by Dr. William Thomas, DVM, MS Dipl. ACVIM (Neurology)
University of Tennessee
annual ACVIM forum in Charlotte, NC:
Curtis Dewey presented an abstract on using zonisamide (Zonegran) in 12 dogs with epilepsy
refractory to other drugs (mostly phenobarbital and bromide). Seven dogs (58%) had a
decrease in the number of seizures after starting zonisamide, with a mean decrease in
seizure frequency of 81%. In 8 of these dogs, it was possible with decrease the dose or
withdraw concurrent anti-seizure drugs. Side effects were very mild.
on Zonegran for Dr. Thomas:
caught my attention and I wondered how this AED is metabolized?
In the dog, zonisamide
we use 10 mg/kg every 12 hours
is metabolized by the liver, with an elimination half-life of 15 hours.
Zonisamide seems to be
an effective "second-line" drug in dogs, based on limited clinical experience.
It's elimination half-life is 15-20 hours in dogs, so it is usually given twice daily.
It's expensive. So far, side effects in dogs seem rare.