You’ve likely heard of seizures or epilepsy in people, but epilepsy from an unknown cause is also a condition that affects almost 1% of dogs. Epilepsy is a condition in which the brain repeatedly functions abnormally, resulting in sudden spikes in the brain’s electrical activity that causes twitching, convulsions, shaking, or spasms the dog is unable to stop or control.
“Idiopathic epilepsy is the most common chronic medical neurological condition in dogs,” explains Karen Munana, DVM, DACVIM (Neurology), an epilepsy researcher at North Carolina State University College of Veterinary Medicine.
Its prevalence is much higher in many breeds in which it is thought to have a genetic component.
What Is Epilepsy in Dogs?
Many people use the term seizure and epilepsy interchangeably, but a seizure is the result of the disorder, and can be due to several causes. The causes are divided into three groups:
- Reactive seizures are due to metabolic disorders, high fever, toxins, or other systemic conditions that affect the whole body.
- Structural seizures are due to primary brain problems, such as stroke, brain tumor, brain injury or degeneration.
- Idiopathic epilepsy are seizures not due to the other causes, and subdivided into proven-genetic (breed-related), suspected-genetic, and epilepsy of unknown origin.
The types of seizures can also be categorized into three groups:
- Generalized seizures (formerly called grand mal) involve both halves of the brain, the entire body, and usually involve loss of consciousness. The dog may become stiff, fall over, paddle with the legs, chomp the jaws, shake tremble, vocalize, defecate, and urinate. Most seizures last from 30 to 90 seconds, but they can also last a few minutes. In some cases, the seizure continues even longer, or doesn’t stop, a condition called status epilepticus.
- Myoclonic seizures are generalized seizures in which the dog doesn’t lose consciousness and are usually triggered by something in the environment like flashing lights or sudden sounds.
- Focal seizures (formerly called petit mal or partial) involve only one side of the brain, and patients typically maintain consciousness. They may be so slight they go unnoticed, as though the dog is just twitching a leg, or staring into space chomping their jaws. They may or may not progress to more severe seizures.
Sometimes seizures occur repeatedly. “Approximately half of dogs with idiopathic epilepsy have cluster seizures (defined as two or more seizures within a 24-hour period),” says Munana. “Cluster seizures are associated with a higher risk of death or injury compared to isolated seizures, and are also associated with a decrease in quality of life for both the dog and the caregiver.”
How Is Epilepsy in Dogs Diagnosed?
Seizures can result from causes other than epilepsy, such as brain injuries, brain infections, high fever, toxins, metabolic disorders, low blood sugar, or tumors. Several tests can help rule out some other causes. A standardized epilepsy questionnaire can pinpoint when a seizure is more likely to occur, the dog’s age at first seizure, and other important factors that could point to epilepsy. Generalized epileptic seizures more often occur when the dog is resting or sleeping, while those due to other causes occur equally whether dog is awake or asleep. Knowing whether epilepsy occurs at a higher rate in certain breeds can cause the veterinarian to suspect epilepsy in dogs of some breeds.
It’s sometimes hard to tell if a dog is actually having a seizure versus some type of neural disorder. For example, some dogs have a condition called “idiopathic head bobbing” or “head tremors.” But unlike a seizure, the dogs can usually be distracted away from the behavior and seem alert to their surroundings during it. Other dogs can have episodic neck pain that causes tremors, shaking, and spasms. This can be caused by cervical disk disease or a condition called Chiari-like malformation and syringomelia.
Behavioral Cues of Epilepsy in Dogs
The dog’s behavior just before or after a seizure can help diagnose it as a seizure. After a generalized seizure, the dog may seem groggy or confused. In some cases, these signs can be severe, such as temporary blindness or aggression. Sometimes dogs will seem anxious or odd-acting just before a seizure, possibly because they are experiencing an aura as some people do.
Fly-snapping behavior, in which the dog repeatedly snaps at invisible flies, may be a type of focal seizure. Yael Merbl, DVM, DECVN, a veterinary neurologist at the Cornell University College of Veterinary Medicine, explains, “Fly biting syndrome or fly catching syndrome is a clinical phenomenon that has been shown in dogs to be caused by one of three etiologies: It can be due to gastrointestinal (GI) disease, obsessive compulsive behavior, or true epileptic seizures. Reaching a diagnosis and the most appropriate treatment plan for a specific patient may include an EEG, GI studies and dietary change, and in some cases SSRI treatment.” SSRI treatment refers to a family of anti-depressive drugs called serotonin reuptake inhibitors.
A video of the dog before, during and after a seizure can be very informative. Dogs having an epileptic seizure generally stop what they are doing and cannot be distracted. This generally doesn’t occur with other movement disorders. During a generalized seizure, the epileptic dog will often seem oblivious to their surroundings, and may have other signs such as twitching, blinking, chomping of the mouth, urination or defecation. Again, these are not typical of other movement disorders. Epileptic seizures usually last less than 5 minutes and are followed by a postictal phase, in which the dog is disoriented, groggy, restless, uncoordinated, thirsty, or hungry—sometimes even blind or aggressive. This period generally doesn’t occur with non-epileptic seizures.
Additional tests may be run to rule out possible causes. These include blood and urine tests, X-rays, and even more advanced tests, such as computed tomography, magnetic resonance imaging, bile acid tests, or cerebrospinal fluid tests may be performed. But because some of these tests can be expensive, and only a small percentage reveal any cause. Since that cause is often untreatable, most dogs are simply diagnosed with simply “idiopathic epilepsy,” meaning epilepsy of unknown origin.
The criteria for idiopathic epilepsy are
- History of two or more unprovoked epileptic seizures occurring at least 24 hours apart
- Age of first epileptic seizure between 6 months and 6 years
- No other significant neurological problems
- No related abnormalities from blood and urine tests
What Is the Treatment for Epilepsy in Dogs?
Just because your dog has one seizure doesn’t mean they’ll have another, or that they need to start on anti-seizure medication. If seizures are mild or infrequent, your dog may have a better quality of life without medication. Every case is different. But as a general rule, the International Veterinary Epilepsy Task Force (IVETF) recommends that a dog with any of the following criteria should begin anti-seizure medications:
- Two or more seizures within 6 months
- Prolonged seizures or cluster seizures
- Severe postictal signs
- Seizure severity or frequency is increasing
The initial drug of choice is generally phenobarbital. It can cause drowsiness or liver toxicity, and can interact with other certain other, so some dogs may be better candidates for another drug. Other drugs include potassium bromide, imepitoin, zonisamide, and levetiracetam (Keppra®). Gabapentin or clonazepam may be added in with any of them to achieve better results.
Surprisingly few studies exist in dogs comparing the efficacy of these drugs. The only study to compare phenobarbital to potassium bromide when given as a stand-alone drug found that phenobarbital was more effective, with 85% of dogs receiving it remaining seizure-free for 6 months, compared to 52% of dogs given potassium bromide. More often, potassium bromide is given in addition to phenobarbital. In contrast, levetiracetam has a far lower success rate as an only drug, but is helpful as an add-on with other drugs.
The IVETF provides a full comparison of ant-epileptic drugs in their report, and the American College of Internal Veterinary Medicine provides guidelines for using the various drugs.
Once you start giving anti-seizure medications, it’s very important to continue to do so on schedule, without forgetting a dose. Giving the medication erratically can increase the dog’s seizure frequency and severity. In addition, quitting the medication suddenly can bring on seizures.
Do Non-Drug Treatments Work for Epilepsy in Dogs?
Anti-seizure drugs can have side effects, so it’s natural to look for alternative therapies.
Cannabidiol (CBD) has had notable success in treating certain types of epilepsy in human children, and at least one study has reported encouraging results in dogs.
Vagal nerve stimulation, in which a pacemaker-like device electrically stimulates the left cervical vagal nerve, is approved for people and has been tried on a limited basis in dogs. It was found to effectively reduce experimentally-induced seizures in dogs, but was less successful in reducing naturally occurring ones. Nonetheless, there was some reduction in seizure activity as the trial period went on.
Acupuncture has not been shown to help, and homeopathic remedies also haven’t been shown to be helpful.
Diets with high fat, low protein, and low carbohydrates have been shown to help children with epilepsy, but have not been found to help dogs. A medium chain triglyceride (MCT) diet did result in significantly fewer seizures, however, and is the basis for one commercially available diet. “Supplementing a diet with MCT oil has been demonstrated to have similar effects,” says Munana.
Diet and Epilepsy in Dogs
But there’s another potentially important area of nutrition that’s just beginning to get attention. “Dietary effects on seizure activity are likely mediated by the microbiota-gut-brain axis, the complex connection between the gastrointestinal tract and the bacteria residing in it and the nervous system,” Munana explains. “The microbiota-gut-brain axis is an area of extensive research, and is believed to play a role in the development and progression of several neurological disorders of humans, including epilepsy. We know that the diet can alter the gut bacteria, which in turn can influence the brain and its activity. There was a recent study in mice that nicely demonstrated that the effect of the ketogenic diet is mediated by a change in the gut microbiota and associated changes in neurotransmitter concentrations (the chemicals that provide for signal transmission in the nervous system).”
What Is the Prognosis for Dogs With Epilepsy?
Over 80% of dogs respond well to anti-seizure medications. They will need periodic blood tests to monitor for liver toxicity. They may also have occasional seizures or in some cases, worsening ones that require the medication to be adjusted. Dogs with controlled seizures typically have the same life-expectancy as other dogs.
However, some dogs cease to respond, or never achieve a satisfactory response. “It’s been estimated that up to 30% of dogs will develop refractory epilepsy, meaning lack of satisfactory seizure control or side effect that impact quality of life, despite appropriate therapy with conventional antiepileptic drugs,” says Merbl.
Quality of life for both the dog and owner is a huge consideration when treating epilepsy. Most medications must be given every 12 hours. Some dogs take multiple medications, on multiple schedules. In severe cases, owners may find themselves having to wake up during the night to stay on schedule. Some people, even the most loving owners, report that they can feel trapped by their dog’s medication schedule, which sometimes mean they can’t travel, get a full night’s sleep, or travel. In addition, some dogs must take so many drugs to stave off seizures that they appear lethargic or even dazed. Everybody’s situation is different, but there may come a time when the family’s or dog’s quality of life is so negatively impacted that euthanasia may be the kindest choice.
Is There Hope for a Better Future?
Since 1995, the AKC Canine Health Foundation has invested $3M in their Epilepsy Research Initiative, continuing to fund studies dealing with diagnosis, treatment, and genetic causes.
For example, Merbl is researching a CHF-funded study examining the gut’s microbiome’s role in epilepsy. “There is a body of evidence accumulating regarding the gut microbiome impact on the central nervous system. This relates to diseases ranging from epilepsy to neurodegenerative diseases such as Alzheimer’s disease,” she explains. “One study that has led me to pursue this research discussed altering of the tight junctions (cells connections in the blood brain barrier) when the gut microbiome was changed. I was interested in testing what will happen if we change the content of the gut microbiome; can we potentially make the dogs respond better to the anti-seizure medications?”
Munana is also trying to find better ways to predict seizures. “One of the largest hardships voiced by caregivers of dogs with epilepsy is the unpredictability of seizures, and the emotional burden associated with caring for a dog with epilepsy,” she explains. Her lab is also studying the use of oral treatment protocols that owners could give their dogs undergoing cluster seizures at home, rather than having to rush them to the veterinarian—an often prohibitively expensive ordeal.
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