Idiopathic Epilepsy is a common condition in Border Collies. It is known that Border Collies with epilepsy often respond poor to treatment with antiepileptics, especially to phenobarbital. The poor response to phenobarbital is also called phenobarbital resistance. Besides the phenobarbital resistance a lot of Border Collies are also affected by MDR1, making them more susceptible to side effects of certain types medication.

Phenobarbital resistance is (just like MDR1) caused by a defect in the blood-brain barrier. In the case of phenobarbital resistance the blood-brain barrier is to strong and does not transport enough phenobarbital from blood to brain. As a consequence phenobarbital will not reach it target organ, the brain, in high enough concentrations and making it unable cause the desired effect.

Phenobarbital resistance in Border Collies is not treatable, but fortunately can be tested with a DNA test ‘ MDR1 Multi Drug Resistance – Phenobarbital Resistance’ with test number H754.