The phenobarbital is a very widely used anti-seizure
medication. It is highly metabolized by the liver and over time, cause liver enzymes to rise.
Keppra (levetiracetam) is mostly excreted by the kidneys are is one of the safest drugs speaking in terms of therapeutic vs. toxic blood concentrations. Other drugs include zonisamide, potassium bromide, etc. A large percentage of dogs respond to one anti-seizure medication. For some, one is not enough and they need 2, 3, or 4 others!