This feature is sponsored by the American College of Veterinary Behaviorists. Readers of the JAVMA are invited to submit reports, which should include a brief description of a behavioral problem, the evaluation and treatment, and succinct discussion of the case.
Send contributions to Dr. Bonnie Beaver, Department of Small Animal Medicine and Surgery, College of Veterinary Medicine, Texas A&M University, College Station, TX 77843-4474.
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: