Felbamate as an oral add-on therapy in six dogs with presumptive idiopathic epilepsy and generalized seizures resistant to drug therapy

BACKGROUND: Idiopathic or genetic epilepsy commonly affects dogs; affected dogs are often refractory to anti-seizure drug therapy. Felbamate is an anti-seizure drug with established pharmacokinetic and safety data for dogs, but little published evidence of efficacy for managing generalized seizures in this species. AIM: The purpose of this retrospective case series was to evaluate the clinical efficacy and tolerability of oral felbamate in six presumptive epileptic dogs experiencing generalized seizures. METHODS: Medical records from six dogs with presumptive idiopathic/genetic epilepsy manifesting as generalized seizure activity, for which oral felbamate was used as an add-on treatment, were reviewed. The number of seizures recorded for the 3-month period immediately before instituting felbamate was recorded for each dog. Short-term (3 months) and long-term (6 months or greater) seizure frequency post-felbamate therapy was recorded for each dog and compared with baseline. RESULTS: Overall, dogs experienced a reduction (82%) in seizures after adding felbamate in the short term, with 5/6 dogs (83%) classified as responders (50% or greater reduction in seizures) and 3/6 dogs (50%) attaining seizure-free status. Mean and median long-term follow-up times were 13 and 11 months, respectively (range: 6 to 23 months). Four of the 6 dogs (67%) remained drug responders at final follow-up, with an average seizure reduction of 98%, 2 of which remained seizure-free at 8 and 21 months. Two dogs (33%) experienced increased seizure activity during long-term follow-up (12 and 23 months) and were considered non-responders. The non-responder dogs had an average long-term seizure reduction of 33%. No dog experienced any obvious adverse effects associated with felbamate administration. However, one dog not included in the analysis because of insufficient (<3 month) post-felbamate follow-up, was weaned off felbamate because of suspected hepatotoxicity. CONCLUSION: Our small case series suggests that oral felbamate might show promise as an add-on drug for epileptic dogs experiencing generalized seizures resistant to drug therapy. These results warrant a more controlled, prospective investigation into felbamate as a therapeutic agent for canine epilepsy.