Peer-reviewed veterinary case report
Mexiletine treatment for ventricular arrhythmias in dogs safety
By Romito, Giovanni et al.·Published in Journal of the American Veterinary Medical Association·2025·Alma Mater Studiorum-University of Bologna, Italy·View original on PubMed →
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Original publication title: Antiarrhythmic efficacy and safety of oral mexiletine in dogs with ventricular arrhythmias: a multicentre, retrospective analysis.
- Species:
- dog
Plain-English summary
A group of dogs with heart rhythm problems, known as ventricular arrhythmias, were treated with a medication called mexiletine to see if it could help. Out of 20 dogs monitored, mexiletine successfully reduced the arrhythmias in 16 of them, which is about 80%. However, some dogs experienced side effects like stomach issues and neurological signs, leading to adjustments in their treatment. Most of these side effects resolved with supportive care, but a few dogs had to stop the medication due to ongoing problems. Overall, mexiletine proved to be effective but came with some risks.
People also search for: dog heart rhythm problems treatment · mexiletine side effects in dogs · ventricular arrhythmias in dogs
Abstract
OBJECTIVE: To describe mexiletine's efficacy in suppressing ventricular arrhythmias (VAs) and its safety in dogs. METHODS: In a multicenter retrospective study, dogs received oral mexiletine, prescribed as a second-line antiarrhythmic in addition to a first-line agent, for the treatment of VA ineffectively controlled by initial monotherapy. Signalment, clinical, diagnostic, therapeutic, and outcome data were retrieved. Only dogs that underwent Holter monitoring both before and after starting mexiletine treatment were included in the ECG analysis of efficacy. This was represented by a reduction in the Lown-Wolf grade < 5 or a reduction in the number of ventricular premature complexes ≥ 85%. Treatment-related side effects (TRSE) were noted in all dogs. Statistical analysis was performed to compare selected data before and after mexiletine prescription. RESULTS: 38 dogs were included. Twenty dogs met the criteria for the efficacy analysis; mexiletine effectively suppressed VA in 16 of 20 cases (80%). In 11 of 38 dogs (28.9%), TRSE occurred (ie, gastrointestinal and neurological signs in 10 of 11 [90.9%] and 1 of 11 cases [9.1%], respectively). Supportive therapies were prescribed to 10 of 11 dogs (90.9%) and the daily dose of mexiletine was reduced in 6 of 11 dogs (54.5%), resulting in resolution of TRSE in 5 of 11 dogs (45.5%). In the remaining 6 of 11 dogs (54.5%), the persistence of TRSE led to the discontinuation of mexiletine. The median duration of TRSE was 7 days (IQR, 4 to 10 days). CONCLUSIONS: Mexiletine was highly effective in suppressing VA, but reversible gastrointestinal TRSE occurred relatively frequently. CLINICAL RELEVANCE: Useful information on the effects of mexiletine in dogs with VAs is provided.
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Search related cases →Original publication on PubMed: https://pubmed.ncbi.nlm.nih.gov/40523634/