Toxicity in Doberman Pinchers with ventricular arrhythmias treated with amiodarone (1996-2005).
BACKGROUND
Asymptomatic Doberman Pinschers with dilated cardiomyopathy (DCM) often die suddenly owing to ventricular tachycardia that degenerates into ventricular fibrillation. A safe and effective antiarrhythmic drug treatment is needed. This will require a large, well-controlled, prospective study.


OBJECTIVE
Amiodarone toxicity is common in Dobermans with occult DCM and ventricular tachyarrhythmias refractory to antiarrhythmia therapy. Infrequent monitoring of hepatic function is inadequate. Frequent monitoring may be useful to determine dogs in which the dosage should be decreased or the drug withdrawn.


METHODS
Medical records from the University of Georgia and Cornell University were searched for Doberman Pinschers diagnosed with preclinical DCM that received amiodarone for severe ventricular arrhythmias refractory to other antiarrhythmic agents. Echocardiographic data, Holter recording data, hepatic enzyme serum activity, and serum amiodarone concentrations were recorded. The presence of clinical signs of toxicity was recorded. Serum amiodarone concentrations were obtained in some dogs.


RESULTS
Reversible toxicity was identified in 10 of 22 (45%) dogs.


CONCLUSIONS
Adverse effects from amiodarone were common and were, in part, dosage related. Patients should be monitored for signs of toxicity and liver enzyme activity should be measured at least monthly.
Kraus
M S
MS
Department of Small Animal Medicine and Surgery, University of Georgia, Athens, GA, USA. msk16@cornell.edu
Thomason
J D
JD
Fallaw
T L
TL
Calvert
C A
CA
D000638:Amiodarone / Q000008:administration & dosage / Q000009:adverse effects* / Q000627:therapeutic use; D000818:Animals; D000889:Anti-Arrhythmia Agents / Q000008:administration & dosage / Q000009:adverse effects* / Q000627:therapeutic use; D002311:Cardiomyopathy, Dilated / Q000188:drug therapy / Q000662:veterinary*; D056486:Chemical and Drug Induced Liver Injury; D004283:Dog Diseases / Q000139:chemically induced / Q000188:drug therapy*; D004285:Dogs; D004305:Dose-Response Relationship, Drug; D005260:Female; D008107:Liver Diseases / Q000662:veterinary; D008297:Male; D012189:Retrospective Studies; D017180:Tachycardia, Ventricular / Q000188:drug therapy / Q000662:veterinary*
D000889:Anti-Arrhythmia Agents; D000638:Amiodarone