Telmisartan as an add-on treatment for dogs with refractory idiopathic epilepsy: a nonrandomized, uncontrolled, open-label clinical trial.

Objective: To evaluate the effect on seizure frequency of add-on telmisartan treatment in dogs with refractory idiopathic epilepsy.
Animals: 11 client-owned dogs with idiopathic epilepsy and ≥ 2 generalized seizures/mon that were currently being treated with ≥ 2 antiepileptic drugs.
Procedures: Telmisartan was administered at a dosage of 0.25 to 1 mg/kg, PO, every 12 hours for 4 to 16 months. Seizure frequencies before and during telmisartan treatment were recorded.
Results: 10 dogs completed the 4-month treatment protocol. One dog was excluded owing to a transient increase in serum creatinine concentration; no adverse effects of telmisartan were observed in the remaining 10 dogs. A reduction in seizure frequency greater than an estimated expected placebo effect of 30% was evident in 7 of the 10 dogs. Long-term (12 to 16 months) follow-up information was available for 6 dogs, of which 4 had a further reduction in seizure frequency. Differences in seizure frequency were not statistically significant. No significant difference was found in serum phenobarbital concentration throughout the treatment period in the 7 dogs that were tested.
Clinical Relevance: Telmisartan has the potential to reduce seizure frequency when administered as an add-on antiepileptic drug in dogs with refractory idiopathic epilepsy. A randomized, double-blind, placebo-controlled trial is needed to determine the true efficacy of telmisartan. On the basis of our results, a sample size of 54 dogs with refractory idiopathic epilepsy would be needed.