Epiphen is the animal version of Phenobarbitone – this is the drug of choice for canine and the less common feline idiopathic epilepsy.
Initially it may cause sedation but dogs often adapt to this and become normal after a week or so. It will cause excess appetite and thirst sometimes.
It may cause liver toxicity and it decreases thyroid hormones. However it is used a lot and in our experience it is usually very well tolerated. Dogs whose fits are not easily controlled on Phenobarbitone often prove very difficult to control with other drugs. It is often necessary to do blood samples to define blood levels of the drug when fits are not readily controlled by typical oral doses.