Epilepsy is more common in purebred dogs than mixed breeds, and certain breeds carry a significantly higher genetic risk. Breeds with well-documented susceptibility include Belgian Tervuren, Border Collies, Beagles, Labrador Retrievers, Golden Retrievers, Boxers, Bernese Mountain Dogs, Cocker Spaniels, Standard Poodles, and Lagotto Romagnolos. The Belgian Tervuren has one of the highest known prevalence rates of any breed, with estimates reaching 27% of the population.
Breeds With the Highest Risk
Not all at-risk breeds face the same odds. The Belgian Tervuren stands out: a survey by the American Belgian Tervuren Club in the 1980s estimated epilepsy prevalence at 17%, and more recent data from a cohort of 144 dogs born between 2000 and 2020 put the figure at just over 27%. That means roughly one in four Belgian Tervuren in that study had experienced multiple seizures. The closely related Belgian Sheepdog shares this vulnerability, with a combined prevalence estimate of 9.5% for both breeds together.
Border Collies face not just a higher risk of epilepsy but a particularly severe form of it. Research into epilepsy in the breed found that 71% of Border Collies treated with at least two anti-seizure medications were drug-resistant, meaning the standard medications failed to adequately control their seizures. This is a notably higher resistance rate than what’s seen across dogs in general.
Other breeds consistently identified as predisposed include Beagles, Bernese Mountain Dogs, Boxers, Cocker Spaniels, Labrador Retrievers, Golden Retrievers, English Springer Spaniels, and Vizslas. Each of these breeds has enough documented cases that veterinary geneticists consider epilepsy a breed-associated condition rather than a random occurrence.
When Seizures Typically Start
Most dogs with inherited epilepsy have their first seizure between 1 and 5 years of age. This is the classic window for what veterinarians call idiopathic epilepsy, meaning epilepsy with no identifiable structural cause in the brain. A seizure in a 2-year-old Labrador, for example, is far more likely to be genetic epilepsy than a seizure in a 9-year-old Labrador, which raises more concern about tumors or other underlying disease.
There are exceptions to this window. Standard Poodles tend to develop seizures a bit later, with a median onset around 3.7 years, and some don’t have their first seizure until after age 5. On the other end of the spectrum, Lagotto Romagnolo puppies can begin seizing as young as 5 weeks old. Their form of epilepsy, called benign familial juvenile epilepsy, causes focal seizures involving whole-body trembling, loss of coordination, and stiffness. The good news for Lagotto owners is that these seizures typically resolve on their own by 13 weeks of age.
How Genetics Drive Seizure Risk
Epilepsy in dogs runs in families, and in some breeds researchers have pinpointed the exact genetic mechanism. In Lagotto Romagnolos, a specific mutation in the LGI2 gene causes their juvenile seizure disorder. Dogs that carry even one copy of this mutation can develop seizures similar to those seen in dogs with two copies. Genetic testing for this mutation is now available, giving breeders a tool to reduce its prevalence.
In Standard Poodles, epilepsy appears to follow a simple recessive inheritance pattern with nearly complete penetrance. That means a dog needs to inherit the faulty gene from both parents to develop seizures, but if it does inherit both copies, it will almost certainly be affected. About 93% of Standard Poodles with inherited epilepsy in one study experienced focal seizures (originating in one area of the brain) that sometimes spread to become full-body convulsions.
For most other breeds, the genetics are more complicated. Epilepsy in Belgian Tervuren, Border Collies, and many other breeds likely involves multiple genes rather than a single mutation, which makes it harder to develop a simple screening test. The rise in prevalence among Belgian Tervuren from 17% to 27% over roughly four decades suggests that breeding practices have not yet brought the condition under control in that population.
What Seizures Look Like in Dogs
Seizures in dogs fall into two broad categories. Generalized seizures involve the whole body: your dog may fall to one side, paddle their legs, clench their jaw, drool, and lose bladder or bowel control. These episodes typically last 30 seconds to 2 minutes. Focal seizures affect only one part of the body or one side of the face, sometimes showing up as twitching, repetitive movements, or brief episodes of staring and unresponsiveness. Focal seizures can progress into generalized ones.
Between seizures, most dogs with idiopathic epilepsy appear completely normal on a physical and neurological exam. This is actually one of the diagnostic criteria: if your dog seems neurologically off between episodes, that points toward a structural brain problem rather than inherited epilepsy.
How Epilepsy Is Diagnosed
There’s no single test that confirms idiopathic epilepsy. Instead, vets work through levels of diagnostic confidence by ruling out other causes. The baseline criteria include a history of two or more unprovoked seizures at least 24 hours apart, onset between 6 months and 6 years of age, a normal neurological exam between episodes, and normal bloodwork.
If your vet wants more certainty, the next step involves fasting bile acid tests (to rule out liver problems that can cause seizures), a brain MRI, and spinal fluid analysis. When all of those come back normal in a dog that fits the age and breed profile, the diagnosis of idiopathic epilepsy becomes quite confident. The highest level of certainty involves detecting abnormal electrical activity in the brain, though this type of testing is mainly available at veterinary specialty hospitals.
Treatment Expectations
Anti-seizure medication is the standard treatment, but the results are sobering. Only about 30 to 40% of dogs with epilepsy achieve complete seizure freedom on medication. Another 30 to 40% are considered non-responders, meaning their seizure frequency doesn’t decrease by even half. The remaining dogs fall somewhere in between, with partial improvement.
These averages mask significant breed differences. Border Collies, as noted, have an especially high rate of drug resistance. If you have a breed with known treatment challenges, your vet may recommend trying combinations of medications or exploring additional options sooner rather than later.
One supplemental approach that has shown modest promise is adding medium-chain triglyceride (MCT) oil to the diet. In a clinical study of dogs with idiopathic epilepsy, over 60% experienced some reduction in seizure frequency when given MCT oil, though only 30% achieved a meaningful reduction of 50% or more. Some dogs actually had an increase in seizures. MCT oil is not a replacement for medication, but for dogs that respond to it, the combination may provide better control than medication alone.
What Breed Risk Means in Practice
Being a high-risk breed doesn’t mean your dog will develop epilepsy. Even in Belgian Tervuren, the breed with the highest documented prevalence, roughly three out of four dogs never seize. But if you own or are considering one of these breeds, it’s worth knowing the signs and the typical age of onset so you’re not caught off guard.
If you’re choosing a puppy from a high-risk breed, ask the breeder about seizure history in the parents and their lines. For breeds where genetic tests exist, like the Lagotto Romagnolo, responsible breeders should be screening. For breeds where no test is available yet, a breeder who tracks health outcomes across generations and avoids pairing two dogs with family histories of seizures is doing the best they can with current tools.