Objective—To determine clinical features of dilated
cardiomyopathy (DCM) in Great Danes and to determine
whether DCM is familial in this breed.
Animals—17 Great Danes with DCM.
Procedure—Medical records of Great Danes in which
DCM was diagnosed on the basis of results of
echocardiography (fractional shortening < 25%, endsystolic
volume index > 30 ml/m2 of body surface
area) were reviewed. Pedigrees were obtained for
affected animals, as well as for other Great Danes in
which DCM had been diagnosed.
Results—Dilated cardiomyopathy appeared to be
familial and was characterized by ventricular dilatation,
congestive heart failure (left-sided or biventricular),
and atrial fibrillation. Pedigree analysis suggested
that DCM was inherited as an X-linked recessive trait,
but the mode of inheritance could not be definitively
Conclusions and Clinical Relevance—Results suggest
that DCM may be an X-linked recessive trait in
Great Danes. Thus, dogs with DCM probably should
not be used for breeding, and female offspring of
affected dogs should be used cautiously. Male offspring
of affected females are at an increased risk of
developing DCM and should be evaluated periodically
for early signs of disease. Results of pedigree
analysis were preliminary and should be used only
as a guide for counseling breeders, rather than as a
basis for making breeding decisions. (J Am Vet Med
Objective—To evaluate the use of 24-hour ambulatory
electrocardiography (AECG) for the detection of ventricular
premature complexes (VPC) in healthy dogs.
Animals—50 healthy mature dogs.
Procedure—A 24-hour AECG was performed on each
dog and evaluated for the presence of VPC.
Results—Fifty dogs weighing between 18.2 to 40.9 kg
(40 and 90 lb) representing 13 breeds were evaluated;
there were 4 sexually intact females, 21 spayed
females, 4 sexually intact males, and 21 castrated
males. Ages ranged from 1 to 12 years. Thirty-four dogs
had no VPC; 16 dogs had between 1 and 24 VPC. The
grade of arrhythmia ranged from 1 to 4, with 4 dogs
having an arrhythmia with a grade > 1. Significant differences
were not detected between the group of
dogs with VPC and those without VPC with regard to
sex, age, and minimum, maximum, or mean heart rate.
Conclusions and Clinical Relevance—We conclude
that healthy mature dogs have infrequent VPC, as
detected by use of 24-hour AECG. The presence of
numerous or sequential VPC may be suggestive of
cardiac or systemic disease and may indicate the
need for thorough clinical evaluation. (J Am Vet Med
Objective—To evaluate the use of in-hospital electrocardiography
(ECG) for detection of ventricular premature
complexes (VPC), compared with 24-hour
Animals—188 Boxers > 9 months old; 31 had a history
of syncope, and 157 were healthy (no history of
Procedure—In-hospital ECG was performed on all
Boxers for at least 2 minutes. Within 7 days after the
in-hospital ECG was completed, 24-hour ambulatory
ECG was performed.
Results—The specificity of in-hospital ECG was
100% for the detection of at least 50 VPC in a 24-hour
period in dogs with syncope and 93% in healthy dogs.
In-hospital ECG had poor sensitivity, although sensitivity
increased as the number of VPC per 24 hours
Conclusions and Clinical Relevance—Use of in-hospital
ECG is highly specific for detection of at least 50
VPC during a 24-hour period. However, in-hospital
ECG is insensitive, and a lack of VPC does not suggest
that the dog does not have a substantial number
of VPC during that same period. The use of in-hospital
ECG appears to be inadequate for screening purposes
and therapeutic evaluations in mature Boxers with
ventricular arrhythmic disease. (J Am Vet Med Assoc
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 evaluate the effect of 4 antiarrhythmic
treatment protocols on number of ventricular premature
complexes (VPC), severity of arrhythmia, heart
rate (HR), and number of syncopal episodes in Boxers
with ventricular tachyarrhythmias.
Design—Randomized controlled clinical trial.
Procedure—Dogs with > 500 VPC/24 h via 24-hour
ambulatory ECG (AECG) were treated with atenolol
(n = 11), procainamide (11), sotalol (16), or mexiletine
and atenolol (11) for 21 to 28 days. Results of pre- and
posttreatment AECG were compared with regard to
number of VPC/24 h; maximum, mean, and minimum
HR; severity of arrhythmia; and occurrence of syncope.
Results—Significant differences between pre- and
posttreatment number of VPC, severity of arrhythmia,
HR variables, or occurrence of syncope were not
observed in dogs treated with atenolol or procainamide.
Significant reductions in number of VPC,
severity of arrythmia, and maximum and mean HR
were observed in dogs treated with mexiletineatenolol
or sotalol; occurrence of syncope was not significantly
different between these 2 treatment groups.
Conclusions and Clinical Relevance—Treatment
with sotalol or mexiletine-atenolol was well tolerated
and efficacious. Treatment with procainamide or
atenolol was not effective. (J Am Vet Med Assoc 2002;221:522–527)