Emergency Management of Seizures
Written by Sean Sanders, DVM, PhD, Diplomate ACVIM (Neurology)
The effective emergency management of seizures can be the difference between life and death for some pets and in certain cases can prevent costly and long term hospitalization. Most pets will present with either a history of recent seizures or in status epilepticus (a seizure lasting more than 10-15 minutes). When presented with a patient that has a history of recent seizures, it is never wrong to start anti-convulsant therapy. Regardless of the cause of the seizures, stopping further seizures is the most important aspect of management to remember. If you are unsure of the pet's liver status, use phenobarbital and diazepam carefully.
The most effective medication that can be used to stop an immediate seizure is diazepam. The most common reason for diazepam failing to stop a seizure is that enough was not given. In general, use 1 ml IV for small dogs (5 - 10 kg), 2 ml IV for medium dogs (10 - 20 kg) and 3 ml or more IV for large dogs (greater than 20 kg). For cats use 0.25 - 1 ml IV. If you cannot get IV access give double the IV dose rectally. Use a red rubber feeding tube inserted about 4 - 6 inches in the rectum and given as a bolus. If after giving a dose of diazepam the seizure does not stop within 2 - 3 minutes (IV) or 5 min (rectal) then give another dose. It is not that uncommon to have to give 2 - 4 doses of valium before the seizure stops. It sounds like a lot but it is very safe. If an animal has compromised liver function or you are suspicious of liver disease (shunt or cirrhosis etc...) then give 1/4 of the estimated dose (diazepam or phenobarbital). Once the seizure is stopped you can give a loading dose of phenobarbital or potassium bromide. If you are going to refer the patient immediately, it might be better to wait on the loading dose so a more accurate exam can be performed. If the patient continues to have seizures after the initial doses of valium, they should be placed on a valium constant rate infusion. Use the amount of valium that it took to stop the seizure and give it over one hour as a CRI.
If the patient is not to be referred and you want to give a loading dose of an anticonvulsant use 10 - 15 mg/kg of phenobarbital as a single loading dose. Dilute the phenobarbital in 1 part saline to one part phenobarbital and give it IV slowly. There have been anecdotal reports of animals having an anaphylactic reaction to components of the injectable form of phenobarbital. You can also give the loading dose orally, if you are certain that the patient is alert enough to take oral medications. The loading dose of potassium bromide is the same dose as the maintenance dose (30 mg/kg) only given every 4 - 6 hours for a total of 13 doses (either oral or rectal) and then switched to every 12 hours for maintenance. Prior to referral, a CBC, biochemical profile and urinalysis can be performed. Bile acids (fasting and fed) are a great idea too but may take some time to get the results. We can perform bile acids in the hospital so it is not as critical that the patient has these sent out prior to referral. Older patients (older than 6 years) can have a three view metastasis check performed prior to referral as well.
Knowing when to start anticonvulsant therapy is always a concern. There are some specific times when the decision to treat is more definable (see right column). These are of course only guidelines. The primary decision will be based on the wishes of the owners and their comfort level with having a pet that has seizures.
Published on December 9, 2007.