Seizure Control in Dogs

Approximately 20% to 30% of epileptic dogs do not have satisfactory seizure control. The antiepileptic drug levetiracetam (LEV) was evaluated in 34 client-owned dogs with idiopathic epilepsy resistant to treatment with phenobarbital and bromide. LEV was administered at 20 mg/kg PO q8h in addition to current antiepileptic medications. Each dog underwent 2 16-week treatment periods (drug and placebo), with a 4-week washout period between treatments. Twenty-two dogs completed the study; 6 died or were euthanized, including 4 deaths caused by uncontrolled seizures. There was no significant difference of weekly seizure frequency compared with placebo. Owners reported ataxia, restlessness, anorexia, and vomiting as common side effects; 57% of LEV dogs and 43% of placebo dogs experienced an adverse event. There were no changes in CBCs, serum biochemistry profiles, urinalyses, or mean serum phenobarbital and bromide concentrations when LEV was administered compared with placebo. Owners reported increased quality of life with LEV, although no increased efficacy was noted over placebo.

CommentaryThis study emphasized the importance of randomized, placebo-controlled, double-blinded, crossover studies for evaluating new seizure medications and that open-labeled trials may overestimate treatment efficacy. The significant decrease in weekly seizure frequency, regardless of treatment order, reflects the placebo effect, something that open-label trials do not consider. This study failed to demonstrate the efficacy of LEV over placebo as add-on therapy in dogs with refractory epilepsy. It also illustrated the danger of extrapolating data from human studies to dogs, more specifically the therapeutic range for LEV, which has not been established in humans. As in humans, there was no association between LEV and response to treatment.—Helena Rylander, DVM, DACVIM (Neurology)

SourceEvaluation of levetiracetam as adjunctive treatment for refractory canine epilepsy: A randomized, placebo-controlled, crossover trial. Muñana KR, Thomas WB, Inzana KD, et al. J VET INTERN MED 26:341-348, 2012.