Epilepsy in Cats: Seizures, Causes & Treatment
Last reviewed: May 2026
Cat Seizures Are Different from Dogs
In cats, seizures are more commonly caused by secondary problems (hypertension, hyperthyroidism, toxins, FIP) than by the genetic idiopathic epilepsy that dominates in dogs. Finding and treating the underlying cause is as important as seizure medication. Two critical facts: blood pressure must be measured in every cat with new seizures, and potassium bromide (KBr) cannot be used in cats — it causes fatal lung disease.
Watching your cat have a seizure is one of the most frightening things a pet owner experiences. This guide explains what's happening, how cats differ from dogs, what your vet will look for, and what long-term management involves.
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Analyze My Cat's BloodworkTypes of Seizures in Cats
Generalized (Grand Mal)
Affects the whole body. Loss of consciousness, muscle rigidity or paddling, jaw chomping, hypersalivation, dilated pupils, loss of bladder or bowel control. The most visually dramatic type.
Focal (Partial)
Affects one part of the body. Facial twitching, repetitive licking or chewing, one limb paddling, or apparent fly-biting at the air. Cat may remain conscious. More common as the initial presentation in cats with structural brain disease.
Cluster Seizures
Two or more seizures within 24 hours. The brain does not fully recover between events. Requires emergency care and often IV medication to break the cycle.
Status Epilepticus
A single seizure lasting more than 5 minutes, or continuous seizures without recovery. Life-threatening emergency. Brain damage and death can occur without immediate IV diazepam or midazolam.
Emergency Thresholds — Go Now
- • Seizure lasting more than 5 minutes
- • 2 or more seizures in 24 hours (cluster)
- • Cat not recovering normally within 30–60 minutes post-seizure
- • First seizure ever — always warrants same-day evaluation
- • Any seizure plus known or possible permethrin exposure — this is an immediate emergency
What a Seizure Looks Like: The Three Phases
- 1. Pre-ictal (Aura) — minutes before the seizure
Behavior changes — hiding, unusually vocal, clingy, restless, or staring blankly. Some owners learn to recognize their cat's aura and can move them somewhere safe before the seizure starts.
- 2. Ictal (The Seizure) — typically 1–3 minutes
Muscle rigidity, paddling, jaw chomping, hypersalivation, dilated pupils, loss of consciousness, urination or defecation. Time the seizure — this information is critical for your vet. Permethrin toxicity often causes continuous muscle tremors rather than discrete seizures.
- 3. Post-ictal (Recovery) — minutes to hours
Confusion, disorientation, temporary blindness, hiding, excessive vocalization, or profound tiredness. Keep your cat in a safe room away from stairs and hazards. Don't try to restrain them — they may bite or scratch without intending to.
Causes of Seizures in Cats
Unlike dogs, where idiopathic (genetic) epilepsy dominates, cats are more likely to have a findable, treatable underlying cause. Thoroughly ruling out secondary causes before assuming idiopathic epilepsy is essential.
Hypertension (High Blood Pressure)
The most commonly overlooked cause of seizures in cats. Severely elevated blood pressure (systolic >200 mmHg) damages small brain blood vessels, causing hypertensive encephalopathy. Almost always secondary to CKD or hyperthyroidism. Blood pressure measurement is required in every cat with new seizures, especially seniors. Treatment (amlodipine) often resolves seizures without anti-epileptic drugs.
Hyperthyroidism
Elevated T4 drives hypertension, which causes brain damage over time. T4 must be checked in any senior cat with new-onset seizures — even if other signs of hyperthyroidism aren't obvious. Treating hyperthyroidism with methimazole or radioiodine often controls seizures as blood pressure normalizes.
Meningioma (Brain Tumor)
Meningioma is by far the most common brain tumor in cats — more than 50% of feline intracranial tumors. Unlike in dogs, feline meningiomas are often well-defined and surgically resectable. Average age of onset is 12 years. Many cats have a good outcome with surgery (median survival >2 years post-op). Seizures often present late in the course alongside gradual behavioral changes.
FIP (Feline Infectious Peritonitis)
The neurological (dry) form of FIP causes granulomatous inflammation in the brain and spinal cord, leading to focal or generalized seizures, ataxia, and behavior changes. CSF analysis shows characteristic high protein with inflammatory cells. Antiviral therapy (GS-441524) has transformed prognosis — neurological FIP is now treatable.
Ischemic Encephalopathy
Stroke-like events in cats — sudden loss of blood supply to part of the brain. Causes acute onset of focal neurological deficits (head tilt, circling, blindness) that may progress to seizures. Cuterebra larvae migration is a recognized cause in some regions (spring/summer). Most cats improve with supportive care, though permanent deficits are possible.
Idiopathic Epilepsy
Does occur in cats — more commonly in young adult cats under 7. Diagnosis of exclusion: all metabolic causes, hypertension, MRI, and CSF must be normal. Less well-characterized genetically in cats than in dogs. May be more common in certain breeds but breed predisposition data in cats is limited.
Permethrin Toxicity: The #1 Toxin Emergency in Cats
Permethrin is found in many dog-specific flea and tick products (K9 Advantix, some spray collars). Cats cannot metabolize it. Even small skin exposures — from a dog product applied directly or from contact with a treated dog — cause severe, continuous muscle tremors and seizures within hours.
- • Signs: severe tremors, hypersalivation, hyperthermia, paddling seizures
- • Treatment: IV methocarbamol (muscle relaxant), whole-body washing, cooling, supportive care
- • Prognosis: excellent with prompt treatment — most cats recover fully
- • Timing is critical: don't wait, go immediately
Always check dog flea product labels before using in a multi-pet household.
Age at First Seizure in Cats
Under 7 years: Consider toxins, FIP, portosystemic shunt, metabolic disease, idiopathic epilepsy.
7–10 years: Hyperthyroidism and hypertension rise in importance — T4 and blood pressure are essential.
Over 10 years: Meningioma, hypertensive encephalopathy, CKD-driven hypertension, and ischemic events are the most common causes. MRI is warranted in most senior cats with new seizures.
Bloodwork: What Your Vet Is Looking For
A full metabolic and systemic workup is required before any diagnosis or treatment decision. In cats, this must include blood pressure measurement — something not always done automatically.
| Test | Why It's Checked |
|---|---|
| Blood pressure (BP) | Hypertension is the most commonly missed cause — must be measured in every cat with new seizures |
| T4 (thyroid) | Hyperthyroidism drives hypertension and seizures; T4 is essential in any cat over 7 |
| BUN + Creatinine + SDMA | CKD is the most common cause of secondary hypertension in cats |
| ALT + ALP + GGT | Hepatic encephalopathy from liver disease; also establishes baseline before phenobarbital |
| Glucose | Hypoglycemia causes seizures; insulinoma possible in any age cat |
| Electrolytes (Na, K, Ca) | Severe imbalances trigger seizures; low calcium or sodium are notable cat causes |
| CBC | Polycythemia vera causes hypertension; FeLV/FIV status matters for CNS disease risk |
| FeLV/FIV test | FeLV-related CNS disease; FIV increases vulnerability to FIP and opportunistic CNS infections |
| Urinalysis | Kidney assessment; urine specific gravity helps CKD staging |
Keep your cat's pre-treatment and monitoring results in one place
Upload your cat's bloodwork to VetLens and track kidney values, thyroid, and liver enzymes across every monitoring appointment.
Track My Cat's Monitoring ResultsTreatment: Phenobarbital and Other Options
Before starting anti-epileptic drugs, treating an identifiable underlying cause (hypertension, hyperthyroidism) often resolves seizures. When medication is needed, the threshold is similar to dogs: two or more seizures in 6 months, cluster seizures, or status epilepticus.
Phenobarbital
First-lineThe most effective and best-studied anti-seizure drug for cats. Given twice daily. Therapeutic range: 20–40 μg/mL. Cats reach steady state more slowly than dogs — wait at least 3 weeks before the first level check. Side effects: initial sedation, increased appetite, and increased thirst/urination (usually temporary). Long-term: liver enzyme elevation and risk of hepatotoxicity, requiring 6-month monitoring.
Levetiracetam (Keppra)
Alternative / Add-onMinimal liver effects, no required serum level monitoring beyond standard safety checks. Downside in cats: requires three times daily dosing (short half-life), which can be challenging long-term. Extended-release formulations may help. Often used in cats with existing liver disease or when phenobarbital has been insufficient.
Zonisamide
Emerging optionTwice-daily dosing, less data in cats than dogs but generally well tolerated. Requires monitoring for metabolic acidosis and kidney stones with long-term use. Used in cats that don't respond to phenobarbital alone.
Potassium Bromide (KBr)
NEVER IN CATSPotassium bromide causes severe allergic bronchopneumopathy (lung disease) in cats — even at standard doses used successfully in dogs. It is absolutely contraindicated in cats. This is one of the most important species-specific drug differences in veterinary neurology.
Monitoring Schedule for Cats on Phenobarbital
Long-term epilepsy management means repeat bloodwork, indefinitely. Cats on phenobarbital also need blood pressure checks built into the schedule, since hypertension management and seizure management are often interconnected.
| Timepoint | Tests |
|---|---|
| Before starting | Full chemistry, CBC, T4, blood pressure, FeLV/FIV, urinalysis — baseline and cause rule-out |
| 3 weeks after starting | Serum phenobarbital level (trough — draw just before a dose) |
| 6 months | Phenobarbital level + full chemistry (ALT, ALP, GGT, kidney values) + blood pressure + T4 if senior |
| Every 6 months ongoing | Same as above — for life |
| After any dose change | Serum phenobarbital level 3 weeks post-change |
Phenobarbital and Cat Liver Enzymes
Phenobarbital reliably raises ALP and ALT in cats. Unlike dogs, where high ALP is often dismissed, even mild ALP elevation in cats is significant — so the drug-induced rise needs to be tracked carefully. If enzymes trend significantly upward over multiple monitoring panels, your vet may reduce the dose, switch medications, or add liver-protective supplements.
This is why uploading every monitoring panel matters. A single elevated value is ambiguous — a consistent upward trend across 12–18 months is the signal your vet needs.
At-Home Seizure Management
- • Keep a seizure diary. Date, time, duration, type, and recovery time — the most useful information you can bring your vet.
- • Time every seizure. It's hard to judge duration in the moment — set a timer when it starts.
- • Don't put your hands near the mouth. Cats cannot swallow their tongue. Your hands can be injured, and a biting cat in post-ictal confusion doesn't know what they're doing.
- • Move hazards away. Protect from falls (cats on high surfaces), stairs, and sharp corners. Use rolled towels to cushion the head if on a hard floor.
- • Dim lights and reduce noise during and after the seizure.
- • Never stop phenobarbital abruptly. Sudden discontinuation triggers severe rebound seizures. Always taper under veterinary guidance.
- • Remove permethrin products from your home. If you have a cat and a dog, check every flea product label. Advantix, Vectra 3D, and many generic spot-on flea products contain permethrin and are unsafe in cat households.
Questions About Your Cat's Seizure Medication?
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Key Takeaway
Cat seizures have more treatable underlying causes than dog seizures. Before accepting a lifelong epilepsy diagnosis, make sure blood pressure was measured and T4 was checked — these two tests catch the most common correctable causes.
For cats on phenobarbital, the commitment is the same as in dogs: liver panels and drug levels every 6 months for life. Consistency with monitoring catches toxicity before it becomes a crisis.
Related Reading
Track Your Cat's Phenobarbital Monitoring
Upload each monitoring panel to VetLens and see:
- ✓ ALT, ALP, and GGT trends over every appointment
- ✓ Kidney values to catch early drug effects
- ✓ Side-by-side comparison of pre-treatment vs current values
- ✓ Plain-language explanation of what each change means
Frequently Asked Questions
What causes seizures in cats?
Cats are more likely than dogs to have a secondary (treatable) cause. The most important to rule out are hypertension (often from CKD or hyperthyroidism), hyperthyroidism itself, permethrin toxicity, FIP affecting the CNS, meningioma, and ischemic encephalopathy. Idiopathic epilepsy does occur in cats but is less common than in dogs.
When is a cat seizure an emergency?
Go immediately if a seizure lasts more than 5 minutes (status epilepticus), if there are 2+ seizures in 24 hours (cluster), if your cat doesn't recover normally within 30–60 minutes, or if this is a first seizure. Any seizure with possible permethrin exposure is also an immediate emergency.
Can I use potassium bromide for my cat's seizures?
No. Potassium bromide causes fatal lung disease in cats and is absolutely contraindicated. This is one of the most important drug differences between dogs and cats. Use phenobarbital or levetiracetam instead.
Why is blood pressure checked in cats with seizures?
Hypertension is one of the most common and most correctable causes of seizures in cats — far more so than in dogs. It's almost always secondary to CKD or hyperthyroidism. Treating the blood pressure (usually with amlodipine) often resolves seizures without needing long-term anti-epileptic drugs.
What is permethrin toxicity in cats?
Permethrin is found in dog-specific flea products. Cats cannot metabolize it — even small exposures cause severe continuous muscle tremors and seizures. It is the most common feline toxicology seizure emergency. Treatment with IV methocarbamol is highly effective if given promptly. Never use dog flea products on cats or in households with cats unless verified permethrin-free.
What bloodwork does a cat with epilepsy need?
Before treatment: full chemistry, CBC, T4 (thyroid), blood pressure measurement, FeLV/FIV test, and urinalysis. T4 and blood pressure are cat-specific additions that dogs don't routinely need. Once on phenobarbital: serum drug level at 3 weeks, then liver enzymes and drug level every 6 months for life.
What is the most common brain tumor causing seizures in cats?
Meningioma — accounting for over 50% of feline brain tumors. Unlike dogs, feline meningiomas are often well-defined and surgically resectable with good outcomes (median survival >2 years post-op). They typically affect cats over 10 years old with gradual behavioral changes before frank seizures.