Why genetics matters in epilepsy

Idiopathic epilepsy — the most common form of epilepsy in dogs — is strongly influenced by genetics. This means certain breeds carry inherited variants that increase the likelihood of developing epilepsy. Understanding which breeds are predisposed helps explain why epilepsy runs in family lines, informs breeding decisions, and shapes how veterinary neurologists approach diagnosis and prognosis in different breeds.

High-prevalence breeds

Published epidemiological and genetic research has identified a number of breeds with notably elevated epilepsy prevalence compared to the general dog population:

The genetics behind idiopathic epilepsy

Epilepsy genetics in dogs is complex. In most breeds, inheritance is not straightforward — it is not a simple dominant or recessive single-gene condition. Instead, multiple genes likely interact (polygenic inheritance) to produce susceptibility. The environment then plays a role in whether that susceptibility manifests as clinical epilepsy.

In a small number of breeds, specific genetic mutations have been identified. The most well-characterized include:

• Lagotto Romagnolo — LGI2 gene mutation; causes benign juvenile epilepsy that typically resolves
• Border Collie — ADAM23 gene variant associated with idiopathic epilepsy
• Belgian Shepherd — EPMR-related genetic region identified
• Irish Wolfhound — Specific chromosomal regions associated with epilepsy susceptibility

For most other breeds, specific mutations have not been isolated despite the clinical observation of familial clustering.

What breed predisposition means for diagnosis

A dog's breed is one of the most important pieces of information in the diagnostic workup for epilepsy. According to the IVETF consensus guidelines, a dog between 6 months and 6 years of age, of a breed with known predisposition, with a normal physical and neurological examination and normal basic bloodwork, has a high probability of idiopathic epilepsy. This may reduce the necessity for advanced imaging (MRI) in straightforward cases.

Conversely, a dog outside the typical age range — particularly over 6 years — with seizures should prompt more thorough investigation for structural causes regardless of breed, as the likelihood of a brain tumor or other acquired disease increases with age.

Breed-specific considerations for long-term management

Some breeds have specific characteristics that affect how epilepsy is managed:

• Brachycephalic breeds (Bulldogs, Pugs, French Bulldogs) — Anesthesia for MRI carries additional risk due to airway anatomy; discuss this with your neurologist
• Large and giant breeds — Medication dosing is weight-based; larger dogs require larger doses of phenobarbital and may need more frequent monitoring due to body mass effects on drug distribution
• Lagotto Romagnolo with juvenile epilepsy — This specific condition often resolves by 4 months of age; prognosis is generally excellent and long-term medication may not be required

Genetic testing — what is currently available

Commercial genetic tests for epilepsy in dogs are available for a limited number of breeds — particularly where specific mutations have been identified (Lagotto Romagnolo, Border Collie). For most breeds, genetic testing is not yet clinically useful for predicting individual seizure risk. Genetic testing is more commonly used in breeding decisions — to reduce the frequency of known epilepsy-associated variants in breeding populations — than for individual pet diagnosis or management.