Approach to seizures
Watching your dog have a seizure is frightening, and the first question is almost always why it happened.
Seizures in dogs fall into three main categories. Which one your dog fits determines what we test for and how we treat it.
The Three Main Causes
Cause 1
Reactive Seizures
A normal brain reacting to something circulating in the blood — a toxin or an organ problem. Because the brain itself is healthy, behavior between seizures varies widely.
Common triggers:
- Toxins
- Medications
- Metabolic (organ) disorders — liver disease, kidney disease
Diagnostics recommended: blood testing and x-rays
Cause 2
Secondary Epilepsy
A structural problem — either a genetic defect of the brain or a growth creating pressure. There is usually some abnormal behavior between seizures, though not always, since the brain may be normal or abnormal.
Structural causes include:
- Blood vessel abnormalities, malformed fluid valves or tracts
- Abscess (a pus-filled pocket)
- Inflammation from viral or bacterial infection (encephalitis)
- Trauma
- Cancer
Diagnostics recommended: MRI, with or without a spinal tap
Cause 3
Idiopathic Epilepsy
Seizures with no identifiable cause. Onset typically falls between six months and six years of age, with normal behavior and normal examination findings between episodes.
Diagnosis rests on: a consistent age of onset plus normal blood testing
When to Start Daily Medication
The goal of treatment is complete elimination of seizures, but realistically up to three seizures per year can be expected. We generally recommend starting daily anti-seizure medication when any one of these applies.
Frequency
More than once a month.
Intensity
Five-minute seizures every two months or less.
Cluster
More than two seizures in a 24-hour period.
Increasing trend
Episodes happening closer together than before — for example January, then May, then July, then August.
Keep a Seizure Diary
This is one of the most useful things you can do. Note the date, time, and length of every seizure, along with anything unusual beforehand. The pattern over time is what tells us whether treatment is needed and whether it's working.
Medication Options
Which drug to start with is genuinely open to debate — each has its own advantages and trade-offs, and the right choice depends on your dog.
Phenobarbital
The most commonly used anti-seizure medication. Requires monitoring for effects on the liver.
Zonisamide
Has the least sedative effect of the three.
Keppra (Levetiracetam)
The fastest acting, but requires dosing three times a day.
Has your dog had a seizure?
Bring your seizure diary if you have one. We'll work through which category fits and what testing makes sense.