Objective—To evaluate the usefulness of multisite
quantitative ultrasonography for noninvasive assessment
of bone in horses.
Sample Population—12 healthy horses and both
forelimbs from 8 clinically normal horses.
Procedure—For in vivo measurements, various
regions of interest (ROI) were examined on the third
metacarpal bone, radius, and tibia. Precision error for
speed of sound (SOS) measurements was obtained
by measuring each ROI of 4 horses 10 times with
probe repositioning. Additionally, 3 operators measured
each aspect of the third metacarpal bone of 6
horses 5 times each. For ex vivo measurements, third
metacarpal bones were examined at 9 ROI, and SOS
measurements were performed before and after soft
tissue removal. One ROI of a single forelimb was subjected
to 96 ex vivo measurements with 3 different
Results—The lateral aspect of the third metacarpal
bone had significantly higher SOS values than the dorsal
and medial aspect of the third metacarpal bone.
No difference was obtained between SOS values of
the lateral and medial aspect of the radius. The tibia
had significantly higher SOS values than the lateral
aspect of the radius and the dorsal and medial aspect
of the third metacarpal bone. Intraoperator coefficients
of variation ranged from 0.62 to 3.15%, and
interoperator coefficients of variation ranged from
0.78 to 2.70%. Values of SOS were highest when silicone
oil was used as the contact medium.
Conclusions and Clinical Relevance—Speed of
sound measurements obtained by quantitative ultrasonography
in axial transmission mode can be used
to precisely measure superficial cortical bone properties
of third metacarpal bone, radius, and tibia in horses.
(Am J Vet Res 2002;63:1464–1469)
Objective—To evaluate a human assay for quantification
of carboxy-terminal cross-linking telopeptide of
type I collagen (CTX-I), assess the influence of age on
plasma CTX-I concentration, investigate the relationship
between plasma CTX-I and serum osteocalcin
concentrations, and determine whether concentrations
of plasma CTX-I or serum osteocalcin fluctuate
in circadian manner in horses.
Horses—75 clinically normal horses.
Procedure—Cross-reactivity between equine serum
CTX-I and CTX-I antibodies in an automated electrochemiluminescent
sandwich antibody assay (ECLIA)
was evaluated via a specificity test (ie, dilution test) and
recovery calculation. Serum osteocalcin concentration
was measured with an equine-specific osteocalcin
radioimmunoassay. To analyze diurnal variations in plasma
CTX-I and serum osteocalcin concentrations, blood
samples were obtained hourly during a 24-hour period.
Results—Results of the dilution test indicated good
correlation ( r > 0.99) between expected serum CTX-I
concentrations and measured serum CTX-I concentrations.
The calculated CTX-I recovery was 97.6% to
109.9%. Plasma CTX-I and serum osteocalcin concentrations
were correlated. Plasma CTX-I concentration
was inversely correlated with age of the horse.
No significant circadian variations in plasma CTX-I and
serum osteocalcin concentrations were detected.
Conclusions and Clinical Relevance—Results suggest
that the fully automated CTX-I ECLIA can be
used for evaluation of plasma and serum samples
from horses and may be a useful tool to monitor bone
metabolism changes. Horses in this study did not
have notable diurnal fluctuations in serum osteocalcin
and plasma CTX-I concentrations. ( Am J Vet Res 2004;65:104–109)
Objective—To determine whether dobutamine stress
tests (DST) can be used to detect cardiac dysfunction
in dogs with early left ventricular dysfunction (ELVD)
induced by rapid right ventricular pacing (RRVP).
Animals—7 adult male Beagles.
Procedure—A pacemaker was surgically implanted
in each dog at the level of the right ventricular apex.
Electrocardiography, Doppler sphygmomanometry,
and Doppler echocardiography were performed
before and during a DST prior to activation of the
pacemaker and every 3 to 4 days during the period of
RRVP. Dobutamine stress tests were performed by
infusing dobutamine at incremental dosages ranging
from 12.5 to 42.5 µg/kg of body weight/min.
Results—Clinical signs of congestive heart failure
were not observed during the pacing period. However,
all dogs developed ELVD associated with significant
changes in values for most Doppler echocardiographic
variables obtained prior to DST. Adverse cardiac
effects were not detected during DST. Most Doppler
echocardiographic indices of cardiac function were significantly
altered in response to dobutamine infusion
during the pacing period, compared with prepacing values.
However, a dobutamine-induced 2-fold increase
in cardiac output was maintained.
Conclusions and Clinical Relevance—Dobutamine
stress tests can be safely performed in dogs with
experimentally induced ELVD. Dobutamine stress
tests may be a sensitive, noninvasive diagnostic
method, complementary to standard clinical examinations,
for detection of early cardiac dysfunction in
dogs asymptomatic for dilated cardiomyopathy. (Am J
Vet Res 2001;62:448–455)