Management of syncope associated with ventricular premature contractions in a dog

Q: What is the clinical evidence from this study?

Study design: Case Report. Population: Syncope associated with ventricular premature contractions (n=1). Intervention: Sotalol and Mexiletine combination therapy. Primary outcome: Resolution of syncope and ventricular premature contractions (VPCs).

Q: What does this research mean for the field?

Combination therapy with oral sotalol and mexiletine effectively controls ventricular premature contractions and resolves syncope in dogs with left ventricular hypertrophy. Novelty: ClaimNovelty.CONFIRMATORY. Consensus alignment: ConsensusAlignment.NEUTRAL.

Dr; S. Ajithkumar; K. Kavitha.; Anjana Prasad.; S. Kavya.; M.R. Lekshmi

doi:10.51966/jvas.2026.57.2.363-367

June 30, 2026Journal of Veterinary and Animal SciencesOpen Access

Management of syncope associated with ventricular premature contractions in a dog

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Key result

Oral sotalol plus mexiletine controls severe ventricular arrhythmias and resolves syncope in LVH.

n=1

Why the study?

Syncope associated with ventricular premature contractions in dogs presents diagnostic and therapeutic challenges requiring detailed clinical management.

Key Points

To document the diagnostic findings and long-term anti-arrhythmic management of syncope and ventricular arrhythmias in a young dog with left ventricular hypertrophy.
Evaluated a four-year-old male Golden Retriever presenting with recurring episodes of syncope using physical examination, laboratory workups, radiography, electrocardiography (ECG), and echocardiography.
Initiated oral therapy with sotalol (0.5 mg/kg body weight BID), enalapril (0.25 mg/kg), and lasilactone (2 mg/kg), tapering prior phenobarbital treatment.
Adjusted sotalol to 1 mg/kg BID upon detecting peaked T waves at 4 months, and added mexiletine (4 mg/kg BID) after syncope and arrhythmias recurred at 6 months.
Initial therapy with low-dose sotalol resolved syncope and eliminated monomorphic ventricular premature contractions (VPCs) on ECG, but peaked T waves emerged at 4 months.
At 6 months, recurrent syncope presented with elevated creatine phosphokinase (286 U/L) and frequent monomorphic VPCs on ECG despite initial dose escalation.
Addition of mexiletine (4 mg/kg BID) to sotalol (1 mg/kg BID) normalized ECG rhythms within two weeks, eliminating VPCs and keeping the patient asymptomatic.

Study Design

Type

Case Report (n=1)

Structured PICO

P

Population

A 4-year-old male Golden Retriever dog presenting with recurrent syncope and ventricular premature contractions with moderate left ventricular hypertrophy, followed for over 6 months.

I

Intervention

Combination therapy of sotalol (1 mg/kg body weight twice daily) and mexiletine (4 mg/kg twice daily), along with enalapril and diuretics.

O

Outcome

Resolution of syncope and ventricular premature contractionspatient reported

Limitations

The cause for cardiac hypertrophy was not elucidated with the available investigations.
Estimation of the specific isoenzyme CK-MB for myocardial injury was not performed.
Cause for cardiac hypertrophy was not elucidated with the available investigations
Lack of specific isoenzyme (CK-MB) estimation for myocardial injury

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Implication

A combination of sotalol and mexiletine safely and effectively resolved life-threatening ventricular premature contractions and syncope in a dog with moderate left ventricular hypertrophy.

Abstract

A four-year-old male Golden Retriever dog was presented with a history of episodes of syncope. Electrocardiography (ECG) revealed atrio-ventricular dissociation and monomorphic ventricular premature contractions (VPCs). Echocardiography revealed moderate left ventricular hypertrophy. The animal responded initially with the treatment of anti-arrhythmic drug,Sotalol at the dose rate of 0.5 mgkg body weight BID along with Enalapril, diuretics and antibiotics. However, after few months, the animal showed peaked T waves in ECG, indicating myocardial hypoxia and the Sotalol dose was increased to 1 mgkg body weight BID. The animal again showed an attack of syncope with VPCs, six months after the initiation of treatment and responded well with the combination therapy of Sotalol at the rate of 1 mgkg BID and Mexiletine at the rate of 4 mgkg BID.

Discussion

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Cite This Study

Dr et al. (2026) conducted a case report in Syncope associated with ventricular premature contractions (n=1). Sotalol and Mexiletine combination therapy was evaluated on Resolution of syncope and ventricular premature contractions (VPCs). A combination therapy of oral sotalol and mexiletine effectively controlled life-threatening ventricular premature contractions and resolved syncope in a dog with left ventricular hypertrophy.

synapsesocial.com/papers/6ad0fc6015427f6a840400b6 https://doi.org/10.51966/jvas.2026.57.2.363-367

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Management of syncope associated with ventricular premature contractions in a dog

Key Points

Study Design

Structured PICO

Limitations

Ask about this paper

Implication

Abstract

Discussion

Cite This Study

Management of syncope associated with ventricular premature contractions in a dog

Key Points

Study Design

Structured PICO

Limitations

Ask about this paper

Implication

Abstract

Discussion

Cite This Study

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