
Animals—6 clinically normal adult cats.
Procedure—Simultaneously, baseline plasma clearance
and camera-based uptake of 99mTc–MAG3 were
determined in anesthetized cats. Double exponential
curves were fitted to plasma clearance data. Injected
dose was divided by area under the curve and body
weight to determine 99mTc–MAG3 clearance. Regions
of interest were drawn around kidneys and liver, and
percentage dose uptake was determined 1 to 3 minutes
after injection. After bilateral nephrectomy,
simultaneous extrarenal plasma clearance and camera-
based hepatic uptake of 99mTc–MAG3 were evaluated
in each cat.
Results—Mean ± SD baseline plasma clearance and
extrarenal clearance were 5.29 ± 0.77 and 0.84 ± 0.47
mL/min/kg, respectively. Mean extrarenal clearance
(as a percentage of baseline plasma clearance) was
16.06 ± 7.64%. For right, left, and both kidneys, mean
percentage dose uptake was 9.42 ± 2.58, 9.37 ± 0.86,
and 18.79 ± 2.47%, respectively. Mean hepatic percentage
dose uptake before and after nephrectomy
was 12.95 ± 0.93 and 21.47 ± 2.00%, respectively.
Mean percentage change of hepatic uptake after
nephrectomy was 166.89 ± 23.19%.
Conclusions and Clinical Relevance—In cats,
extrarenal clearance of 99mTc–MAG3 is higher than that
of other species; therefore, 99mTc–MAG3 is not useful
for estimation of renal function in felids. Evaluation of
renal function in cats may be more accurate via camera-
based versus plasma clearance-based methods
because camera-based studies can discriminate specific
organs. (Am J Vet Res 2003;64:1076–1080)