Dog Seizures: Types, What to Do & When It's an Emergency

What Is a Seizure?

A seizure is a sudden, uncontrolled burst of abnormal electrical activity in the brain. It causes involuntary muscle contractions, changes in behavior, altered consciousness, and sometimes loss of bodily functions. Seizures are not a disease themselves but rather a symptom of an underlying brain abnormality or systemic condition affecting the brain. Approximately 1–5% of all dogs experience seizures at some point in their lives, making it one of the most common neurological conditions in dogs.

Types of Seizures

Grand Mal (Generalized Tonic-Clonic) Seizures

Grand mal seizures are the most recognized and dramatic type. They involve the entire body and follow a characteristic pattern. During the tonic phase, the dog falls to its side, becomes rigid, and may stop breathing briefly — this phase usually lasts 10–30 seconds. The clonic phase follows with rhythmic paddling or jerking of the legs, chomping jaw movements, and sometimes drooling or foaming at the mouth. The dog is unconscious during this phase. It's common for dogs to urinate, defecate, or vocalize (howl or cry) involuntarily. Most grand mal seizures last 30 seconds to 2 minutes.

Focal (Partial) Seizures

Focal seizures originate in one area of the brain and affect only one part of the body. You might see twitching of one side of the face, rhythmic blinking, jerking of a single limb, or snapping at invisible flies (“fly-biting” seizures). The dog may remain conscious or have altered awareness. Focal seizures can be subtle and easy to miss. Importantly, a focal seizure can generalize — meaning it starts in one area and then spreads to become a full grand mal seizure. Focal seizures in dogs older than 5 years raise concern for a structural brain lesion such as a tumor.

Cluster Seizures

Cluster seizures are defined as two or more seizures within a 24-hour period with the dog regaining consciousness between episodes. Cluster seizures are a medical emergency because each seizure lowers the threshold for the next one, creating a dangerous cycle that can escalate to status epilepticus. Certain breeds are predisposed to cluster seizures, including German Shepherds, Border Collies, Boxers, and Cavalier King Charles Spaniels.

Status Epilepticus

Status epilepticus is a seizure that lasts longer than 5 minutes or two or more seizures without the dog fully regaining consciousness between them. This is a life-threatening emergency. Prolonged seizure activity causes dangerous overheating (hyperthermia), brain damage, respiratory failure, and can be fatal. Status epilepticus requires immediate emergency veterinary care with intravenous anticonvulsant medication.

What to Do DURING a Seizure

When your dog has a seizure, your instinct will be to help. Here is exactly what you should and should not do:

1. Stay calm. Your dog is not in pain during the seizure and is not conscious.
2. Time the seizure. Use your phone's stopwatch. This is the single most important thing you can do. Duration determines whether it's an emergency.
3. Clear the area. Move furniture, sharp objects, and anything your dog could injure itself on. If your dog is near stairs, gently slide them away.
4. Do NOT restrain your dog. Holding the dog down will not stop the seizure and increases the risk of injury to both of you.
5. Do NOT put your hands in or near the dog's mouth. Dogs cannot swallow their tongues. You will be bitten — the jaw muscles contract with tremendous force during a seizure.
6. Do NOT put anything in the dog's mouth — no spoons, no towels, nothing.
7. Dim the lights and reduce noise. Bright lights and loud sounds can intensify seizure activity.
8. Record video if possible. This is enormously helpful for your veterinarian to determine the seizure type.
9. Note the time the seizure ends. If it exceeds 5 minutes, go to the emergency vet immediately.

The Post-Ictal Phase

After the seizure ends, your dog enters the post-ictal phase — a recovery period that can last from a few minutes to several hours. During this phase, your dog may:

• Appear dazed, confused, or disoriented
• Pace restlessly, walk into walls, or seem blind (temporary post-ictal blindness)
• Be excessively hungry or thirsty
• Pant heavily
• Appear clingy and seek comfort, or alternatively be withdrawn and unresponsive
• Have temporary weakness or difficulty walking, especially in the hind legs

This is all normal. Stay with your dog, speak in a calm, reassuring voice, offer water when the dog is alert enough to drink safely, and keep the environment quiet and dark. Do not force food or water. Most dogs return to normal within 1–2 hours, though some dogs have post-ictal phases lasting up to 24 hours.

Causes of Seizures

Idiopathic Epilepsy

Idiopathic epilepsy is the most common cause of seizures in dogs between 1 and 5 years of age. “Idiopathic” means no structural or metabolic cause can be identified — the brain is structurally normal, but its electrical activity is abnormal. There is a strong genetic component. Breeds with high rates of epilepsy include Labrador Retrievers, Golden Retrievers, German Shepherds, Beagles, Belgian Tervurens, Keeshonds, Vizslas, and Border Collies. Idiopathic epilepsy is a diagnosis of exclusion — made after other causes have been ruled out.

Toxin Exposure

Many common household substances can trigger seizures in dogs:

• Xylitol (sugar-free sweetener) — causes hypoglycemia which triggers seizures
• Chocolate and caffeine — theobromine is a seizure-inducing stimulant
• Rodenticides (bromethalin-based rat poison) — causes brain swelling and seizures
• Slug/snail bait (metaldehyde) — one of the most common causes of toxin-induced seizures
• Certain human medications — antidepressants, ADHD medications, pseudoephedrine
• Marijuana/THC — increasingly common with edibles
• Certain flea/tick products — organophosphate-based products can trigger seizures, especially in small dogs

If you suspect toxin exposure, bring the packaging to the emergency vet. Time is critical.

Structural Brain Disease

Brain tumors, encephalitis (brain inflammation from infections like distemper, Neospora, or tick-borne diseases), hydrocephalus, and traumatic brain injury can all cause seizures. Structural disease is more likely when seizures begin in a dog younger than 1 year or older than 5 years. Advanced imaging (MRI) and cerebrospinal fluid analysis are typically needed for diagnosis.

Metabolic Causes

• Liver disease (hepatic encephalopathy) — when the liver can't filter toxins, they accumulate and affect the brain
• Hypoglycemia — dangerously low blood sugar, especially in toy breed puppies or diabetic dogs receiving too much insulin
• Kidney failure — uremic toxins can trigger seizures in advanced kidney disease
• Electrolyte imbalances — severe sodium, calcium, or potassium abnormalities
• Heatstroke — dangerously elevated body temperature damages the brain

When It's an Emergency

Go to the emergency vet immediately if:

• A seizure lasts longer than 5 minutes (status epilepticus)
• Your dog has multiple seizures in a 24-hour period (cluster seizures)
• Your dog does not fully regain consciousness between seizures
• It is your dog's first seizure ever
• Your dog has a seizure and you know or suspect toxin exposure
• Your dog is having difficulty breathing after the seizure
• The seizure occurs in a dog with a known health condition (liver disease, diabetes, cancer)

Diagnosis

After your dog's first seizure, your vet will perform a systematic workup to identify the cause:

• Complete blood count and chemistry panel — checks for metabolic causes (liver, kidney, blood sugar, electrolytes)
• Bile acids test — evaluates liver function, especially important in young dogs (portosystemic shunt)
• Blood pressure measurement — severe hypertension can cause seizures
• Infectious disease testing — tick-borne diseases, distemper, fungal infections
• MRI of the brain — the gold standard for identifying structural lesions (tumors, inflammation, malformations)
• Cerebrospinal fluid analysis — evaluates for encephalitis and meningitis
• Electroencephalogram (EEG) — records brain electrical activity, though availability is limited to specialty centers

Treatment and Medication

Not every dog that has a seizure requires medication. Veterinarians generally recommend starting anticonvulsant therapy when:

• Seizures occur more frequently than once every 6–8 weeks
• Seizures are increasing in frequency or severity
• The dog has had cluster seizures or status epilepticus
• A structural brain lesion has been identified
• Post-ictal periods are severe or prolonged

Common anticonvulsant medications include:

• Phenobarbital — the oldest and most widely used anticonvulsant in dogs; effective in about 60–80% of epileptic dogs; requires periodic blood level monitoring and liver value checks
• Potassium bromide (KBr) — often used in combination with phenobarbital or as an alternative in dogs with liver disease; takes 3–4 months to reach therapeutic levels
• Levetiracetam (Keppra) — a newer anticonvulsant with fewer side effects; available in regular and extended-release formulations; commonly used as an add-on medication
• Zonisamide — another newer option with a good safety profile; useful in dogs that don't respond adequately to phenobarbital

Critical: Once started, anticonvulsant medication must never be stopped abruptly. Sudden discontinuation can trigger severe rebound seizures, including life-threatening status epilepticus. Dosage changes must always be gradual and under veterinary supervision.

Living with an Epileptic Dog

• Keep a seizure log — record the date, time, duration, and character of every seizure; note any potential triggers (stress, missed medication, storms)
• Give medication on a strict schedule — consistency is crucial for maintaining therapeutic drug levels
• Never skip doses — use phone alarms as reminders
• Keep rescue medication on hand — your vet may prescribe rectal or nasal diazepam for use during prolonged seizures or clusters at home
• Maintain regular blood work — monitor drug levels and organ function every 6–12 months
• Swimming safety — epileptic dogs should never swim unsupervised, as a seizure in water can cause drowning
• Block access to stairs and pools — a seizure near these areas is dangerous

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