Objective—To study the hemodynamic effects of
marbofloxacin (MBF) in isoflurane-anesthetized dogs.
Animals—6 healthy 8-month-old Beagles.
Procedure—Anesthesia was induced with sodium
thiopental and maintained with isoflurane.
Cardiovascular variables were monitored throughout
anesthesia. Marbofloxacin was administered by
an IV bolus at 2 mg/kg, followed 10 minutes later by
an infusion at a rate of 40 mg/kg/h for 30 minutes
(total dose, 20 mg/kg). Plasma MBF concentrations
were measured by high-performance liquid
Results—The mean peak concentration during MBF
infusion was 34.2 ± 6.4 µg/mL. The IV administration
of the MBF bolus did not alter any cardiovascular variable
in isoflurane-anesthetized dogs. Significant
changes were found during infusion when a cumulative
dose of 12 mg/kg had been given. The maximal
decreases observed at the end of the infusion were
16% in heart rate, 26% in systolic left ventricular pressure,
33% in systolic aortic pressure, 38% in diastolic
aortic pressure, 29% in cardiac output, and 12% in
QT interval. All dogs recovered rapidly from anesthesia
at the end of the experiment.
Conclusions and Clinical Relevance—MBF may
safely be used at 2 mg/kg IV in isoflurane-anesthetized
dogs, and significant adverse cardiovascular effects
are found only when 6 to 8 times the recommended
dose is given. (Am J Vet Res 2005;66:2090–2094)
Objective—To assess the effects of moderate exercise
on plasma creatine kinase (CK) pharmacokinetics
and to estimate exercise-induced muscle damage in
Animals—6 untrained adult Beagles.
Procedure—The study was divided into 3 phases. In
phase 1, dogs ran for 1 hour at a speed of 9 km/h, and
samples were used to determine the area under the
plasma CK activity versus time curve (AUC) induced
by exercise. In phases 2 and 3, pharmacokinetics of
CK were calculated in dogs during exercise and at
rest, respectively. Values for AUC and plasma clearance
(Cl) were used to estimate muscle damage.
Results—At rest, values for Cl, steady-state volume
of distribution (Vdss), and mean retention time (MRT)
were 0.32 ± 0.02 ml/kg of body weight/min, 57 ± 17.3
ml/kg, and 3.0 ± 0.57 h, respectively. During exercise,
Cl decreased significantly (0.26 ± 0.03 ml/kg/min),
MRT increased significantly, (4.4 ± 0.97 h), and Vdss
remained unchanged. Peak of plasma CK activity (151
± 58.8 U/L) was observed 3 hours after completion of
exercise. Estimated equivalent amount of muscle corresponding
to the quantity of CK released was 41 ±
Conclusion and Clinical Relevance—These results
revealed that exercise had a minor effect on CK disposition
and that the equivalent amount of muscle
damaged by moderate exercise was negligible. This
study illustrates the relevance for use of the minimally
invasive and quantitative pharmacokinetic approach
when estimating muscle damage. (Am J Vet Res
Objectives—To investigate and validate noninvasive
methods for the quantitative evaluation of postinjection
Animals—5 adult sheep.
Procedures—Muscle lesions were induced twice in
the lumbar region of the longissimus dorsi muscles (2
sides) by IM administration of a 20% formulation of
long-acting oxytetracycline (20 mg/kg of body
weight). Clinical signs and local cutaneous temperature
above the injection site were recorded. Muscle
lesions were quantitatively evaluated by ultrasonography
and by use of pharmacokinetic analysis of plasma
creatine kinase activity, and both were compared with
a comprehensive planimetric computer-assisted
analysis of the injection sites after euthanasia.
Results—Transient cutaneous hypothermia (temperature
change, –3.9 ± 0.62 C) and subsequent persistent
hyperthermia (3.1 ± 1.35 C) were observed after the
administrations. Despite coefficient of variation < 10%
for precision of ultrasonographic measurement of normal
muscle, measurements of the lesions, with coefficient
of variation > 60% for precision, were systematically
underestimated. Quantitative evaluation of muscle
damage by use of pharmacokinetic analysis of creatine
kinase (12.1 ± 4.96 g) was in agreement with results of
macroscopic planimetric evaluation (10.8 ± 3.64 g).
Conclusions and Clinical Relevance—Ultrasonography
cannot be used for quantitative assessment
of postinjection muscle damage. Pharmacokinetic
analysis of creatine kinase provides an accurate
quantitative evaluation of macroscopic muscle
damage after IM administration of drugs. (Am J Vet
Objective—To establish reference intervals of plasma biochemical values in healthy adult domestic shorthair (DSH) cats by use of controlled conditions.
Animals—95 healthy client-owned cats.
Procedures—Food was withheld from the cats overnight. All blood samples were obtained on the same day, at the same location, and by the same investigator. Blood samples were collected from a cephalic vein into lithium heparin tubes. After centrifugation of blood samples, plasma supernatants were harvested and stored at −20°C until assayed for total proteins, albumin, creatinine, urea, glucose, calcium, phosphates, sodium, chloride, potassium, and CO2 concentrations and alkaline phosphatase and alanine aminotransferase activities.
Results—Reference intervals in healthy adult DSH cats were 65 to 85 g/L for total proteins, 27 to 39 g/L for albumin, 89 to 207 μmol/L for creatinine, 6.6 to 11.3 mmol/L for urea, 4.1 to 8.2 mmol/L for glucose, 2.4 to 2.9 mmol/L for calcium, 1.1 to 2.1 mmol/L for phosphates, 153 to 161 mmol/L for sodium, 120 to 127 mmol/L for chloride, 3.3 to 4.2 mmol/L for potassium, 15 to 21 mmol/L for CO2, 32 to 147 U/L for alkaline phosphatase, and 34 to 123 U/L for alanine aminotransferase.
Conclusions and Clinical Relevance—This study provided reference intervals for plasma analytes in adult DSH cats. The influence of potential confounding factors was minimized through use of controlled preanalytic and analytic conditions. However, these results cannot be extrapolated to other feline breeds or used to interpret results from other biochemical analyzers.
Objective—To determine left ventricular free wall
(LVFW) radial and longitudinal myocardial contraction
velocities in healthy dogs via quantitative 2-dimensional
color tissue Doppler imaging (TDI).
Procedure—TDI was used by a single trained observer
to measure radial and longitudinal myocardial
movement in the LVFW. Radial myocardial velocities
were recorded in segments in the endocardial and
epicardial layers of the LVFW, and longitudinal velocities
were recorded in segments at 3 levels (basal,
middle, apical) of the LVFW.
Results—LVFW velocities were higher in the endocardial
layers than in the epicardial layers. Left ventricular
free wall velocities were higher in the basal
segments than in the middle and apical segments.
Radial myocardial velocity gradients, defined as the
difference between endocardial and epicardial velocities,
were (mean ± SD) 2.5 ± 0.8 cm/s, 3.8 ± 1.5 cm/s,
and 2.3 ± 0.9 cm/s in systole, early diastole, and late
diastole, respectively. Longitudinal myocardial velocity
gradients, defined as the difference between basal
and apical velocities, were 5.9 ± 2.2 cm/s, 6.9 ± 2.5
cm/s, and 4.9 ± 1.7 cm/s in systole, early diastole, and
late diastole, respectively. A breed effect was detected
for several systolic and diastolic TDI variables. In all
segments, systolic velocities were independent of
Conclusions and Clinical Relevance—LVFW
myocardial velocities decreased from the endocardium
to the epicardium and from base to apex, thus
revealing intramyocardial radial and longitudinal velocity
gradients. These indices could enhance conventional
echocardiographic analysis of left ventricular
function in dogs. Breed-specific reference intervals
should be defined. (Am J Vet Res 2005;66:953–961)
Objective—To determine the within-day and between-day variability of regurgitant fraction (RF) assessed by use of the proximal isovelocity surface area (PISA) method in awake dogs with degenerative mitral valve disease (MVD), measure RF in dogs with MVD, and assess the correlation between RF and several clinical and Doppler echocardiographic variables.
Animals—6 MVD-affected dogs with no clinical signs and 67 dogs with MVD of differing severity (International Small Animal Cardiac Health Council [ISACHC] classification).
Procedures—The 6 dogs were used to determine the repeatability and reproducibility of the PISA method, and RF was then assessed in 67 dogs of various ISACHC classes. Mitral valve regurgitation was also assessed from the maximum area of regurgitant jet signal-to-left atrium area (ARJ/LAA) ratio determined via color Doppler echocardiographic mapping.
Results—Within- and between-day coefficients of variation of RF were 8% and 11%, respectively. Regurgitation fraction was significantly correlated with ISACHC classification and heart murmur grade and was higher in ISACHC class III dogs (mean ± SD, 72.8 ± 9.5%) than class II (57.9 ± 20.1%) or I (40.7 ± 19.2%) dogs. Regurgitation fraction and left atriumto-aorta ratio, fractional shortening, systolic pulmonary arterial pressure, and ARJ/LAA ratio were significantly correlated.
Conclusions and Clinical Relevance—Results suggested that RF is a repeatable and reproducible variable for noninvasive quantitative evaluation of mitral valve regurgitation in awake dogs. Regurgitation fraction also correlated well with disease severity. It appears that this Doppler echocardiographic index may be useful in longitudinal studies of MVD in dogs.
Objective—To measure the radial and longitudinal
velocities of several myocardial segments of the left
ventricular wall by use of tissue Doppler imaging (TDI)
in healthy cats and determine the repeatability and
reproducibility of the technique.
Animals—6 healthy cats.
Procedure—72 TDI examinations were performed
on 4 days by the same trained observer. Radial parameters
included left endocardial and epicardial
myocardial velocities. Longitudinal parameters
included left basal, middle, and apical myocardial
Results—All velocity profiles had 1 positive systolic
wave (S) and 2 negative diastolic waves (E and A).
Myocardial velocities were higher in the endocardial
than epicardial segments during the entire cardiac
cycle (systolic wave S, 4.4 ± 0.82 and 1.9 ± 0.55; diastolic
wave E, 9.7 ± 1.70 and 2.2 ± 0.74; and diastolic
wave A, 5.1 ± 1.56 and 1.4 ± 0.76, respectively).
Velocities were also higher in the basal than in the apical
segments (systolic wave S, 4.7 ± 0.76 and 0.2 ±
0.11; diastolic wave E, 9.7 ± 1.36 and 0.5 ± 0.17; and
diastolic wave A, 3.7 ± 1.51 and 0.2 ± 0.13, respectively).
The lowest within-day and between-day coefficients
of variation were observed in endocardial segments
(8.2% and 6.5% for systolic wave S and diastolic
wave E, respectively) and in the basal segment in
Conclusions and Clinical Relevance—Repeatability
and reproducibility of TDI were adequate for measurement
of longitudinal and radial left ventricular
motion in healthy awake cats. Validation of TDI is a
prerequisite before this new technique can be recommended
for clinical use. ( Am J Vet Res 2004;
Objective—To evaluate the effects of positioning and
number of repeated measurements on intra- and
interobserver variability of echocardiographic measurements
Animals—4 healthy dogs.
Procedure—Each observer performed 24 examinations,
separately assessing each dog 6 nonconsecutive
times (3 times with the dog in lateral recumbency
and 3 with the dog in a standing position).
Variables evaluated included M-mode measurements
of left ventricular end-diastolic and left ventricular endsystolic
diameters, left ventricular free-wall thickness
in diastole and systole, interventricular septal thickness
in diastole and systole, left ventricular shortening
fraction, and 2-dimensional measurements of the
left atrial diameter-to-aortic diameter ratio.
Results—All coefficients of variation (range, 3.4% to
26.6%) were similar between operators and positions
and were < 15% for 27 of 32 values. For both operators,
repeatability of the measurements was better
for left ventricular end-systolic diameter, left ventricular
free-wall thickness in diastole, left ventricular freewall
thickness in systole, and the left atrial diameterto-
aortic diameter in the standing position, and similar
for both positions for shortening fraction and left ventricular
end-diastolic diameter. No effect of cardiac
cycle was observed.
Conclusions and Clinical Relevance—Within-day
variability of conventional echocardiography performed
with the dog in the standing position was at least as
good as that obtained with the dog in lateral recumbency
for most measured variables. Single measurements
of each variable may be sufficient for trained
observers examining dogs that do not have an arrhythmia.
The standing position should be used, particularly
for stressed or dyspneic dogs. (J Am Vet Med Assoc 2005;227:743–747)
Objective—To determine the intra- and interobserver variability of systolic arterial pressure (SAP) and diastolic arterial pressure (DAP) measurements obtained with 2 indirect methods in awake dogs and percentage of successful measurements.
Animals—6 healthy conscious adult dogs.
Procedures—4 observers with different levels of training measured SAP and DAP on 4 days by use of Doppler ultrasonography (DU) and high-definition oscillometry (HDO). The examinations were randomized. Measurements for each technique were recorded 5 consecutive times, and mean values (total, 720 measurements) were used for statistical analysis.
Results—All within- and between-day coefficients of variation (CVs) for SAP were < 15% irrespective of the observer or method (HDO, 3.6% to 14.1%; DU, 4.1% to 12.4%). Conversely, half the CVs for DAP were > 15% with the highest within- and between-day CVs obtained by the least experienced observer by use of DU (19.5% and 25.9%, respectively). All attempts with HDO were successful, whereas DAP could not be measured by use of DU by the least experienced observer in 17% of attempts.
Conclusions and Clinical Relevance—SAP may be assessed in healthy dogs by use of DU and HDO with good repeatability and reproducibility after a short period of training. Conversely, the variability of DAP is higher and longer training is required to assess DAP via DU than via HDO.
Objective—To determine left ventricular free wall
(LVFW) motions and assess their intra- and interday
variability via tissue Doppler imaging (TDI) in healthy
awake and anesthetized dogs.
Animals—6 healthy adult Beagles.
Procedure—In the first part of the study, 72 TDI
examinations (36 radial and 36 longitudinal) were performed
by the same observer on 4 days during a 2-week period in all dogs. In the second part, 3 dogs
were anesthetized with isoflurane and vecuronium.
Two measurements of each TDI parameter were
made on 2 consecutive cardiac cycles when ventilation
was transiently stopped. The TDI parameters
included maximal systolic, early, and late diastolic
Results—The LVFW velocities were significantly higher
in the endocardial than in the epicardial layers and
also significantly higher in the basal than in the midsegments
in systole, late diastole, and early diastole.
The intraday coefficients of variation (CVs) for systole
were 16.4% and 22%, and the interday CV values were
11.2% and 16.4% in the endocardial and epicardial layers,
respectively. Isoflurane anesthesia significantly
improved the intraday CV but induced a decrease in
LVFW velocities, except late diastolic in endocardial layers
and early diastolic in epicardial layers.
Conclusions and Clinical Relevance—Left ventricular
motion can be adequately quantified in dogs and
can provide new noninvasive indices of myocardial
function. General anesthesia improved repeatability
of the procedure but cannot be recommended
because it induces a decrease in myocardial velocities.
(Am J Vet Res 2004;65:909–915)