Implantable vagus nerve stimulator settings and short-term adverse effects in epileptic dogs.

backgroundImplantable vagus nerve stimulation (VNS) devices can be used to treat epilepsy in dogs. Adverse effects and short-term complications associated with delivering suggested therapeutic electrical stimulation (>1.5 mA) are not well-described.

objectivesTo compare complications and adverse effects observed with standard and rapid protocols of current increase. ANIMALS: Sixteen client-owned dogs with idiopathic epilepsy.

methodsNonrandomized, nonblinded prospective cohort study. Surgical complications, stimulation-related adverse effects, modifications to stimulator settings, number of hospital visits, and time to reach 1.5 mA stimulation current without intolerable adverse effects were described in dogs receiving current increases every 1 to 3 weeks (slow ramping) and dogs receiving current increases every 8 to 12 hours (fast ramping).

resultsSelf-resolving surgery site seromas formed in 6 dogs. No other surgical complications were observed. Fourteen dogs reached 1.5 mA. Coughing (11/14 dogs; 5 slow, 6 fast ramping) was the most common adverse effect. Intolerable coughing that limited current increases despite changing other stimulus parameters occurred in 6/7 of the fast-ramping group and in none of the slow-ramping group. Median time to 1.5 mA was 72 days (range, 28-98) in the slow-ramping group and 77 days (range, 3-152) in the fast-ramping group. Median number of clinic visits was 6 for the slow-ramping group (range, 5-6) and 3 for the fast-ramping group (range, 1-7). CONCLUSIONS AND CLINICAL IMPORTANCE: Coughing is a common adverse effect of VNS in dogs and generally is well tolerated, particularly if current is increased slowly and other stimulation parameters are adapted for effect.