Feasibility of Non-Invasive Vagus Nerve Stimulation (gammaCore VET™) for the Treatment of Refractory Seizure Activity in Dogs.

Kelsey Robinson,Simon Platt,Georgina Stewart,Lisa Reno,Renee Barber,Lindsay Boozer

doi:10.3389/fvets.2020.569739

Kelsey Robinson, Simon Platt + Show 4 more

Open Access

https://doi.org/10.3389/fvets.2020.569739

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Abstract

Idiopathic epilepsy is the most common chronic neurologic condition in dogs. Approximately 20–30% of those dogs are refractory to standard medical therapy and commonly experience side effects from antiepileptic drugs. Non-invasive vagus nerve stimulation (nVNS) has been frequently used in human medicine as an adjunct seizure therapy with low incidence of adverse events. Canine studies are limited to invasive surgical implants with no non-invasive evaluations currently published. We investigated the feasibility and efficacy of nVNS (gammaCore VET) as an adjunct treatment for refractory epilepsy in dogs. In total, 14 client-owned dogs completed the trial of either 8- or 16-week treatment periods during which they received 90–120 s stimulation three times per day in the region of the left cervical vagus nerve. Owners recorded seizure type (focal or generalized) and frequency as well as any adverse effects. Out of 14 dogs, nine achieved a reduction in seizure frequency and four were considered responders with a 50% or greater reduction in seizures from baseline to the final treatment period. However, there was no statistically significant difference in overall seizure frequency (p = 0.53) or percent change in seizure frequency between groups (p = 0.75). Adverse effects occurred in 25% of dogs originally enrolled, with reports of a hoarse bark and limb trembling, lethargy, behavioral changes, and an increase in seizure frequency. Non-invasive VNS was found to be safe and easy to administer with mild adverse events. It is considered a feasible treatment option as an adjunct therapy in refractory seizures and should be further investigated.

Highlights

Idiopathic epilepsy is the most common chronic neurological condition in dogs, with reported prevalence ranging from 0.5 to 5% [1,2,3]
Of dogs with idiopathic epilepsy, 20–30% are refractory to treatment with standard antiepileptic medications, and less than half are able to maintain a seizure-free status without experiencing side effects [4, 5]
Non-invasive vagus nerve stimulation has been utilized in humans for adjunct seizure therapy with reports of seizure reduction rates ranging from 23 to 64.4% [11, 18,19,20]

Summary

Introduction

Idiopathic epilepsy is the most common chronic neurological condition in dogs, with reported prevalence ranging from 0.5 to 5% [1,2,3]. Of dogs with idiopathic epilepsy, 20–30% are refractory to treatment with standard antiepileptic medications, and less than half are able to maintain a seizure-free status without experiencing side effects [4, 5]. These patients may have multiple seizure episodes over short time periods, contributing to primary brain injury from excitotoxic. Vagus nerve stimulation (VNS) may serve as an alternative or adjunct therapy for dogs with refractory epilepsy This method has been utilized in human medicine for treatment of various diseases, including pharmacoresistent epilepsy and status epilepticus [7, 8]. Clinical evaluation of a surgically implanted vagus nerve stimulator in dogs found up to 50% reduction in seizure frequency in four of nine dogs [9]

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