Seizures in Dogs

Written by Dr Leigh Davidson BVSc, BApplSc

Causes, Emergency Signs, Diagnosis and Treatment

Seeing your dog suddenly collapse and have a seizure can be incredibly frightening.

During a seizure, the body may stiffen, the legs may paddle, and your dog may appear unaware of what is happening. Some dogs salivate, chew their jaws or lose bladder control.

After the seizure stops, they often appear confused, restless, or temporarily disoriented while the brain returns to normal function.

Although the episode may appear dramatic, a seizure does not always have the same medical meaning.

Some dogs experience a single seizure and never have another. Others develop epilepsy, while in some cases seizures occur because of an underlying condition affecting the brain or the body.

The most important step is understanding when a seizure requires urgent veterinary care and when it can be investigated more calmly.

Age, seizure duration, recovery time and the dog’s overall health all provide important clues.

In this guide, we will explain:

• What seizures are and why they occur
• When a seizure is an emergency
• The most common causes of seizures in dogs
• When medication is needed and when it may not be
• How blood tests and MRI scans help with diagnosis

Understanding these factors can help you respond calmly and make informed decisions about your dog’s care.

When Is A Dog Seizure an Emergency

A dog seizure is an emergency if it lasts longer than five minutes, occurs repeatedly, or your dog does not recover normally afterwards.

Not all seizures require immediate treatment, however some situations are life-threatening and require urgent veterinary care.

Seek emergency veterinary attention if:

• The seizure lasts longer than five minutes
• Your dog has more than one seizure in a 24 hour period
• Multiple seizures occur close together (cluster seizures)
• Your dog does not regain normal awareness after the seizure
• There are breathing difficulties, collapse, or severe weakness
• Toxin exposure is suspected

Veterinarians refer to prolonged seizures as status epilepticus and repeated seizures as cluster seizures.

These conditions can lead to overheating, reduced oxygen to the brain, and permanent injury.

If any of these signs are present, your dog should be taken to an emergency veterinary hospital immediately.

If you are unsure whether the seizure requires urgent treatment, speaking with an online vet can help determine the safest next step.

When Can a Dog Seizure Be Monitored at Home?

Many seizures are short and self-limiting.

If a seizure lasts less than two minutes and your dog recovers normally afterwards, it may not require an emergency trip to the vet.

However, the event should still be discussed with your veterinarian.

If your dog has a seizure at home:

• Time the seizure
• Record a video if possible
• Keep your dog safe from stairs or furniture
• Avoid putting your hands near their mouth
• Allow your dog to recover in a quiet environment

Keeping a seizure diary is incredibly helpful when deciding whether treatment is necessary.

What Is A Seizure in Dogs?

A seizure occurs when abnormal electrical activity spreads through the brain.

Normally, brain cells communicate through carefully controlled electrical signals.

During a seizure, these signals become excessive and synchronised, disrupting normal neurological control.

According to the Merck Veterinary Manual, seizures represent sudden abnormal electrical activity in the brain that produces involuntary muscle activity, behavioural changes or loss of consciousness. (Merck Veterinary Manual, 2024)

Typical signs of seizures in dogs include:

• Collapse
• Stiffening of the limbs
• Paddling movements
• Jaw chomping
• Drooling or salivation
• Urination or defecation

Most seizures last between 30 seconds and two minutes.

After the seizure stops, dogs often enter what veterinarians call the post-ictal phase.

During this time, they may appear confused, disoriented, restless or temporarily blind while the brain returns to normal function.(Podell et al., 2016)

What Causes Seizures in Dogs

Seizures generally occur for one of three reasons.

Reactive seizures

Reactive seizures occur when a problem elsewhere in the body affects brain function.

Examples include:

• Low blood sugar
• Liver disease
• Electrolyte disturbances
• Toxin exposure

If the underlying condition is corrected, the seizures may stop.

Structural Brain Disease

Seizures may also occur when there’s a disease within the brain itself.

Possible causes include:

• Brain tumours
• Inflammatory brain disease
• Traumatic brain injury – head trauma
• Congenital abnormalities

These conditions often require advanced diagnostic testing.

Idiopathic epilepsy

Idiopathic epilepsy is the most common cause of seizures in young healthy adult dogs.

The International Veterinary Epilepsy Task Force defines idiopathic epilepsy as recurrent seizures with no structural or metabolic cause identified.

Dogs with epilepsy are usually normal between seizures.(Bhatti et al., 2015)

Why Age Matters When Diagnosing Seizures

Age of onset is one of the most useful clues about the likely cause.

Dogs Under Four Years

In young dogs, idiopathic epilepsy is the most common cause of recurrent seizures (*see section about puppies).

Dogs are usually neurologically normal between episodes.

Dogs Older Than Eight Years

When seizures begin in older dogs, veterinarians become more concerned about brain tumours or structural brain disease.

This does not mean every older dog with seizures has a tumour, but the probability increases with age.

Dr Leigh Says
Age of onset is one of the most useful clues when evaluating seizures. Young adult dogs often develop idiopathic epilepsy, while older dogs require a more in-depth investigation for brain disease.

Seizures in Puppies

When seizures occur in very young dogs, especially under six months of age, veterinarians consider congenital or developmental problems more strongly than epilepsy.

In these cases, the brain or body may not have developed normally, which can affect how the brain functions.

Common causes of seizures in puppies include:

Congenital Liver Shunts

A portosystemic shunt is one of the most common congenital causes of seizures in young dogs.

Blood from the digestive system bypasses the liver and goes directly to the bloodstream instead of being detoxified.

As toxin levels build up in the bloodstream, they affect the brain, leading to a condition called hepatic encephalopathy.

Signs may include:

• Seizures
• Poor growth
• Behavioural changes
• Disorientation after eating

Small breeds such as Yorkshire Terriers and Maltese are commonly affected.

Brain Malformations

Some puppies are born with structural abnormalities of the brain.

Examples include:

• Hydrocephalus
• Cortical malformations
• Cerebellar abnormalities
• Hydrocephalus, where fluid accumulates within the brain, is seen more commonly in toy breeds and brachycephalic dogs.
• Metabolic disorders

Young animals may also develop seizures from metabolic abnormalities such as:

• Low blood sugar (hypoglycaemia)
• Electrolyte imbalances
• Severe infections

Toy breed puppies are particularly prone to hypoglycaemia, which can trigger seizures if blood glucose drops too low.

Infectious Diseases

Certain infections can infect the brain and cause seizures in young dogs.

These include inflammatory or infectious diseases of the central nervous system.

Viral:

• Canine distemper virus (CDV)
• Rabies
• Occasionally Herpesvirus and Adenovirus

Parasitic/Protozoal Infections:

• Neospora caninum (Neosporosis)
• Toxoplasma gondii (Toxoplasmosis)
• Baylisascaris (Raccoon roundworm – not present in Australia)

Bacterial Infections:
Any that can cause meningitis or encephalitis – often spread from infections in the ear, sinus or bloodstream.

• Streptococcus
• Tick-Borne diseases eg. Ehrlichia, Lyme Disease, Rocky Mountain Spotted Fever

Fungal Diseases:

• Cryptococcos
• Blastomycosis
• Coccidiodomycosis (Valley Fever)

Dr Leigh says:
When seizures occur in puppies, veterinarians are usually more concerned about congenital or metabolic disease than epilepsy. These cases often require blood testing and sometimes imaging to identify the underlying cause.

Why Early Investigation Matters

Unlike idiopathic epilepsy, which often develops in young adult dogs, seizures in very young puppies frequently indicate an underlying disease that may require treatment.

For this reason, veterinarians usually recommend diagnostic testing earlier in puppies than in otherwise healthy adult dogs with a single seizure.

Conditions That Can Look Like Seizures in Dogs

Not every sudden collapse or abnormal movement in dogs is caused by a seizure.

Several medical conditions can mimic seizure activity, and distinguishing between them can sometimes be difficult without veterinary assessment.

Veterinary neurologists emphasise that video recordings of the episode are often extremely helpful for diagnosis.

Syncope (Fainting)

Syncope occurs when blood flow to the brain temporarily decreases, often due to heart disease or abnormal heart rhythm.

Dogs may suddenly collapse and briefly lose consciousness, but the episode is usually short, and recovery is rapid.

Unlike seizures, fainting episodes typically don’t involve limb paddling and there is little post-episode confusion.

Cardiac disease is a common cause of syncope in dogs and should be investigated when collapse occurs.
(Merck Veterinary Manual, 2024)

Vestibular Episodes

Vestibular disease affects the balance system of the inner ear and brain.

Affected dogs may suddenly lose balance, fall over, or appear dizzy.

These episodes can appear dramatic, but dogs usually remain conscious during the event.

Typical signs include:

• Head tilt
• Loss of balance
• Abnormal eye movements (nystagmus)
• Nausea or vomiting

Because awareness is usually preserved, vestibular disease can often be distinguished from seizures.
(Merck Veterinary Manual, 2024)

Tremor Syndromes

Some neurological disorders cause involuntary shaking rather than true seizures.

Examples include:

• Idiopathic head tremors
• Generalised tremor syndrome

Dogs are usually conscious and responsive during these episodes, which helps differentiate them from epileptic seizures.
(Packer et al., 2018)

Narcolepsy and Cataplexy

These rare disorders cause sudden episodes of collapse or sleep triggered by excitement or activity.

Dogs typically regain normal function quickly after the event.(Podell et al., 2016)

Dr Leigh says:
Video recordings of collapse episodes are often one of the most useful diagnostic tools when evaluating suspected seizures in dogs.

How Seizures Are Diagnosed in Dogs

Diagnosing the cause of seizures involves several steps.

The goal is to determine whether the seizure is caused by epilepsy, a problem elsewhere in the body, or a disease within the brain.(Bhatti et al., 2015)

Veterinarians usually begin with a detailed history and physical examination.

Important information includes:

• The dog’s age when seizures started
• How long the seizure lasted
• How often the seizures occur
• Whether recovery is normal afterwards
• Whether the dog behaves normally between episodes

Video recordings of the episode are extremely helpful and allow the vet to determine whether the event was a seizure or another condition.

Physical and Neurological Examination

A thorough examination helps determine whether the nervous system appears normal between seizures.

Dogs with idiopathic epilepsy typically have a normal neurological exam between episodes.(Podell et al., 2016)

If abnormalities such as weakness, head tilt, circling or vision problems are present, veterinarians become more concerned about structural brain disease.

Blood Tests

Blood tests are usually the first diagnostic step.

These tests help identify reactive causes of seizures, such as:

• Liver disease
• Low blood sugar
• Electrolyte imbalances
• Toxin exposure

Routine blood testing often includes:

• Complete blood count (CBC)
• Serum biochemistry profile
• Electrolyte levels

In young dogs or breeds predisposed to liver shunts, additional testing such as bile acid testing, may be recommended.

Blood tests are also important before starting long-term seizure medications.

Advanced Imaging

If blood tests are normal but seizures continue, veterinarians may recommend imaging of the brain.

Magnetic resonance imaging (MRI) is the preferred method because it provides detailed images of the brain structure.

MRI is most often recommended when:

• Seizures begin in older dogs or puppies
• Neurological abnormalities occur between seizures
• Seizures become more frequent or severe
• Inflammatory brain disease is suspected

MRI can identify conditions such as brain tumours, inflammation or congenital abnormalities.

Cerebrospinal Fluid Testing

In some cases, veterinarians may also analyse cerebrospinal fluid (CSF).

This fluid surrounds the brain and spinal cord and can often help detect inflammatory or infectious diseases affecting the nervous system.

Dr Leigh Says:
Diagnosis of seizures is a stepwise process. Many dogs with epilepsy will have normal blood tests and neurological exams, while dogs with structural brain disease often show abnormalities between seizures.

Should My Dog Have an MRI for Seizures?

MRI (magnetic resonance imaging) is the most accurate way to look for disease inside the brain. It allows veterinarians to see tumours, inflammation, bleeding and structural abnormalities that cannot be detected on standard tests.

MRI is not necessary for every dog that has a seizure and is not always the best use of money.

That distinction matters.

When MRI Is Useful

MRI becomes much more valuable when:

• The dog is older when the first seizure occurs, especially over 6 years
• There are abnormal neurological signs between seizures
• The seizure pattern is severe from the start
• Blood tests do not explain the seizures
• Inflammatory brain disease is suspected
• The owner would pursue different management depending on the result

This is in line with IVETF (International veterinary epilepsy task force) guidelines, which recommend MRI and routine CSF analysis after reactive causes are excluded in dogs with onset under 6 months or over 6 years, neurological deficits between seizures, cluster seizures or status epilepticus at onset, or drug resistance.

What Can an MRI Show

MRI scans can identify several conditions that may cause seizures, including:

• tumours
• inflammation
• malformations – congenital brain abnormalities
• bleeding or stroke
• infections affecting the brain

It can meaningfully change the prognosis.

It can change treatment. For example, a dog with suspected inflammatory CNS disease may need an entirely different plan from a dog with presumed idiopathic epilepsy.

It can stop guesswork.

What Are The Downsides of MRI

Although MRI is extremely useful, it also has limitations.
MRI scans:

• are expensive
• usually require general anaesthesia
• may not always identify the cause of seizures

Sometimes an MRI scan looks completely normal even though a dog is having seizures. In these cases, veterinarians often diagnose epilepsy, which means the brain structure appears normal, but seizures still occur.

When MRI May Not Change Management

In some situations, MRI may not be the best use of money.

This is the nuanced part, and needs to be said clearly.

If an older dog is having first seizures and the owner knows they would not pursue neurosurgery, radiation or advanced referral treatment for a brain tumour, then MRI may offer diagnostic certainty but limited practical benefit. In that case, the money may be better spent on stabilisation, quality of life support, seizure control and thoughtful palliative planning.

Likewise, if the broader history, location and exam do not make infectious or inflammatory disease particularly likely, and the result would not materially alter treatment decisions, MRI may not be the best first spend.

That does not mean MRI is unnecessary medicine. It means value depends on whether the result will change what you do next.

That is the real standard owners need to understand.

The key question is always:
Will the result change what we do next?

If the answer is yes, MRI can be extremely valuable. If the answer is no, other approaches may be more practical.

Veterinary Advice

If your dog (or any pet) has started having seizures and you are unsure whether MRI or further testing is needed, discussing the situation with a veterinarian can help you understand the options and decide what is most appropriate for your dog.

A veterinary consultation can help assess seizure patterns, review video recordings and determine whether advanced imaging is likely to provide useful answers.

Why Treatment Isn’t Always Started Immediately

Many owners expect medication to start after the first seizure. In reality, veterinarians often monitor the situation first.

This is because anti seizure medications are not without side effects.

Common adverse effects include:

• sedation
• increased thirst
• increased appetite
• increased urination
• wobbliness

For some drugs, such as phenobarbital, long term use may affect liver function.

This means that treatment decisions are based on seizure frequency, severity and pattern, type of seizure and tolerability, not simply whether a seizure occurred.

The ACVIM epilepsy guidelines recommend starting long term therapy when seizures become recurrent, cluster seizures occur, or seizure severity increases.(Podell et al., 2016)

Common Seizure Medications

Several medications are used to manage seizures in dogs.

As previously mentioned, the choice of medication depends on the individual dog, including seizure frequency, severity, underlying cause, and response to treatment.

In many cases, treatment is adjusted over time, and some dogs require combination therapy to achieve good seizure control.

Phenobarbital

Phenobarbital is one of the most widely used anti seizure medications in dogs and is often considered a first line treatment.

It is generally effective and affordable.

However, it is metabolised by the liver and may cause hepatotoxicity in some patients. Regular blood tests are required to monitor drug levels and liver function.

Some dogs may experience side effects such as sedation, increased thirst, and increased appetite (with weight gain), particularly when starting treatment.

Levetiracetam (Keppra)

Levetiracetam (Keppra) is commonly used either alone or in combination with other drugs.

It is generally well tolerated and has fewer systemic side effects than phenobarbital.

It is frequently used in dogs with cluster seizures.

For optimal efficacy, it requires dosing three times a day, making it inconvenient for some owners.

Potassium bromide (KBr)

Potassium bromide (KBr) may be used when phenobarbital is not tolerated or when additional seizure control is needed.

It is often used as an add on medication rather than a first choice.

One important consideration is that potassium bromide can take several weeks to months to reach stable levels in the body, so it’s not suitable for rapid seizure control.

Zonisamide

Zonisamide is used in some dogs as either a primary medication or as an add on therapy when seizures are not adequately controlled.

It is generally well tolerated and may require less intensive monitoring than some older medications, although regular health checks are still recommended.

Imepitoin (Pexion)

Imepitoin (Pexion) is licensed for the treatment of idiopathic epilepsy in dogs in some regions.

It is often used in dogs with milder seizure patterns and is generally well tolerated, with a lower risk of sedation compared to some traditional medications.

It may not be as effective in more severe cases, so treatment choice should always be individualised.

Emergency Medication

Medications such as diazepam or midazolam may be used in emergency situations to stop active seizures, particularly in dogs with cluster seizures or prolonged episodes.

These medications are used for short term control and do not replace long term seizure management.

How Veterinarians Choose Seizure Medications for Dogs

There is no single “best” seizure medication for all dogs.

Treatment decisions are based on:

• how often seizures occur
• how severe they are
• the underlying cause
• how the individual dog responds to medication

In many cases, treatment is not straightforward.

Some dogs respond well to the first medication chosen, while others require dose adjustments, medication changes, or the addition of a second drug to achieve adequate control.

Finding the right balance can take time. It often involves ongoing monitoring, repeat blood tests, and close communication with your veterinarian.

For some dogs, seizure management can become complex, time consuming, and expensive, particularly when multiple medications or long term monitoring are required.

Frequently Asked Questions About Seizures in Dogs

How long is too long for a dog seizure?

Most seizures last less than two minutes. A seizure lasting longer than five minutes is an emergency.

Should I go to the vet after my dog has a seizure?

Yes. Even if your dog recovers quickly, a veterinary check within the next 7 days is important to determine the cause.

Can dogs live normal lives with seizures?

Yes. Many dogs with epilepsy live long, happy lives with appropriate treatment and monitoring.

What should I do during a seizure?

Keep your dog safe, avoid their mouth, and time the seizure. Seek veterinary care if it lasts longer than five minutes. Recording the seizure can be helpful.

What This Means for Your Dog

A seizure can be a frightening experience, but it is important to understand that seizures are not a death sentence.
The goal is always to improve quality of life while minimising side effects.

Many dogs with seizures, particularly those with idiopathic epilepsy, go on to live long, happy, and comfortable lives with appropriate management.

The key steps are:

• recognising when a seizure is an emergency
• identifying any underlying cause where possible
• choosing the right treatment plan for your dog

Some dogs will only ever have a single seizure and never require ongoing treatment. Others may need long term medication and monitoring.

In many cases, it can take time to find the right balance of medication. Adjustments may be needed, and some dogs require more than one drug to achieve good control.

While this process can be challenging and sometimes costly, the goal is always the same:

to reduce seizure frequency and severity while maintaining a good quality of life.

With the right approach and veterinary guidance, most dogs with seizures can continue to enjoy a normal routine, good activity levels, and a strong bond with their owners.

If your dog has had a seizure and you are unsure what to do next, speaking with a veterinarian can help you quickly determine whether it is an emergency and what the safest next step is.

References

Bhatti, S. F. M., De Risio, L., Muñana, K., et al. (2015). International Veterinary Epilepsy Task Force consensus proposal for diagnostic approach to epilepsy in dogs. BMC Veterinary Research, 11, 148.
https://doi.org/10.1186/s12917-015-0462-1

Podell, M., Volk, H. A., Berendt, M., et al. (2016). 2015 ACVIM small animal consensus statement on seizure management in dogs. Journal of Veterinary Internal Medicine, 30(2), 477–490.
https://doi.org/10.1111/jvim.13841

Packer, R. M. A., Berendt, M., Bhatti, S., et al. (2018). Epilepsy in dogs and cats: Epidemiology, pathophysiology and clinical management. The Veterinary Journal, 238, 17–23.
https://doi.org/10.1016/j.tvjl.2018.06.002

Merck Veterinary Manual. (2024). Epilepsy and seizure disorders in dogs.
https://www.merckvetmanual.com

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