Objective—To determine whether platelet clumps
are homogeneously distributed in blood samples, and
whether platelet concentrations (PC) obtained by use
of impedance and buffy coat analysis can be considered
minimum values when platelet clumps are present.
Sample Population—50 blood samples obtained
from 30 dogs.
Procedure—10 blood samples containing platelet
clumps were used and 10 smears were made from
each sample; amount of platelet clumping was graded
for all 100 smears. Blood from each of 20 healthy
dogs was divided between 2 EDTA tubes before and
after platelet clumping was induced by adenosine
diphosphate (ADP). The PC for each ADP-treated and
untreated sample were measured, using impedance
and quantitative buffy coat analyzers.
Results—Platelet clumps were evident in all 100
blood smears, but the amount of clumping varied considerably
within some samples. Using the impedance
analyzer, the PC of ADP-treated samples were significantly
lower and never higher than the PC of untreated
samples. Using the buffy coat analyzer, some ADPtreated
samples had increased PC; however, significant
differences were not detected between treated
and untreated samples.
Conclusions and Clinical Relevance—Platelet
clumping was not homogeneous within blood samples.
When platelet clumps were identified by direct
examination of blood smears, the PC detected by use
of the impedance analyzer could be considered minimum
values. In contrast, the PC detected by use of
the buffy coat analyzer were sometimes increased.
Useful information can be obtained by measuring PC
in blood with platelet clumps; values obtained by use
of impedance can be considered minimums, and values
obtained by use of buffy coat analysis may be
either minimum values or reasonable estimates of
PC. (J Am Vet Med Assoc 2001;219:1552–1556)
Objective—To determine the prevalence of ventricular arrhythmias in clinically normal adult Boxers.
Design—Prospective cross-sectional study.
Animals—301 Boxers (181 females and 120 males) > 1 year old with echocardiographically normal systolic function and no history of syncope or congestive heart failure.
Procedures—Physical examination, which included echocardiography, was performed on all dogs. A 24-hour ambulatory ECG was performed on each dog, and results were evaluated to assess ventricular arrhythmias. Statistical evaluation was performed to determine correlations between the total number of ventricular premature complexes (VPCs)/24 h, grade of ventricular arrhythmia, and age of the dogs.
Results—Age of dogs ranged from 1 to 16 years (median, 4 years). Number of VPCs/24 h in each dog ranged from 0 to 62,622 (median, 6 VPCs/24 h). Grade of arrhythmias ranged from 0 to 3 (median, 1). Age was correlated significantly with number of VPCs/24 h (r = 0.43) and with grade of arrhythmia (r = 0.37). Number of VPCs/24 h was significantly correlated with grade of arrhythmia (r = 0.82).
Conclusions and Clinical Relevance—Clinically normal adult Boxers generally had < 91 VPCs/24 h and an arrhythmia grade < 2. Boxers with > 91 VPCs/24 h were uncommon and may have represented dogs with arrhythmogenic right ventricular cardiomyopathy or other disease processes that could have resulted in the development of ventricular arrhythmias.
Objective—To determine aortic ejection velocity in
healthy adult Boxers with soft ejection murmurs without
overt structural evidence of left ventricular outflow
tract obstruction and in healthy Boxers without
Procedure—Dogs were examined independently by
2 individuals for evidence of a cardiac murmur, and a
murmur grade was assigned. Maximal instantaneous
(peak) aortic ejection velocity was measured by
means of continuous-wave Doppler echocardiography
from a subcostal location. Forty-eight dogs were
reexamined approximately 1 year later.
Results—A soft (grade 1, 2, or 3) left-basilar ejection
murmur was detected in 113 (56%) dogs. Overall
median aortic ejection velocity was 1.91 m/s (range,
1.31 to 4.02 m/s). Dogs with murmurs had significantly
higher aortic ejection velocities than did those
without murmurs (median, 2.11 and 1.72 m/s, respectively).
Auscultation of a murmur was 87% sensitive
and 66% specific for the identification of aortic ejection
velocity > 2.0 m/s. An ejection murmur and aortic
ejection velocity > 2.0 m/s were identified in 73
(36%) dogs. For most dogs, observed changes in
murmur grade and aortic ejection velocity during a follow-up examination 1 year later were not clinically
Conclusions and Clinical Relevance—Results
suggested that ejection murmurs were common
among healthy adult Boxers and that Boxers with
murmurs were likely to have high (> 2.0 m/s) aortic
ejection velocities. The cause of the murmurs in
these dogs is unknown. (J Am Vet Med Assoc
Objective—To identify clinical, echocardiographic,
and electrocardiographic abnormalities in Boxers with
cardiomyopathy and echocardiographic evidence of
left ventricular systolic dysfunction.
Animals—48 mature Boxers.
Procedure—Medical records were reviewed for information
on age; sex; physical examination findings;
and results of electrocardiography, 24-hour ambulatory
electrocardiography, thoracic radiography, and
Results—Mean age of the dogs was 6 years (range, 1
to 11 years). Twenty (42%) dogs had a systolic murmur,
and 9 (19%) had ascites. Congestive heart failure was
diagnosed in 24 (50%) dogs. Seventeen (35%) dogs
had a history of syncope. Mean fractional shortening
was 14.4% (range, 1% to 23%). Mean left ventricular
systolic and diastolic diameters were 4.5 cm (range, 3
to 6.3 cm) and 5.3 cm (range, 3.9 to 7.4 cm), respectively.
Twenty-eight (58%) dogs had a sinus rhythm
with ventricular premature complexes (VPCs), and 20
had supraventricular arrhythmias (15 with atrial fibrillation
and 5 with sinus rhythm and atrial premature complexes).
Sixteen of the dogs with supraventricular
arrhythmias also had occasional VPCs. Morphology of
the VPCs seen on lead II ECGs was consistent with left
bundle branch block in 25 dogs, right bundle branch
block in 8, and both in 11.
Conclusions and Clinical Relevance—Results suggest
that Boxers with cardiomyopathy and left ventricular
dysfunction frequently have arrhythmias of supraventricular
or ventricular origin. Whether ventricular dysfunction
was preceded by electrical disturbances could
not be determined from these data, and the natural history
of myocardial disease in Boxers requires further
study. (J Am Vet Med Assoc 2005;226:1102–1104)