J.C. Hardin, DVM
Pets can have seizures for many reasons. The most common cause is 'idiopathic epilepsy'. Though 'idiopathic' means the cause is unknown, many suspect an inherited issue. Other causes of seizures include liver shunts (congenital or acquired), low blood sugar (hypoglycemia), irregular heart beats (arrhythmias), brain tumors, high blood fat levels (hypertriglyceridemia), low blood calcium (eclampsia as with nursing mothers), meningitis (inflammation of the covering of the brain and spinal cord), distemper virus, rabies virus, FIP virus (cats), toxoplasmosis, neospora, poisons such as antifreeze, lead, pyrethrins, arsenic and others, drug overdoses (such as ivermectin), head trauma, migration of worm larvae (baylisascaris from raccoons for instance), brain granulomas (GME), loss of oxygen (from anemia, strangulation, arrhythmias), brain swelling (as with heat stroke or head trauma), and others. If your pet has high blood fat levels even after being strictly fasted for 12 hours, simply switching to a high fiber, low fat diet such as R/d may stop the seizures. Idiopathic epilepsy is the most common cause of seizures. As the name implies, the cause is unknown, but an inherited factor is suspected. Many epileptics have their first seizure during sleep, when brainwave activity is closest to the seizure threshold. Stressful events often make pets more prone to seizures. Boarding, fireworks, thunder, company in the house, new pets or children in the house, and moving to a new home, are some of these. Many pets are temporarily blind after seizures. Seizures that occur close together are called 'cluster seizures'. Cluster seizures can lead to brain swelling which requires oxygen, head elevation, mannitol, and often steroids to help get under control. Sometimes even aggressive efforts are not sufficient to control brain swelling and death may occur. In the hospital, repeated seizures are controlled with medications such as diazepam, propofol, levetiracetam, and pentobarbital. Most veterinarians don't start epileptics on preventive medication until a pet has had more than one seizure in a 30 day period. One cluster event is enough to qualify for this. Most commonly, phenobarbital is prescribed first. Potassium bromide is often added later, and can be used as a sole agent to control epilepsy. Gabapentin and Keppra (levetiracetam) are sometimes used as well. Phenobarbital is usually given every 12 hours. The law allows a pharmacy to only dispense a 30 day supply at a time, and no more than 5 refills per prescription. Phenobarbital is a schedule IV DEA controlled substance. Regular blood tests to assess serum phenobarbital levels are needed throughout a patient's life while on phenobarbital. Dose increases are usually needed intermittently throughout life. It is a good idea to check liver values at each phenobarbital test as well. Expect profound drowsiness for the first two weeks a pet is on phenobarbital. Less common side effects include itchy skin, aggression, bone marrow suppression, vomiting, diarrhea, and immune mediated anemia. Seek veterinary care without delay if you suspect a problem.