Seizures in dogs

Overview

Epileptic seizures and other convulsions

During an epileptic seizure, brain neurons briefly activate excessively and simultaneously. Movement, consciousness or behaviour may change. Whole-body convulsions are one manifestation.

A single episode can be a reaction to temporary poisoning or metabolic disturbance. Epilepsy involves a tendency to have at least two unprovoked seizures at least 24 hours apart.

UK primary care records noted at least one seizure in 0.82% of dogs during 2013. A first seizure was recorded in 0.62% that year.

A prolonged seizure is termed status epilepticus when convulsions continue at five minutes. This also includes repeated seizures without regaining consciousness between them.

Movement signs of a brief seizure usually stop spontaneously, but recovery can take time. Cluster seizures may individually stop spontaneously but recur several times within a day.

Causes

Causes outside the brain

Low blood glucose can trigger a seizure. Electrolyte disturbances can also do so. Liver dysfunction can cause reactive seizures. Poisoning can abruptly alter brain function without epilepsy.

Brain disease and seizure susceptibility

A tumour can trigger seizures by altering surrounding tissue function. Brain inflammation or vascular disease can also cause them. Head trauma can damage brain tissue and predispose to seizures. If investigations find no other cause and episodes recur, idiopathic epilepsy may be diagnosed.

In a group treated for status epilepticus, 28 dogs had inflammatory brain disease. Poisoning was suspected in 16.

Xylitol-containing products are one possible exposure investigated after sudden seizures. Kidney disease-related metabolic disturbances can predispose to reactive seizures. Severe overheating can itself trigger an episode.

Risk factors

Idiopathic epilepsy is often suspected with onset between six months and six years. Inherited epilepsy can involve several genes alongside environmental factors. Onset clearly outside the usual age range particularly prompts investigation of other causes. UK records found a seizure odds ratio of 3.41 in Pugs compared with Labrador Retrievers. Median age of all dogs with seizures in the UK population was 7.27 years.

Inherited epilepsy often first causes seizures at one to five years. Structural epilepsy often starts later than idiopathic disease. Entire males had an odds ratio of 1.47 compared with entire females in the UK population.

Poisoning is especially important to investigate after access to slug bait or antifreeze. Status epilepticus was the first observed seizure in 56 dogs in one hospital follow-up.

Typical symptoms

Generalised seizures can cause unconsciousness.

• Stiffening before rhythmic limb movement.
• Running or paddling leg movements.
• Profuse drooling.
• Urination during the episode.
• Repeated eyelid, lip or ear twitching in focal-onset seizures.
• Sometimes rhythmic jaw movements resembling chewing.

Consciousness can remain during focal-onset seizures. These can spread into generalised seizures. Individual convulsive episodes often last one to two minutes. Afterwards, dogs may be restless, confused or temporarily blind.

Behaviour can change before convulsions start. During recovery, dogs may wander restlessly or sleep deeply. Hunger or thirst can increase afterwards.

Some focal-onset seizures affect only a limb on one side. Generalised seizures can start during rest or sleep. Post-seizure confusion can last minutes to hours.

Complications and consequences

Prolonged seizure effects

Long convulsions can dangerously raise temperature. Continuous muscle activity can break down muscle cells. Released myoglobin can damage kidney tubules. Prolonged seizures can cause oxygen deprivation. Around 30 minutes of continuing seizure activity can permanently damage brain cells.

Rarely, fluid accumulates in the lungs after severe or continuous seizures. Muscle injury can turn urine reddish through myoglobin.

Recovery after status epilepticus

Among 124 dogs at three hospitals, 29.8% died or were euthanased during admission for status epilepticus. Recurrence information was available for 74 of 87 discharged dogs. Status epilepticus recurred in 20, or 27%, of those followed. Median recurrence follow-up was nine months. Half of recurrences occurred within two months of discharge. Previously drug-resistant epilepsy was associated with greater recurrence likelihood.

Diagnosis at the vet

Identifying the episode

Details of onset, duration and recovery help identify an epileptic seizure. Video can show whether twitching started in one limb or one side of the face. Fainting can resemble seizures because muscle jerks can occur. Recovery after fainting is usually rapid, whereas confusion can follow seizures. Collapse during exertion or coughing also prompts investigation of cardiac fainting.

Falls can also reflect vestibular disease with head tilt and involuntary eye movements. Episodic movement disorders can cause involuntary contractions resembling focal seizures. If fainting is suspected, the vet may look for arrhythmia, a murmur or abnormal pulses.

Blood tests and brain investigations

Emergency glucose testing can identify low values needing immediate correction. Blood tests also assess electrolytes and liver function. Neurological examination helps localise possible injury. MRI can investigate suspected structural causes. Cerebrospinal fluid examination can investigate conditions such as inflammatory brain disease. EEG can detect abnormal electrical activity associated with seizures.

Video EEG is used in specialist canine epilepsy investigations.

Urinalysis can form part of basic investigations for metabolic causes. EEG is not universally available, so assessment often relies on owner accounts and video.

Treatment

Treating a prolonged seizure

Emergency care starts with stabilising vital functions and stopping ongoing seizure activity. A rapidly acting anticonvulsant such as a benzodiazepine aims to stop status epilepticus. Persistent seizures despite anticonvulsants may need anaesthesia. Temperature and oxygenation are monitored because prolonged seizures can disrupt both. Low-glucose seizures also require correction of the trigger.

Levetiracetam can provide additional hospital treatment alongside the rapid first-line medicine. Electrolyte disturbances can be corrected while anticonvulsants act. Median hospital stay for status epilepticus in the UK 124-dog follow-up was three days.

Follow-up and long-term medication

Long-term anticonvulsants aim to reduce frequency and severity. Need is assessed individually: not every brief isolated seizure requires ongoing medication. UK primary care records showed no anticonvulsant started at the first recorded seizure for 1,960 of 2,834 dogs, or 69.2%. Some dogs may be prescribed home rescue medication.

Epilepsy reviews examine seizure diaries and treatment effectiveness. They also assess adverse effects.

Long-term planning balances seizure control against medication side effects.

Prevention

Keep human medicines inaccessible because some can cause seizures if swallowed. Treating an underlying metabolic disturbance, for example, can prevent further reactive seizures. For epilepsy, try to avoid known individual triggers.

Abrupt changes to prescribed ongoing anticonvulsants can trigger seizures. Consistent use as prescribed helps maintain control.

Keep xylitol-containing gum and sweets in a closed cupboard because ingestion can cause seizures.

Important for dog owners

Time when the episode starts and convulsions stop. Move nearby objects that could cause injury. Prevent falls down stairs if safe to do so. Film only after ensuring canine and human safety. Allow quiet rest afterwards. Offer water only once swallowing is normal. Record behaviour before the seizure and recovery speed too.

Keep children and other pets away during seizures. Call an emergency service if your usual practice is closed and immediate care is needed.

Tell the vet current medicines and when they were last given.

Check substances that can poison dogs.

Frequently asked questions

What should I do for a first seizure?

Make the surroundings safe and time it. Contact a vet immediately even with rapid recovery. Blood tests and neurological examination may be needed to identify poisoning or liver disease, for example.

How can I distinguish a seizure from fainting?

Fainting can also cause muscle jerks, so twitching alone does not identify the cause. Dogs usually recover quickly after fainting. Safely filmed video can help, and heart function may also be investigated.

Can a dog swallow its tongue during a seizure?

No. Do not put hands in the mouth because jaw convulsions can cause involuntary biting. Remove nearby objects to protect against injury.

Can a seizure stop on its own?

An individual episode can stop spontaneously within one to two minutes. Seek emergency care immediately if convulsions reach five minutes. Emergency care is also needed if another starts before consciousness returns.

Does one seizure mean epilepsy?

A single seizure can result from temporary metabolic disturbance or poisoning. Epilepsy involves recurrent seizures without such an immediate trigger. Investigations look for other treatable causes.