Electrocardiographic assessment of antianxiety medication in dogs and correlation with serum drug concentration.
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 these medications.


METHODS
Repeated-measures study.


METHODS
39 client-owned dogs with behavioral problems.


METHODS
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 > or = 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.


CONCLUSIONS
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.
Reich
M R
MR
Department of Clinical Studies, School of Veterinary Medicine, University of Pennsylvania, Philadelphia 19104-6010, USA.
Ohad
D G
DG
Overall
K L
KL
Dunham
A E
AE
D000639:Amitriptyline / Q000009:adverse effects / Q000097:blood / Q000627:therapeutic use; D000818:Animals; D000929:Antidepressive Agents, Tricyclic / Q000009:adverse effects* / Q000097:blood / Q000627:therapeutic use; D001522:Behavior, Animal / Q000187:drug effects*; D002997:Clomipramine / Q000009:adverse effects / Q000097:blood / Q000627:therapeutic use; D004283:Dog Diseases / Q000188:drug therapy* / Q000503:physiopathology; D004285:Dogs; D004562:Electrocardiography / Q000187:drug effects / Q000662:veterinary*; D016231:Fluorescence Polarization Immunoassay / Q000662:veterinary; D018709:Statistics, Nonparametric
D000929:Antidepressive Agents, Tricyclic; D000639:Amitriptyline; D002997:Clomipramine