Objective—To characterize the salient variables of
the time-domain analysis of heart rate variability
(HRV) in clinically normal Doberman Pinschers and to
compare those variables with those of Doberman
Pinschers with cardiomyopathy and mild to moderate
Animals—46 Doberman Pinschers.
Procedure—HRV was analyzed in the time-domain
from 24-hour Holter recordings obtained from 28
Doberman Pinschers with normal echocardiograms
and 18 Doberman Pinschers with echocardiograms
consistent with mild to moderate myocardial failure.
Results—Significant differences in HRV variables
between the 2 groups of dogs were not detected.
The HRV was greater during the nighttime (12 AM to
6 AM), compared with the 24-hour day and an 18-hour
(6 AM to 12 AM) period.
Conclusions and Clinical Relevance—HRV of dogs
with mild to moderate myocardial failure was not different
from that of clinically normal dogs, because
there were no disturbances of autonomic balance,
baroreceptor function, and other factors that influence
HRV in the dogs with cardiomyopathy, or the
sensitivity of time-domain analysis was overwhelmed
by normal sinus arrhythmia. The techniques now
used to study HRV have important limitations, especially
in dogs, and better noninvasive tests of autonomic
function are needed. ( Am J Vet Res 2000;61:
Objective—To identify, by means of 24-hour ambulatory
electrocardiography, electrocardiographic abnormalities
in overtly healthy Doberman Pinschers in
which results of echocardiography were abnormal.
Design—Clinical case series.
Animals—56 (35 male, 21 female) overtly healthy
Doberman Pinschers with echocardiographic evidence
of cardiomyopathy on initial examination that
subsequently died of cardiomyopathy.
Procedure—Twenty-four-hour ambulatory electrocardiographic
(Holter) recordings obtained at the time of
initial examination were reviewed. For all dogs, scan
quality was > 90%.
Results—Initial Holter recordings of all 56 dogs contained
ventricular premature contractions (VPC).
Thirty-six (65%) dogs had > 1,000 VPC/24 h, 17 (31%)
had > 5,000 VPC/24 h, and 11 (19%) had > 10,000
VPC/24 h. Fifty-four (96%) dogs had couplets of VPC,
37 (66%) had triplets of VPC, and 36 (64%) had
episodes of nonsustained (< 30 seconds) ventricular
tachycardia. Number of VPC/24 h during the initial
Holter recordings was positively correlated with numbers
of couplets and triplets of VPC and number of
ventricular escape beats and negatively correlated
with left ventricular fractional shortening. Twentyeight
dogs died suddenly prior to the putative onset
of congestive heart failure.
Conclusions and Clinical Relevance—Results suggested
that along with echocardiography, 24-hour
ambulatory electrocardiography can be used to help
identify overtly healthy Doberman Pinschers with
cardiomyopathy. (J Am Vet Med Assoc 2000;217:
Objective—To characterize ambulatory electrocardiographic
results of overtly healthy Doberman Pinschers
and determine associations between those results
and development of dilated cardiomyopathy.
Animals—114 (58 male, 56 female) overtly healthy
Doberman Pinschers without echocardiographic evidence
of cardiac disease on initial examination.
Procedure—Echocardiograms and 24-hour ambulatory
electrocardiograms (Holter recordings) were
obtained initially and at variable intervals. The status
(live vs dead) of all dogs was known at least 2 years
and as long as 10 years after initial examination (mean
[± SD] follow-up time, 4.33 ± 1.84 years). Associations
between development of dilated cardiomyopathy and
number of ventricular premature contractions (VPC),
age, and sex were determined.
Results—55 dogs (48%) did not have VPC on initial
Holter recordings, and only 8 dogs had > 50 VPC/24
hours. The likelihood that a dog would have VPC was
associated with increasing age and being male. At
least 1 VPC/24 hours, and in particular, > 50 VPC/24
hours or ≥ 1 couplet or triplet of VPC/24 hours, were
predictive of subsequent development of dilated cardiomyopathy.
Fifty-four dogs (47%) developed dilated
cardiomyopathy; 12 were still alive at the end of the
study, and 42 had died. Twenty-five of these 42 dogs
died after the onset of congestive heart failure (CHF),
15 died suddenly before the onset of overt CHF, and
2 died of noncardiac causes. More males developed
dilated cardiomyopathy than females, and dogs that
died suddenly were approximately 1 year younger
than those that developed CHF.
Conclusions and Clinical Relevance—Results of
high-quality Holter recordings may be used to identify
overtly healthy Doberman Pinschers that are at a high
risk for dilated cardiomyopathy. ( J Am Vet Med Assoc
Objective—To determine effects of the angiotensin
converting enzyme inhibitor benazepril in cats with
induced renal insufficiency.
Procedure—Renal mass was surgically reduced, and
cats were assigned to 1 of 4 eight-cat groups. Group
1 received placebo, whereas groups 2, 3, and 4
received benazepril hydrochloride orally once daily for
approximately 6.5 months at the following doses:
group 2, 0.25 to 0.50 mg/kg of body weight; group 3,
0.50 to 1.00 mg/kg; and group 4, 1.00 to 2.00 mg/kg.
Arterial blood pressures, glomerular filtration rate
(GFR), and renal plasma flow were determined before
treatment and during the treatment period. Other
determinants of renal hemodynamics were measured
by use of micropuncture techniques. Renal biopsy
specimens were examined microscopically.
Results—Compared with cats that received placebo,
mean systolic arterial blood pressure was significantly
less and GFR significantly greater in cats that
received benazepril. Glomerular capillary pressure
and the ratio of efferent to afferent arteriolar vascular
resistance were also significantly less in treated cats.
However, histologic differences in renal specimens
were not detected.
Conclusions and Clinical Relevance—Treatment
with benazepril sustained single nephron GFR in remnant
nephrons of cats with induced renal insufficiency.
Administration of benazepril was also associated
with a small but significant reduction in degree of systemic
hypertension and an increase in whole kidney
GFR. Benazepril may be an effective treatment to
slow the rate of progression of renal failure in cats
with renal disease. (Am J Vet Res 2001;62:375–383)