Seizures in dogs are triggered by a wide range of factors, from genetic predisposition and metabolic problems to everyday environmental stressors like hot weather and changes in routine. In a study of dogs with epilepsy, 74% of owners identified at least one specific factor that seemed to precipitate their dog’s seizures. Understanding these triggers can help you reduce their frequency and recognize when something more serious is going on.
How a Seizure Happens in the Brain
A seizure occurs when neurons in the brain fire in an uncontrolled, excessive burst of electrical activity. Normally, the brain maintains a balance between signals that excite neurons and signals that calm them down. The main calming chemical in the brain works to keep electrical activity in check, while the main excitatory chemical drives neurons to fire. When that balance tips too far toward excitation, or when the calming system can’t keep up, neurons start firing all at once in a chain reaction. That’s a seizure.
In younger dogs, the calming system is still developing. The connections that quiet neural activity are smaller, fewer in number, and less well-equipped with the chemical receptors needed to do their job. Meanwhile, the excitatory system is already fully built out, with an overabundance of receptors that make the young brain more susceptible to seizures. This is one reason puppies and young dogs are more vulnerable.
Stress, Weather, and Routine Changes
Environmental triggers are the most commonly reported seizure precipitants. In a study published in the Journal of Veterinary Internal Medicine, the top triggers owners identified were having visitors at home (30% of dogs), a change in life situation (27%), a change in daily routine (24%), altered sleep patterns (24%), unfamiliar places (24%), and weather changes (24%). Stress and excitement were each reported by 21% of owners when asked in open-ended questions.
Hot weather stood out as the most common weather-related trigger, affecting 22% of dogs whose owners identified precipitating factors. Cold weather was rarely involved. The timing between trigger and seizure varied: in about 35% of cases the seizure occurred within 24 hours of exposure, while 19% of dogs seized during or immediately after the triggering event. Some dogs didn’t have an immediate seizure but experienced more frequent episodes overall during stressful periods.
Hormonal factors also played a role. Among intact female dogs, 42% of owners reported that the heat cycle acted as a trigger. A third of intact male dogs had seizures linked to being around a female in heat.
Toxic Foods and Household Substances
Several common human foods can directly cause seizures in dogs. Chocolate, coffee, and anything containing caffeine belong to a chemical family that can cause tremors, seizures, and even death in pets. The darker the chocolate, the more dangerous it is. Xylitol, a sugar substitute found in sugar-free gum, candy, and some peanut butters, causes a rapid blood sugar crash that can progress to seizures. Excessively salty foods can lead to salt toxicity, which also produces tremors and seizures.
These aren’t just theoretical risks. Xylitol in particular is worth knowing about because it shows up in products you might not expect, and even small amounts can cause dangerous drops in blood sugar.
Metabolic and Organ-Related Causes
When a dog’s internal chemistry goes wrong, seizures can follow. Low blood sugar (hypoglycemia) is one of the more common metabolic triggers. Normal blood glucose in dogs falls between roughly 3.3 and 7.3 mmol/L. In one documented case involving a liver tumor, a dog’s glucose dropped to 1.5 mmol/L, triggering severe seizures.
Several conditions can cause blood sugar to plummet. Insulin-producing pancreatic tumors are a well-known culprit. Other causes include accidental xylitol ingestion, insulin overdose in diabetic dogs, extreme exertion (sometimes called “hunting dog hypoglycemia”), severe liver disease, kidney failure, and certain abdominal cancers that either consume glucose or produce insulin-like substances. Sepsis and inflammation of the pancreas can also drop blood sugar to dangerous levels.
Liver disease deserves special mention because the liver is responsible for filtering toxins from the blood. When it can’t do its job, toxic byproducts build up and can trigger seizures on their own, independent of blood sugar.
Flea and Tick Medications
The FDA has issued a specific alert about a class of flea and tick drugs called isoxazolines, which have been linked to neurologic side effects including muscle tremors, loss of coordination, and seizures. This class includes several widely prescribed products: Bravecto, Credelio, NexGard, NexGard Plus, Simparica, and Simparica Trio for dogs. The FDA notes that seizures have occurred even in dogs with no prior history of neurologic problems.
Most dogs tolerate these medications without issues, but the risk exists. If your dog has epilepsy or a history of seizures, this is worth discussing before starting or continuing one of these products.
Breeds With Higher Seizure Risk
Idiopathic epilepsy, meaning epilepsy with no identifiable underlying cause, has a genetic component in many breeds. A hereditary basis has been suggested in Beagles, Labrador Retrievers, Golden Retrievers, German Shepherds, Bernese Mountain Dogs, Belgian Tervurens, Boxers, Shetland Sheepdogs, Vizslas, English Springer Spaniels, Irish Wolfhounds, Keeshonds, and Standard Poodles. Miniature Wirehaired Dachshunds carry a specific inherited condition called Lafora disease that causes progressive seizures.
The typical window for a first seizure in idiopathic epilepsy is between 1 and 5 years of age. A seizure that first appears in this age range, with no other abnormalities on physical exam or blood work, is statistically most likely to be idiopathic epilepsy rather than a structural brain problem or metabolic disease.
What Different Seizures Look Like
Not all seizures involve dramatic convulsions. Generalized seizures (the “grand mal” type) are the most recognizable: the dog suddenly falls over with violent jerking of all four limbs, may paddle their legs, froth at the mouth, lose bladder or bowel control, and become unconscious. Other generalized types include tonic seizures (stiff, extended limbs without jerking), clonic seizures (flexed limbs without jerking), myoclonic seizures (jerking limbs), and atonic seizures where the dog simply stands, stares, and becomes unresponsive.
Focal seizures look very different because the abnormal electrical activity is confined to one area of the brain. A dog might repeatedly snap at invisible flies (“fly-biting”), clack their jaw rhythmically (“chewing gum fit”), or show nothing more than a twitching eyelid, lip, or ear. Consciousness isn’t necessarily lost during a focal seizure, which makes them easy to miss or mistake for a quirky behavior.
Warning Signs Before and After a Seizure
Many dogs show behavioral changes in the minutes before a seizure. This pre-seizure phase can include hyperexcitement, disorientation, increased sensitivity to touch or sound, and facial itching. It typically lasts around 60 seconds, though some owners report subtler changes in mood or clinginess in the hours beforehand. Recognizing these signs can give you a brief window to move your dog to a safe space away from stairs, furniture edges, or water.
After a seizure ends, the recovery period (called the postictal phase) brings its own set of symptoms. Disorientation and repetitive pacing are the most common, followed by loss of coordination and temporary blindness. About half of owners report these signs lasting between 1 and 30 minutes. Another 20% say recovery takes 30 to 60 minutes. During this time, your dog may seem confused, bump into things, or not recognize you briefly. This is normal post-seizure behavior and resolves on its own.
How Epilepsy Is Diagnosed
There’s no single test that confirms epilepsy. Instead, veterinarians work through a process of elimination. The International Veterinary Epilepsy Task Force defines three levels of diagnostic confidence. At the most basic level, a dog qualifies for a presumptive diagnosis if they’ve had two or more unprovoked seizures at least 24 hours apart, were between 6 months and 6 years old at first seizure, have a normal neurological exam between episodes, and show no significant abnormalities on blood work and urinalysis.
Higher confidence comes from additional testing. The second tier adds brain imaging (MRI) and spinal fluid analysis, both of which should come back normal in true idiopathic epilepsy. The third and highest tier adds electrical brain recordings that show seizure-like patterns matching criteria used in human neurology. Most pet dogs are diagnosed at the first or second tier, since brain wave monitoring requires specialized equipment and is less commonly available in veterinary practice.