Updated November 28, 2020
Idiopathic epilepsy is the leading cause of seizures in dogs. If you’re already sure that’s what’s wrong with your dog, this page is for you.
What Is Idiopathic Epilepsy?
In theory, idiopathic epilepsy is a specific brain disease. In practice, it is a seizure disorder for which no cause can be established.
We don’t find the cause for most dogs who have seizures. Epilepsy is the catch-all term for these. Sometimes you can identify and avoid a trigger, but most of the time seizures seem to come out of nowhere.
Diagnosis of idiopathic epilepsy is by exclusion:
- No history of access to poisons
- A description of a typical epileptiform seizure (if you can take a video it’s very helpful to distinguish from collapse due to heart failure)
- Onset of signs under 6 years of age
- A normal physical examination and blood tests
- Minimal progression or worsening over time
It is perfectly OK to go directly to treatment if you’ve ticked all these boxes. Dogs with prolonged seizures or clusters, worsening over time, onset over 6 years of age or any findings on exams or tests need further testing or referral.
Please also note that many of the causes of tremors and shaking are easily confused with seizures. Examples are ‘white shaker syndrome’ in small & toy breeds and ‘canine epileptoid cramping syndrome’ in Border Terriers. Click the link to read more.
Treatment of Idiopathic Epilepsy
First, is treatment really necessary? Assuming your vet agrees, there is rarely any need to treat partial seizures other than identifying and avoiding the triggers.
There is also no need to treat very occasional generalised seizures if they cause no lasting effects, are short in duration and you are able to cope personally.
Cluster seizures and status epilepticus must always be treated urgently. The only way to stop prolonged seizures is for a vet to give emergency drugs.
Treatment involves a number of medications, usually added in the following order:
Despite its poor reputation in humans, ‘phenobarb’ remains the most effective seizure medication in dogs. It is usually extremely well tolerated and very cost effective. When first used, it causes sedation that wears off after a week and from then on should have no ill effects.
Dogs on phenobarbitone need periodic blood tests for liver enzymes as well as levels of the actual drug. Often the dose needs to be increased from its starting level for best results.
Potassium bromide is rarely very effective on its own but adds significantly to seizure control when used together with phenobarbitone. Once again, it’s usually very safe but monitoring is required. It should be given with food.
Bromide is slow to take full effect, with blood levels increasing right up to four months from the start of therapy. That said, we expect better control within a few weeks of starting.
Pexion® is a new drug registered in Australia as an aid in the treatment of idiopathic epilepsy in dogs. Our personal experience is that it is less effective than the drugs listed above but is useful for cases where control is difficult.
Of the unlicensed human medications, we have some success with levetiracetam for cases that respond poorly to standard therapy or when side effects are excessive. The drug is very fast acting and appears mostly well-tolerated. Now that there’s a generic form, it’s also not as expensive as it used to be.
Most other drugs made for human epilepsy are very disappointing in dogs, but can be tried in an ‘off-label’ way for difficult cases. We usually recommend consulting a specialist before using these.
That is the final message: treatment of seizures is not perfect. We often get excellent results, but seizures in some dogs can remain frustratingly hard to control. However, even if we can’t stop them completely, nearly every dog should get some benefit from treatment.
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By Andrew Spanner BVSc(Hons) MVetStud, a vet in Adelaide, Australia. These help topics are from a series regularly posted on email and Twitter. Subscribe via email here to never miss a story! The information provided here is not intended to be used as a substitute for going to the vet. If your pet is unwell, please seek veterinary attention.