Disease and Illnesses of dogs – Epilepsy
What is Epilepsy?
Epilepsy is a condition which is caused by abnormal brain activity and results in affected pets having repeated seizures. These can be full body seizures or sometimes just localised seizures such as a twitching of the jaw. Epilepsy affects approximately 4 in 100 dogs but many more dogs may just have one episode of seizure activity in their life and this doesn’t mean that they have epilepsy. In dogs affected with epilepsy, the onset of seizures is usually between 2 and 8 years of age. There are many other potential causes of seizures, other than epilepsy so some investigation is needed to get a definitive diagnosis of epilepsy.
How is Epilepsy diagnosed?
Epilepsy is really a diagnosis of exclusion which means that all the other potential causes of seizures need to be ruled out before you can say definitively that Epilepsy is the cause. The first step will be your vet giving your pet a thorough clinical examination and taking a history from yourself about the timings of the seizures and what exactly happened. Try and be as specific as you can, video episodes if possible and if they are recurring then keep a diary of events so you are sure of the frequency.
The next step is likely to be a full blood screen which can rule out many of the non brain related causes of seizures such as liver disease or abnormalities in blood glucose. This is not a very invasive test and can be done at your local vet surgery and you should get the results immediately.
The next step in diagnosis is to perform imaging of the brain and this is done with an MRI scan. This is usually only available at specialist centres as an MRI scanner is a very specialist piece of equipment. It is not always an option for every patient due to availability and cost issues but it is the only way of looking into the brain and seeing what is happening and ruling out masses in the brain of other abnormalities that can cause seizures. Treatment for seizures can be started without an MRI scan if one is not available.
If an underlying cause of seizures other than epilepsy is found then that needs to be treated in order to control the seizures.
How and when is Epilepsy Treated?
There are a range of medications that can help to control the seizures but they are not without side effects so whether you treat seizures caused by epilepsy depends on the frequency and severity of seizures. Seizure medications, also called anti-convulsants, do not stop the seizures completely, they aim to control them by making them less frequent and less severe when they do happen. For example, if a dog only had a seizure every 6 months and it was short and they recovered well, there may not be a benefit to treatment. If seizures are happening on a weekly basis and they are over 5 minutes each then treatment would be warranted. There is no definite rule as to when to start treatment, it is decision that should be made after discussion between you and your vet.
Emergency Treatment of Seizures: If your pet is having a seizure that is continuing for longer than 10 minutes you must contact your vet ASAP. This is called Status epilepticus and needs veterinary intervention as can be dangerous if left untreated.
Phenobarbitone: This is usually the first medication that is given to control seizures. Phenobarbitone is a drug in the barbiturate class and the trade name is Epiphen. The exact dose of Epiphen that is required by your pet will be determined by your vet. Epiphen comes as tablets in various sizes for ease of accurate dosing. It is also available as an injectable solution which can be used in the acute treatment of seizures.
Phenobarbitone works by depressing the nervous system, making seizures less likely. This depression is not restricted just to the areas causing seizures but to the whole nervous system so it can also have some side effects, the most common being a sedative effect, lethargy, increased hunger, thirst and urination. These side effects can be worse if the dose is too high so regular monitoring is needed.
It is the amount of phenobarbitone that is absorbed into the blood that is important, not how much is being given orally so blood levels of the drug need to monitored regularly, usually every three weeks until an effective level is reached and then approximately every 6 months. Bloods will also need to be taken regularly to measure liver enzymes as prolonged use of phenobarbitone can have effects on the liver.
Potassium Bromide (KBr): This can be added in if the maximum dose of phenobarbitone has been reached but the seizures are not adequately controlled. The potential side effects are similar to phenobarbitone, increased lethargy, hunger, thirst and urination but these side effects are often temporary and will resolve if treatment is continued. If they persist then seek advice from your veterinary surgeon. Regular monitoring is again essential to check that levels of Potassium Bromide are effective but within the recommended range.
Diazepam: Diazepam is in the benzodiazepine class of drugs and is used in an acute situation when an animal is having a seizure and the vet needs to intervene to stop it. In this situation it is used either as an injectable solution or as a preparation which is given rectally as it is well absorbed into the bloodstream from that site. Rectal diazepam tubes can also be dispensed to owners of epileptic animals so it can be administered in prolonged seizures or during clusters of seizures to stop further seizure activity.
There are other drugs that can be used in conjunction with these if seizures are proving difficult to control of if seizures are happening in clusters with several seizures very close together. These include Gabapentin and Levetriacetam (Keppra).