Objective—To determine effects of tricyclic antidepressants
(TCA) on the ECG of dogs treated for
behavioral conditions and to examine correlations
between ECG findings and serum concentrations of
Animals—39 client-owned dogs with behavioral
Procedure—Two groups of dogs with behavioral
problems were evaluated. In group 1 (n = 20), ECG
tracings were recorded before starting treatment
with TCA and again after treatment for ≥ 1 month.
Dogs in group 2 were already on long-term maintenance
amounts of antianxiety medication when ECG
tracings were recorded and serum concentrations of
medications were obtained.
Results—Significant differences were not detected
for dogs in group 1 between ECG values measured
before and after TCA administration. The ECG values
for dogs in group 2 did not differ significantly from the
mean of group-1 dogs before receiving medication or
from the reference range used at our facility. Duration
of the P wave had a significant positive correlation
with serum concentrations of clomipramine but significant
negative correlation with serum concentrations
of amitriptyline. The QT interval corrected for
heart rate had a significant negative correlation with
serum concentrations of amitriptyline.
Conclusion and Clinical Relevance—Amitriptyline
and clomipramine administered at standard dosages
apparently do not cause ECG abnormalities in
healthy dogs with behavioral problems. These medications
should be used cautiously in dogs with conduction
abnormalities, and clinicians should periodically
monitor ECG and use good clinical judgment to
weigh risks and benefits of medications for the safety
of each dog. (J Am Vet Med Assoc 2000;216:
Objective—To characterize sleeping respiratory rates (SRRs) and resting respiratory rates (RRRs), collected in the home environment, of dogs with subclinical heart disease that could result in left-sided congestive heart failure.
Design—Prospective cross-sectional study.
Animals—190 adult dogs with subclinical left-sided heart disease.
Procedures—Most dogs had mitral valve disease or dilated cardiomyopathy of various severities. Clients collected ten 1-minute SRRs or RRRs during a period ranging from 1 week to 6 months. Clinicians provided echocardiographic and medical data on each patient.
Results—The within-dog mean SRR (SRRmean; 16 breaths/min) was significantly lower than the within-dog mean RRR (RRRmean; 21 breaths/min). Seven dogs had SRRmean and 33 dogs had RRRmean > 25 breaths/min; 1 dog had SRRmean and 12 dogs had RRRmean > 30 breaths/min; these dogs mostly had a left atrial (LA)-to-aortic ratio > 1.8. Dogs with moderate LA enlargement had a significantly higher SRRmean than did other dogs. However, median SRRmean for each of 4 levels of LA enlargement was < 20 breaths/min; median RRRmean for each of 4 levels of LA enlargement was < 25 breaths/min. Both within-dog SRR and RRR remained stable for 10 consecutive measurements. Treatment with cardiac medications or presence of pulmonary hypertension was not associated with SRRmean or RRRmean.
Conclusions and Clinical Relevance—Results suggested that dogs with confirmed subclinical left-sided heart disease of various severities generally had SRRmean < 25 breaths/min, which was infrequently exceeded at any time, and that SRR and RRR remained stable, regardless of individual within-dog SRRmean or RRRmean. (J Am Vet Med Assoc 2013;243:839–843)