Dog Seizures: Causes and Treatments

Significant clues include the age of onset, the dog's breed, and his response to treatment.


There are few things as frightening as watching your dog have a seizure. Yet seizure disorders are surprisingly common in canines. A seizure is defined as uncontrolled electrical activity in the brain. Seizures can run the gamut from very minor, focal seizures (a twitching of the face or a leg) to major convulsions in which a dog loses consciousness, may vocalize loudly, has uncontrolled muscle movements, and loses bowel and/or bladder control.

Types of Dog Seizures

A seizure or “ictus” is comprised of three phases. The pre-ictal phase can begin as much as 24 hours before a seizure and is not always obvious. Your dog may act strange during this period, but this is usually only recognized in retrospect. The second phase is ictus (the seizure itself). In the third, or post-ictal period, your dog is recovering from the seizure. It can be stressful and disturbing to witness, and it varies significantly between dogs. The post-ictal stage can include a deep sleep that lasts several hours to an entire day, confusion, and abnormal behavior, including ravenous hunger or complete anorexia, dilated pupils, and in some cases, blindness that will resolve. Your dog may be disoriented for a short time, but this period is otherwise not dangerous.

dog getting MRI

In the past, seizures have been categorized as grand mal (French meaning “great sickness”) or petit mal (“small sickness”). These terms are no longer used to describe seizure activity, as they are considered too vague. The more recent classifications are tonic-clonic, clonic, and tonic. Seizures can also be described as generalized, focal, or psychomotor.

In a tonic-clonic seizure, the first, very short phase is the tonic. The dog will suddenly stiffen and collapse if standing. Next is the clonic phase, in which the muscles contract and relax rapidly. This is the type of seizure with which most people are familiar. It is often called a convulsion and represents the most common, generalized seizure type in dogs.

A tonic seizure is usually brief (less than one minute) and involves a sudden stiffening of the muscles. This is a less common manifestation of a seizure disorder. A clonic seizure is rhythmic muscle jerking that generally starts in one area of the body. It is very rare and often associated with canine distemper virus. Both a tonic seizure and a clonic seizure can be generalized or focal.

Psychomotor seizures often manifest as unusual behavior, such as “flybiting” at the air or staring into space and not responding to cues. Sometimes, they are called “absence spells,” as the pet seems unaware and unresponsive to his surroundings.

Seizures can last from seconds to hours. When a seizure doesn’t stop after a few minutes, it is called status epilepticus. In this scenario, the body temperature will start to go up due to the repeated muscle contraction, and heat stroke can result. A dog’s body temperature can elevate to as high as 110 degrees or more if the seizure is not interrupted. Prolonged hypoxia (low oxygen) to the brain due to seizures can also cause damage. Status epilepticus is always an emergency.

Medical Emergency: Status Epilepticus

Status, as it’s commonly called, occurs when a seizure persists and will not stop without medical intervention. This is always an emergency and requires veterinary attention. Benzodiazepines like Valium will be given intravenously to stop the seizure. Your dog may need to be cooled to prevent heat stroke. He may need to stay on a continuous infusion of medications like Propofol (an anesthetic) to break the seizure cycle and allow recovery. This can take two to four days in some cases. The prognosis is guarded for recovery.

dog vet check in

Dog Seizure Causes and Diagnostics

Causes of seizures can be divided by age group:

Dogs Less Than Six Months

A dog of this age with sudden onset of seizures likely has a congenital problem, infection with parasites such as Neospora, infection with a virus such as canine distemper or rabies, or toxin exposure. Epilepsy at this age is extremely rare.

The first step of evaluation is, as always, a thorough history. Puppies are prone to ingesting toxic substances such as rat baits and gum sweetened with xylitol. As a result, if your puppy presents with seizures, your veterinarian will recommend a thorough diagnostic work-up. This will start with a complete blood count (CBC) and chemistry panel, urinalysis, and fecal examination.

Bloodwork will evaluate for metabolic causes of seizures, such as liver failure, electrolyte abnormalities, or low blood sugar. A urinalysis will help determine how the kidneys are functioning, as well as look for evidence of any inflammation or infection within the urinary tract. Your vet may also recommend specific blood tests to rule out parasites such as Neospora caninum and Toxoplasma gondii.

If those tests do not reveal a cause, your vet will refer you to a specialist for a cerebrospinal tap and imaging of the brain such as an MRI or CT scan. Because epilepsy is very rare in dogs this age, it is important to find the cause of the seizures. Without definitive diagnosis, the underlying condition is likely to worsen, as are the seizures.

If further testing is not financially possible, your veterinarian will start empirical treatment based on the suspected underlying cause. This may or may not be effective.

Dogs Aged Six Months to Five Years

Epilepsy becomes the most likely diagnosis in this age group when other causes are excluded. Epilepsy is not a disease per se. It is a description of seizure activity for which no underlying cause can be found.

A diagnosis of epilepsy cannot be made definitively until every other cause of seizures is ruled out. The tests needed to rule out an underlying cause can be expensive, however, so this diagnosis is often made based on breed, clinical signs, and response to treatment. Beagles, Schnauzers, Collies, Cocker Spaniels, and Basset Hounds are predisposed to epilepsy.

Your veterinarian will recommend the same set of diagnostic tests as for puppies and likely add a blood pressure measurement, thyroid levels, and x-rays of the chest and abdomen. If those are normal, the next steps are imaging of the brain as outlined above. In most cases, owners do not opt for the advanced testing and instead treat the suspected epilepsy with anti-epileptic drugs (AEDs).

Dogs Older Than Five Years

In dogs older than five, the most common cause of seizures is a brain tumor. These are generally benign tumors, such as meningiomas. Seizures can result from the tumor pressing on nearby structures as well as from swelling around the tumor.

The same diagnostic algorithm is followed as above, and again, many owners opt to merely treat the seizures without an in-depth exploration of the causes. While brain tumors are generally benign and can be removed via surgery, they are invasive and carry a guarded prognosis for recovery.

The causes of seizures are vast and varied. They can be broadly divided into extra-cranial (outside the brain) and intracranial (inside the brain).

Extra-cranial diseases include metabolic disease such as liver failure, toxin ingestion like xylitol or bromethalin rat poison, insulinoma (a tumor of the pancreas causing low blood sugar), infectious diseases like rabies and canine distemper virus, parasitic infection, and electrolyte derangements.

Intracranial causes are almost as varied and include cancer, inflammatory conditions such as necrotizing encephalomyelitis, previous head trauma leading to scar tissue formation within the brain, and vascular abnormalities like blood clots.

Dog Seizure Treatments

The first step in treatment may be nothing at all. If seizures are short and not frequent, treatment may not be necessary.

While they are difficult to witness, if the seizures are brief (under five minutes) and self-limiting, then they are not dangerous to your dog. In this case, your veterinarian may not prescribe medication but simply have you keep a “seizure journal.” This involves writing down when the seizures happen, what could have precipitated them (stress, anxiety, sleep), how long it lasted, and how long it takes your pet to recover. Your veterinarian will use this log to help dictate when to start treatment and what treatment to start.

In 2016, the American College of Veterinary Internal Medicine (ACVIM) released a consensus statement regarding when to start AED therapy. In general, if the seizures are mild and infrequent, therapy is not recommended. If they are severe and frequent, or the dog has a history of previous head trauma, or if there is an obvious lesion on CT/MRI (such as a brain tumor), AEDs should be started.

If the seizures are becoming a problem, medication is the first step. There are four commonly used AEDs in veterinary medicine, but more drugs are currently under study and are tentatively being used.

The most commonly prescribed first-line medication is phenobarbital, although this is slowly changing. “Pheno,” as it is frequently called, has long been used to treat seizures in humans and animals, so the effects and side effects are well-known, and the drug is readily available and inexpensive. It is also very effective. Unfortunately, it does have side effects such as sedation, weight gain, panting, increased appetite, and increased liver enzymes.

Phenobarbital is usually given twice a day and is a controlled substance under FDA regulations. It should not be stopped abruptly, as this can lead to more seizures. If you start administering this drug to your dog, make sure you are always prepared with refills before you run out! This will require at least a yearly examination with your veterinarian to maintain a valid client-patient relationship (VCPR).

Your veterinarian will also recommend monitoring of liver values and phenobarbital levels, likely on a bi-annual or annual schedule. This will help determine the effects that phenobarbital is having on your dog’s body. It will also assist your veterinarian in determining how much more (or less) phenobarbital your dog can receive.

About 30 percent of dogs will achieve good seizure control on phenobarbital. Greater than 75 percent will have a significant reduction in seizure frequency. About 30 percent of dogs will require an additional drug to control their seizures.

Historically, potassium bromide has been the next drug of choice. This is changing, as more and more veterinarians are becoming comfortable with and using newer AEDs. Potassium bromide also causes sedation and can be associated with pancreatitis, as well as a condition called bromism (bromide toxicity). It is being used less as newer drugs replace it.

The two newest AEDs are levetiracetam (Keppra) and zonisamide (Zonegran). Keppra has been used in humans in the U.S. for the past 10 years. It has very few known side effects and does not damage the liver. It is safe to use in patients with compromised kidney or liver function and does not generally cause drowsiness. It requires dosing every eight hours and can be expensive for larger dogs. An extended release formulation is sometimes available and can be given twice a day. It is also less cost effective. Unfortunately, there are few studies to evaluate how well it works in canines, so Keppra’s use is currently anecdotal. As time passes, there will likely be more evidence for its usage, more generics available, and a twice-daily formulation will become readily available.

Zonisamide is similar to Keppra. How it works to prevent seizures is not clear. It has possible side effects of sedation, decreased appetite, ataxia (wobbly walking), and might contribute to liver and urinary problems, though this has not been proven. It is also given twice a day.

In some cases, one drug can control seizure activity. In others, multiple seizure medications are needed.

Recently, a veterinary therapeutic diet was released by Purina that may significantly improve seizure control when given with medications. This diet uses medium chain triglycerides (MCTs) as the fat source. These MCTs have an anti-seizure effect and can improve control in conjunction with medication therapy.

Your veterinarian may send you home with an anti-seizure medication to apply into the rectum or nostrils if your dog has a seizure.

There are other, less mainstream treatment options such as vagal nerve stimulator implants. These are not commonly done and are only used in the most refractory cases.

Catherine Ashe is a 2008 graduate of the University of Tennessee College of Veterinary Medicine. After nine years in emergency medicine, she now works as a relief veterinarian in Asheville, North Carolina.


  1. Gaile, I have experienced the same with my small rat terrier. She has begun having episodes where she stiffens, falls down and cannot move. It only lasts a minute, then she seems to be fine. She has also been wheezing and gagging, unsure of cause or connection. During these episodes, my other dogs appear to prepare to attack her. I have to watch them very closely and keep her separate from the others if they will be unsupervised.
    A couple of times prior to the start of these episodes, she woke me up from a sound sleep with a very weird vocalization. I thought at that time she was just dreaming. Now I wonder if this was the beginning of whatever is wrong with her. She hasn’t made any sounds during these recent seizures, only the wheezing/gagging which isn’t always followed by a seizure.

    • My dog had a seizure for the first time a few weeks ago and then another one last week. Each time he was doing the wheezing/snorting/gasping for air thing and also he was gagging like he was trying to throw up but nothing was coming out. Scared the s!@t out if me. I’m also wondering if there is a connection. I was thinking maybe he couldn’t breath and there lack of oxygen to his brain made him have a seizure. I’m relieved a little too know it happened to someone else too. I hope your fur baby is better. I’m about to make another vet appointment right now.

      • Brenda & Emilio – first off I hope both of your dogs are healthy and doing well!

        I’m curious if your dog is still having seizures? Did the vet ever diagnose anything?

        Our dog has had 5 seizures in the past 7 or 8 months, and all of them have started with him gagging/trying to cough something up with nothing coming out which then turns into convulsions. It’s hard to tell if the gagging is the start of the seizure or if the seizure happens as a result of the gagging.

        Wondering if you’ve come across any solutions / reasons for this. Our vet has tested his blood pressure as suggested by Aaron below along with many other tests/scans and they’ve all come back normal. Any information you might have would be very helpful!

        • My 9 year old yorkie has been suffering from seizures lately and it all started with him gagging from time to time a few months back. I would also love to hear back from anyone who has more information on this. 🙁

  2. Good day,

    We got a puppy and everything went very well.
    The day she got her 3 vaccination she started having fits.
    The vet told me that the vaccination make some dogs sick during the first week.
    Never in my life have I experienced this.
    The fits are still happening and it is almost three weeks after her last vaccine.

    She had a very bad fit where she lost complete control over her body.
    Please note that she is only 15 weeks old.
    Can this be because of the vaccination?
    I had a talk with the breeder and there is no known record of any of this.

    I can not afford expensive treatments.

    Please help me.

  3. My little dog has been having sezuires over 5 yrs.shes on 3 different meds.on a greenbean diet and treats set off seizures so she cant have.Her vets are excellent but the meds or bbloodwork aint cheap.It has been said to me maybe a brain tumor.her eye lids turn blood red when she has bad i have to insert meds in her hindend when she seizes to stop them.Shes a fighter and still as sweet as ever.eye sight not 100%.

  4. My 13 year old lab had his first seizure 1/2/20. He was good all day then at 7 that night it all started. I had given him his nexguard that morning which he’s taken forever. Vet thought could be that Or tumor, bloodwork was good he was a little anemic. We are having to monitor him for next two weeks . Then vet gonna check blood again. He is on supplement for the anemia plus chicken liver . He had two more seizures on Friday.Then threw up something Saturday morning that didn’t look like anything he was fed.. since then no seizure…thank goodness.. but very unsteady when standing when he’s walking he does ok then maybe he will trip.. Eats fine and poops good.. I did take sample of that throw up to vet he had no clue as to what it was.

  5. My dog is 2 years old. He started to have slight seizures when he was about a year old. He has now had about 8 or 9 of them and the one he had tonight was very scary. We will be taking him in for bloodwork again as this one was over 5 minutes long. And in response to someone who wrote in an earlier comment, the vet had instructed us to watch any of the other dogs around him (my daughter has 2 pit bulls-very nice dogs), I guess the dog having the seizure gives off some sort of scent or something that the other dogs will attack them. Even if they are the best of friends, which my little poodle/fox terrier and her first pit bull are the best of friends. I saw this happen to a family who had 2 older dogs (both over 10 years old w/ same family). They were gone when it happened and they didn’t understand how that could happen, because both dogs were so mild mannered. They ended up putting down the dog who had killed his friend not knowing that the other day may have had a seizure.

  6. Its horrible to see our furry babies go through this, I cry every time it happens to my 4yr old yorkie. She doesn’t have them to often, thank God, her bloods are fine. I just have to keep a log and record the siezers or fits if possible, as it helps to show the vet, I know that is the last thing on our minds when they are suffering . Good luck everyone.

    • My 7 year old chihuahua just had one for the first time a few weeks ago. It’s so frightening, I was in tears, I’ve never seen this happen to a dog before.
      We’re in lockdown at moment, so vets aren’t open as normal.
      He’s normally very healthy, has regular checks and vaccinations etc.

      • Over Vaccinating is usually the problem, as well as flea and tick treatments. Vaccinations are not necessary after the age of 4 or 5 years old. And flea and tick treatments cause neurological problems to include seizures. Even if you have given that treatment in the past with no problem.

  7. Our four year old poodle mix, Rescue, had her first seizure Oct 2018, another Nov 2019, at the end of February she had her Vaccinations, had two seizures the next morning, took her to vet, did bloodwork, everything looked ok, last night had her worst seizure, and had another this morning, my question would this amount Constitute putting her on Medication.. Phenobarbital, or has anyone ever heard of controlling seizure with CBD oil

    • my son in law tried hemp oil for his chihuahua cross and did not stop seizures completely and neither did the medication he used and I don’t know the name of that med. His seizures were severe and lasted several minutes.

    • Yes! You’ll need to make sure it’s a FULL SPECTRUM CBD. Make sure it’s specific for dogs. You don’t want any THC in it at all. Find one that is reliable in the amount per dose, per treat and you can also find the oil to give direct or in their food, if they will eat all of their food. It is not the same as a regular hemp product. Dogs respond differently. It can help to reduce the amount of seizures and also the intensity of them. Combine this with a dog food that is geared to support the brain. It’s costly, though a solid solution for us… at least it has been this past year. Zero seizures since trying these two things, in addition to preventing triggers for seizures.

    • Yes Barbara. My dog has seizures. They were coming once a month and then he had one two weeks apart. A friend got me full spectrum CBD. It has definitely helped! Unfortunately he had a seizure last night, but hasn’t had one until now, since 11th April. So most definitely this oil is helping him

  8. My 5 year old terrier had at least 2 petit mal seizures following having been given a monthly chewable flea prevention medication. Then I read the label: may cause seizures!! No more of that stuff for him. I am still angry that it was prescribed for him.

  9. Well, I‘ve found something that does have a temporary relief from symptoms that comforts them immediately. I have 4 dogs with “white dog shaker symptoms “,
    They are Maltese mix and all but 1 are symptomatic. I thought of the idea after seeing the movie about the girl who is Autistic and helped out with cattle stress. So, they still are with some symptoms but went through the episode very calmly. At this point, I am currently thinking about how to market this piece of gadget.

  10. try a salmon formula dog food.had my pitbull on a salmon formula 8 ingredients for years took him off of it and started having seizures put him back on and they went right away. it’s the omega 3 n 6 vitamins

  11. I had a beautiful Siberian husky he was only 6 but sadly passed away on the 7 April it was his 3rd seizure and it was a bad one .he was on medication. But it did not help him and sadly he was put to sleep and we were on lockdown so we could not be there with him saddest day of my life miss him so much