One moment your dog is happily doing dog things. The next, they collapse, stiffen, twitch, or start paddling their legs.

Few things make a pet parent's heart race quite like a seizure.

Seizures are caused by abnormal electrical activity in the brain, but they aren't a diagnosis themselves. They're a symptom, and figuring out why they happened matters.

Here are five common causes worth knowing.

1. Idiopathic Epilepsy: When There Isn't an Obvious Cause

Sometimes vets investigate and can't find an underlying disease or trigger. That's when idiopathic epilepsy may be considered.

It often:

• Begins in younger to middle-aged dogs
• Has a genetic component in some breeds
• Causes recurring seizures
• Leaves dogs appearing completely normal between episodes

Diagnosis usually involves ruling out other causes first.

The good news? Many dogs with epilepsy live happy, active lives with appropriate monitoring and, when necessary, medication.

2. Toxins & Accidental Poisoning

Dogs have many wonderful qualities.

Pausing to ask, "Should I eat this?" isn't always one of them.

Substances that can potentially trigger tremors or seizures include:

• Certain human medications
• Xylitol
• Some pesticides
• Certain toxic plants
• Excessive amounts of chocolate
• Other household chemicals and toxins

If you suspect poisoning, don't wait for symptoms. Contact your veterinarian promptly and, if possible, keep the packaging or take a photo of whatever your dog may have eaten.

3. Underlying Health & Metabolic Problems

Sometimes the problem isn't actually starting in the brain.

Changes elsewhere in the body can disrupt normal brain function. Possible causes include:

• Low blood sugar, particularly in puppies and some small dogs
• Liver disease
• Kidney disease
• Significant electrolyte abnormalities

This is why bloodwork is often one of the first steps after an unexplained seizure.

A blood sample may not look as impressive as a brain scan, but it can reveal a lot.

4. Brain Disease, Injury & Inflammation

When seizures suddenly develop, especially in an older dog, your veterinarian may want to investigate the brain itself.

Potential causes include:

• Brain tumors
• Head injuries
• Brain infections
• Inflammatory neurological diseases

That doesn't mean an older dog having a seizure automatically has a brain tumor.

Your vet will consider age, medical history, seizure patterns, and neurological examination findings. Advanced testing, such as an MRI or cerebrospinal fluid analysis, may sometimes be recommended.

5. Medications & Drug Reactions

Medications help our pets every day, but adverse reactions and accidental overdoses can occasionally cause neurological symptoms.

Tell your veterinarian about everything your dog receives, including:

• Prescription medications
• Supplements
• Flea and tick preventatives
• Recently administered treatments

Some flea and tick products in the isoxazoline class carry warnings about neurological adverse reactions, including tremors and seizures.

This doesn't mean they're unsafe for every dog. However, dogs with a seizure history may need an individualized conversation with their vet about parasite prevention.

Never stop prescribed medication without speaking with your veterinarian first.

Frequently Asked Questions

What does a seizure in a dog look like?

Not every seizure involves dramatic full-body shaking.

A generalized seizure may cause:

• Collapse
• Body stiffening
• Jerking or twitching
• Paddling of the legs
• Drooling
• Loss of awareness

Focal seizures can be much subtler. You might notice facial twitching, staring into space, repetitive movements, or unusual behavior.

If something looks strange and you're unsure whether it's a seizure, recording a video can be extremely helpful for your veterinarian.

What should I do while my dog is having a seizure?

First, time the seizure. It can feel much longer than it actually is when you're frightened.

Move nearby furniture and dangerous objects away so your dog doesn't injure themselves. Reduce noise and stimulation where possible.

Don't restrain your dog or put your fingers or anything else in their mouth. Dogs don't swallow their tongues during seizures, and you could be accidentally bitten.

If it's safe, record a short video for your veterinarian.

When is a seizure an emergency?

A seizure lasting or approaching five minutes should be treated as an emergency. Multiple seizures occurring close together can also become dangerous and require urgent veterinary attention.

A first-time seizure should be discussed promptly with your veterinarian, even if your dog seems perfectly normal afterward.

Also seek urgent help if you suspect poisoning, your dog was recently injured, or they aren't recovering normally after the episode.

Can flea and tick medication cause seizures?

Neurological adverse reactions, including tremors and seizures, have been reported with some flea and tick medications, particularly products in the isoxazoline class.

That doesn't mean every dog should avoid these medications.

If your dog has epilepsy or a history of seizures, tell your veterinarian before choosing a parasite preventative. They can help weigh the benefits and potential risks and recommend an appropriate option.

Can a dog have one seizure and never have another?

Yes.

A single seizure doesn't automatically mean your dog has epilepsy. It may be related to an underlying illness, toxin exposure, metabolic disturbance, or another temporary problem.

Sometimes no obvious cause is found.

Either way, a first seizure deserves veterinary attention so your vet can determine whether further testing or monitoring is needed.

Are seizures painful for dogs?

During a generalized seizure, dogs usually have altered or lost awareness and aren't thought to experience the event in the same way they would while fully conscious.

The period afterward can be confusing, though.

Dogs may temporarily be:

• Disoriented
• Restless
• Exhausted
• Very hungry or thirsty
• Unsteady on their feet

Give your dog a quiet, safe place to recover and follow your veterinarian's advice.

Can dogs live normal lives with seizures?

Absolutely.

The outlook depends on what's causing the seizures, how frequently they occur, and how well they respond to treatment.

Many dogs with well-managed seizure disorders continue enjoying walks, playtime, naps in ridiculous positions, and all their usual dog activities.

One Seizure Is Worth Paying Attention To

Once your dog is safe, gather as much useful information as you can:

• Time the seizure.
• Record it if it's safe.
• Note what happened beforehand.
• Write down anything unusual your dog may have eaten.
• List recent medications and preventatives.

Then speak with your veterinarian.

Finding the why is what helps determine what happens next.

And hopefully gets your pup back to the much less alarming business of simply being a dog.

Visit Dr. Jeff Werber’s Instagram account (@werbs_dvm) to view and submit questions and answers on weekly AMAs – or call and leave a voicemail at 424-835-0576. Your call will be returned posthaste. For emergencies, download Dr. Jeff Werber’s app Airvet, a video-chat option for veterinary needs at any time of day or night!