The objective when treating a patient with refractory epilepsy is to control the seizures without drug toxicity. This is accomplished in a stepwise fashion: 1) use a drug known to be effective in the species being treated, 2) verify that the owner is complying with the prescribed dosage regimen, 3) monitor serum drug levels with samples taken at trough blood concentrations, 4) observe for adverse drug reactions/interactions, and 5) test for metabolic or structural brain injuries that would explain the poor drug response. By following these steps and individualizing the treatment for each patient, you should be able to obtain seizure control in the majority of patients.