Why is my old dog having seizures? 9 causes and what to do

Few things are more terrifying than watching your senior dog have a seizure. One moment they're lying peacefully on their bed, and the next they're on their side, body rigid, legs paddling, jaw clenching, eyes rolling. You feel helpless. You feel panicked. And when it's over, you're left shaking almost as much as they are, wondering what just happened and whether your old friend is going to be okay.

If your senior dog has started having seizures, especially if they've never had one before, something has changed in their body that needs investigation. Unlike younger dogs who may develop idiopathic epilepsy (seizures with no identifiable cause), new-onset seizures in dogs over the age of 7 almost always have an underlying medical cause. Finding that cause is critical.

This guide will help you understand why your old dog is having seizures, what to do when one happens, when it's an emergency, and how your vet can help.

What happens during a seizure

A seizure is caused by abnormal electrical activity in the brain. Think of it as an electrical storm: neurons that normally fire in controlled, coordinated patterns suddenly begin firing chaotically and uncontrollably. This disrupted signaling can affect the entire body.

Seizures in dogs typically progress through three phases:

• Pre-ictal phase (aura): In the minutes or hours before a seizure, your dog may act strangely. They may become clingy, restless, anxious, whine, pace, hide, stare into space, or seem disoriented. Some owners learn to recognize these signs and know a seizure is coming.
• Ictal phase (the seizure itself): This is the seizure event. It may be a full-body convulsion (generalized seizure) or a more subtle event affecting only part of the body (focal seizure). Generalized seizures involve collapse, rigid limbs, paddling motions, jaw clenching or chomping, drooling, and sometimes loss of bladder or bowel control. Focal seizures may involve twitching of one limb, one side of the face, or repetitive movements like head bobbing or fly-biting (snapping at the air). Most seizures last 30 seconds to 2 minutes.
• Post-ictal phase (recovery): After the seizure, your dog will be disoriented and confused. They may pace, bump into things, seem temporarily blind, be ravenously hungry or thirsty, or just seem "out of it." This phase can last from a few minutes to several hours. Some dogs recover quickly, while others remain dazed and wobbly for the rest of the day.

Why new-onset seizures in senior dogs are different

This is an important distinction that many pet owners don't realize. In younger dogs (typically under 5-6 years old), the most common diagnosis for recurring seizures is idiopathic epilepsy, a genetic condition where the brain is simply more prone to seizure activity. There's no tumor, no toxin, no organ failure, the brain just misfires sometimes.

In senior dogs, idiopathic epilepsy is not a typical new diagnosis. If your dog is 7 or older and having seizures for the first time, your veterinarian will look for a specific, identifiable cause. The seizure is a symptom of something else going on, and finding that something is essential for proper treatment.

This doesn't mean the news is always bad. Some causes of seizures in older dogs are very treatable. But it does mean that a "wait and see" approach is not appropriate. New-onset seizures in a senior dog warrant a thorough veterinary workup.

9 common causes of seizures in senior dogs

1. Brain tumors

This is the most common cause of new-onset seizures in dogs over 5 years of age. Brain tumors can be primary (originating in the brain) or secondary (cancer that has spread from elsewhere in the body). The most common primary brain tumors in dogs are meningiomas and gliomas.

Brain tumors cause seizures by putting pressure on surrounding brain tissue, disrupting normal electrical activity, or by directly invading brain structures involved in seizure regulation. Breeds with higher risk include Boxers, Golden Retrievers, Boston Terriers, French Bulldogs, and other brachycephalic (flat-faced) breeds.

Signs that a brain tumor may be causing your dog's seizures:

• Seizures that become progressively more frequent or severe over weeks to months
• Behavioral or personality changes (confusion, aggression, loss of house training)
• Circling, head pressing, or walking into walls
• Vision changes or blindness, especially on one side
• Head tilt or coordination problems
• Progressive neurological decline between seizure episodes

Diagnosis requires advanced imaging, typically an MRI. While a brain tumor diagnosis is serious, treatment options exist including surgery (especially for meningiomas, which are often accessible and slow-growing), radiation therapy, and palliative care with anti-seizure medication and steroids to reduce brain swelling. Many dogs live months to years with proper management.

2. Liver disease (hepatic encephalopathy)

The liver plays a crucial role in filtering toxins from the blood. When the liver fails, toxins, particularly ammonia, accumulate in the bloodstream and reach the brain, causing a condition called hepatic encephalopathy. This toxic buildup can trigger seizures.

Liver disease becomes more common with age and can develop from chronic hepatitis, cirrhosis, liver tumors, toxin exposure, or portosystemic shunts (abnormal blood vessels that bypass the liver).

Signs of liver-related seizures:

• Seizures that may be associated with meals (especially high-protein meals)
• Episodes of disorientation, aimless wandering, or head pressing between seizures
• Jaundice (yellowing of the eyes, gums, or skin)
• Decreased appetite and weight loss
• Increased thirst and urination
• Vomiting or diarrhea
• Swollen abdomen from fluid accumulation

Blood work can reveal elevated liver enzymes, bile acids, and ammonia levels. Treatment focuses on managing the underlying liver disease, reducing ammonia production through dietary changes and medications like lactulose, and controlling seizures with brain-safe anti-seizure drugs.

3. Kidney disease (uremic encephalopathy)

Similar to liver disease, advanced kidney disease allows waste products to build up in the blood. When these uremic toxins reach high levels, they can affect the brain and trigger seizures. This is called uremic encephalopathy and typically occurs in the later stages of chronic kidney disease.

If your senior dog has been diagnosed with kidney disease and starts having seizures, it usually indicates the disease has progressed significantly. Other signs include:

• Significantly increased thirst and urination
• Loss of appetite and weight loss
• Vomiting and nausea
• Bad breath with a chemical or ammonia-like smell
• Lethargy and weakness
• Muscle twitching (which may precede full seizures)
• Mouth ulcers

Treatment focuses on aggressive management of the kidney disease itself, including fluid therapy, dietary changes, and medications to control toxin levels. If the underlying uremia can be reduced, the seizures often improve.

4. Low blood sugar (hypoglycemia)

The brain depends entirely on glucose for energy. When blood sugar drops too low, the brain can't function properly, and seizures can result. In senior dogs, hypoglycemia is most commonly caused by:

• Insulin overdose: In diabetic dogs receiving insulin injections, too much insulin or a missed meal can cause dangerous blood sugar drops
• Insulinoma: A tumor of the pancreas that produces excess insulin. This is an important cause of seizures in middle-aged and older dogs, particularly larger breeds
• Liver failure: The liver stores and releases glucose. Severe liver disease can impair this function
• Sepsis: Overwhelming infection can deplete blood sugar
• Prolonged fasting: In small or debilitated senior dogs, going too long without food can cause drops in blood sugar

Hypoglycemic seizures often occur after exercise, after a long period without food, or in diabetic dogs shortly after an insulin injection. Your dog may seem weak, wobbly, or disoriented before the seizure begins. A blood glucose test at the vet can quickly identify this as the cause.

5. Toxin exposure

Certain toxins can cause seizures, and senior dogs may be more vulnerable due to slower metabolism and reduced organ function. Common seizure-inducing toxins include:

• Metaldehyde (slug and snail bait): Extremely dangerous and can cause rapid-onset seizures
• Xylitol (artificial sweetener): Found in sugar-free gum, candy, and some peanut butters. Causes severe hypoglycemia and liver failure
• Chocolate and caffeine: Theobromine toxicity can cause seizures, especially with dark chocolate
• Certain medications: Overdose of human medications like antidepressants, ADHD medications, or even some veterinary drugs
• Mycotoxins: Mold toxins found on spoiled food, compost, or garbage
• Rodenticides: Some types can cause seizures, particularly bromethalin-based products
• Organophosphate insecticides: Found in some yard and garden products

If you suspect your dog has ingested a toxin and is having seizures, this is a life-threatening emergency. Get to an emergency vet immediately and, if possible, bring the packaging of whatever your dog may have consumed. Time is critical with toxin-induced seizures.

6. Stroke (cerebrovascular accident)

Yes, dogs can have strokes. While less common than in humans, strokes become more likely as dogs age, particularly in dogs with underlying conditions like Cushing's disease, heart disease, high blood pressure, kidney disease, or hypothyroidism.

A stroke occurs when blood flow to part of the brain is interrupted, either by a blood clot (ischemic stroke) or a ruptured blood vessel (hemorrhagic stroke). Seizures can occur during or shortly after a stroke.

Signs of a stroke in dogs:

• Sudden onset of neurological symptoms (not gradual)
• Head tilt
• Loss of balance, falling to one side
• Rapid eye movements (nystagmus)
• Circling in one direction
• Sudden blindness
• Confusion or disorientation
• Collapse

The good news about strokes in dogs is that many dogs recover significantly, sometimes fully, with supportive care. The brain has remarkable ability to compensate for damaged areas. Treatment focuses on supportive care, managing the underlying condition that caused the stroke, and controlling any seizure activity.

7. Electrolyte imbalances

The brain's electrical activity depends on a precise balance of electrolytes, particularly sodium, calcium, and potassium. When these become significantly imbalanced, seizures can result. In senior dogs, electrolyte imbalances can be caused by:

• Low sodium (hyponatremia): Can result from excessive water intake, Addison's disease, or severe diarrhea and vomiting
• Low calcium (hypocalcemia): Can be caused by kidney disease, hypoparathyroidism, pancreatitis, or certain medications
• High or low potassium: Often related to kidney disease, Addison's disease, or medication effects

Electrolyte imbalances are easily detected through routine blood work and are usually correctable. If your dog's seizures are caused by an electrolyte imbalance, correcting the imbalance typically stops the seizures, though the underlying cause of the imbalance needs to be addressed as well.

8. Inflammatory brain disease (encephalitis)

Encephalitis, inflammation of the brain, can occur at any age but has specific forms that affect older dogs. Causes include:

• Immune-mediated encephalitis: The body's immune system attacks the brain tissue. Several forms exist, including granulomatous meningoencephalomyelitis (GME) and necrotizing encephalitis, which tend to affect small breeds like Pugs, Maltese, and Chihuahuas
• Infectious encephalitis: Caused by tick-borne diseases (ehrlichiosis, Rocky Mountain spotted fever), fungal infections (cryptococcosis, blastomycosis), or, rarely, viral infections like distemper in unvaccinated dogs
• Steroid-responsive meningitis-arteritis: An immune-mediated condition that can recur in older dogs

Signs of encephalitis include seizures, fever, neck pain or stiffness, behavioral changes, loss of coordination, and progressive neurological decline. Diagnosis often involves MRI and analysis of cerebrospinal fluid. Treatment depends on the cause but may include immunosuppressive drugs, antibiotics, or anti-fungal medications.

9. Idiopathic epilepsy (pre-existing)

While new-onset idiopathic epilepsy is uncommon in senior dogs, some dogs have had epilepsy their entire lives. If your senior dog has been having seizures since they were young (typically first appearing between ages 1-5), they may have idiopathic epilepsy that is now worsening with age.

Aging can change seizure patterns in epileptic dogs. Seizures may become more frequent, more severe, or harder to control with previously effective medications. This can happen because:

• The brain becomes more susceptible to seizure activity with age
• Changes in liver or kidney function affect how the body processes anti-seizure medications
• A new condition has developed alongside the existing epilepsy
• Drug tolerance has developed over years of medication use

If your epileptic dog's seizures are changing in character or frequency, your vet may need to adjust medications, add a second drug, or run new diagnostics to make sure nothing else is going on.

What to do when your dog has a seizure

Watching your dog seize is one of the most helpless feelings in the world. But what you do (and don't do) during a seizure matters.

During the seizure

• Stay calm. Your dog is not in pain during the seizure and is not conscious of what's happening. They need you to think clearly.
• Do not put your hands near their mouth. Dogs cannot swallow their tongues. You will get bitten, likely badly. Jaw muscles contract with enormous force during a seizure.
• Move dangerous objects away. Clear the area around your dog. Push away furniture, sharp objects, or anything they could hit during convulsions.
• If they're on a high surface like a couch or bed, gently ease them to the floor to prevent a fall.
• Time the seizure. Use your phone. This information is critical for your vet. It will feel like the seizure lasts forever, but most are under 2 minutes.
• If possible, take a video. A video of the seizure is worth a thousand descriptions to your veterinarian. It helps them determine the seizure type and guide their workup.
• Dim the lights and reduce noise. Bright lights and loud sounds can intensify or prolong the seizure.
• Do not restrain your dog. You cannot stop the seizure by holding your dog still. Restraint can cause injury to both of you.

After the seizure

• Speak softly and calmly. Your dog will be confused and disoriented. A gentle, reassuring voice helps.
• Keep them in a safe, quiet area. They may stumble, pace, or bump into things during recovery.
• Offer water once they seem alert enough to drink safely. Don't force it.
• Keep other pets away. Other animals may react unpredictably to a seizing or post-ictal dog, and your recovering dog doesn't need the added stress.
• Monitor them closely for the next few hours. Note how long it takes them to return to normal behavior.
• Call your vet. Even if your dog seems to recover fully, a first-time seizure in a senior dog always warrants a veterinary evaluation.

When a seizure is a medical emergency

Go to an emergency vet immediately if:

• The seizure lasts more than 5 minutes. This is called status epilepticus and is life-threatening. Prolonged seizure activity can cause brain damage, dangerously high body temperature, and organ failure.
• Your dog has multiple seizures within a 24-hour period (cluster seizures). Even if each individual seizure is short, clusters indicate the brain is in a highly unstable state and the next seizure could become prolonged.
• Your dog doesn't regain consciousness between seizures. This is another form of status epilepticus and is extremely dangerous.
• The seizure occurs after a known toxin exposure.
• Your dog has difficulty breathing during or after the seizure.
• Your dog is a known diabetic. The seizure may be caused by dangerously low blood sugar that needs immediate correction.
• This is your dog's first seizure and they are showing other neurological signs like head tilt, circling, blindness, or inability to walk.

When in doubt, err on the side of caution and seek emergency care. Seizures that seem mild can escalate quickly in senior dogs, and the underlying cause may be time-sensitive.

What to expect at the vet

When you bring your senior dog in for seizures, your veterinarian will typically perform:

• Complete physical and neurological examination: Checking reflexes, eye responses, coordination, mental alertness, and looking for any abnormalities that point to a specific cause
• Comprehensive blood work: A full chemistry panel and complete blood count to check liver function, kidney function, blood sugar, calcium, electrolytes, and look for signs of infection or inflammation
• Urinalysis: To further assess kidney function
• Blood pressure measurement: High blood pressure can contribute to seizures
• Thyroid testing: Hypothyroidism can lower the seizure threshold

Depending on initial findings, your vet may recommend:

• MRI: The gold standard for evaluating the brain. This is the only reliable way to detect brain tumors, strokes, inflammatory brain disease, and structural abnormalities. MRI requires general anesthesia, which your vet will discuss with you given your dog's age and health status.
• Cerebrospinal fluid (CSF) analysis: Often performed at the same time as an MRI to check for infection or inflammation in the brain and spinal cord
• Abdominal ultrasound: To look for tumors that may have spread to the brain or conditions like insulinoma
• Chest X-rays: To check for cancer that may have metastasized

Before your appointment, prepare notes about: when the seizure occurred, how long it lasted, what it looked like (or bring your video), any changes in behavior before or after, all current medications and supplements, any possible toxin exposure, and your dog's recent health history.

Treatment options for seizures in senior dogs

Treatment depends entirely on the underlying cause. However, there are some general principles:

Anti-seizure medications

If your dog is having recurrent seizures, your vet will likely prescribe daily anti-seizure medication. The most commonly used drugs include:

• Phenobarbital: The most widely used anti-seizure drug in dogs. Effective and affordable, but requires periodic blood level monitoring and can affect the liver over time
• Levetiracetam (Keppra): Increasingly popular because it has fewer side effects and is easier on the liver and kidneys. Often preferred in senior dogs with compromised organ function
• Potassium bromide: Sometimes used in combination with phenobarbital or as an alternative. Not ideal for dogs with kidney disease
• Zonisamide: Another option with a relatively mild side effect profile

In senior dogs, medication choice is particularly important because aging organs process drugs differently. Your vet will consider your dog's liver function, kidney function, and other medications when choosing an anti-seizure drug. Regular blood work to monitor drug levels and organ function is essential.

Treating the underlying cause

Whenever possible, addressing the root cause is more effective than just managing seizures:

• Brain tumors: Surgery, radiation, chemotherapy, or palliative care with steroids
• Liver disease: Dietary management, medications, and supplements to support liver function
• Kidney disease: Fluid therapy, dietary changes, and medications to reduce toxin buildup
• Hypoglycemia/insulinoma: Dietary management (frequent small meals), surgery to remove the tumor, or medical management
• Electrolyte imbalances: Correcting the imbalance and addressing its cause
• Encephalitis: Immunosuppressive drugs or antibiotics depending on the cause

Emergency medications for home use

If your dog has recurrent seizures, your vet may prescribe emergency medication to administer at home during a seizure. Diazepam (Valium) rectal gel or intranasal midazolam can help stop a prolonged seizure or prevent cluster seizures. Your vet will teach you exactly how and when to use these. Having them on hand provides enormous peace of mind.

Living with a senior dog who has seizures

Managing seizures in an older dog requires some adjustments to daily life, but many dogs with controlled seizures live happily and comfortably.

Keep a seizure diary

Record every seizure: date, time, duration, what it looked like, anything unusual before or after, and what your dog ate that day. This information helps your vet identify patterns and adjust treatment. Many pet owners use a simple notebook or a notes app on their phone.

Safety-proof your home

• Block access to stairs and pools
• Keep your dog off elevated surfaces like beds and couches if seizures are frequent
• Pad sharp corners on furniture at your dog's head height
• Make sure their bed is on the floor in a safe, open area

Medication consistency

Anti-seizure medications must be given at the same times every day. Missed doses or inconsistent timing can trigger breakthrough seizures. Set phone alarms, use a pill organizer, and have a backup plan for when you're away from home. Never abruptly stop anti-seizure medication, as sudden withdrawal can cause severe, life-threatening seizures.

Regular veterinary monitoring

Your dog will need regular blood work (typically every 3-6 months) to monitor drug levels and organ function. Keep all follow-up appointments even if your dog seems to be doing well. Catching problems early, whether it's a drug level that's drifting or liver values that are creeping up, allows for proactive adjustments rather than reactive crisis management.

Frequently asked questions

Can an old dog die from a seizure?

A single, brief seizure (under 2 minutes) is rarely fatal on its own. However, prolonged seizures (status epilepticus lasting more than 5 minutes) can be life-threatening due to brain damage, overheating, and organ failure. Cluster seizures also carry serious risks. The underlying cause of the seizure, such as a brain tumor or organ failure, poses its own risks to your dog's life. This is why prompt veterinary evaluation is so important.

Are seizures painful for my dog?

During a generalized seizure, your dog is unconscious and not experiencing pain from the seizure itself. They are not aware of what's happening. Afterward, they may be sore from the intense muscle contractions, confused, and exhausted, but the seizure itself is not a pain experience the way it appears to observers. That said, if the underlying cause (like a brain tumor) is causing headaches or discomfort, that pain exists independently of the seizures.

How many seizures is too many?

There's no single magic number, but generally, veterinary neurologists recommend starting anti-seizure medication if a dog has more than one seizure every 6-8 weeks, has cluster seizures (more than one in 24 hours), has a seizure lasting more than 5 minutes, or if the severity of seizures is worsening. For senior dogs with identified underlying causes, treatment may begin after even a single seizure depending on the diagnosis.

Should I consider putting my dog down because of seizures?

Seizures alone are not necessarily a reason for euthanasia if they can be managed and your dog has good quality of life between episodes. Many dogs with controlled seizures live happy, comfortable lives. However, if seizures are uncontrollable despite medication, if the underlying cause is untreatable and progressive, or if your dog's quality of life has significantly deteriorated, then having a compassionate conversation with your vet about end-of-life options is appropriate. Quality of life between seizures is the most important factor to assess.

Can diet affect seizures in older dogs?

Diet can play a role, particularly if the seizures are related to liver disease, kidney disease, hypoglycemia, or diabetes. Some research suggests that medium-chain triglyceride (MCT) supplementation may help reduce seizure frequency in dogs, and special diets enriched with MCTs are available. Always discuss dietary changes with your vet, especially if your dog is on anti-seizure medications, as some nutrients and supplements can interact with these drugs.

Watching your old dog have a seizure is one of the most frightening experiences a pet owner can face. But seizures in senior dogs, while always serious, are often manageable, and sometimes the underlying cause is treatable. The most important thing you can do is get your dog to the vet promptly, stay calm during episodes, and follow your treatment plan consistently. Your senior dog is relying on you to be their advocate, and the fact that you're reading this article means you already are.