Canine Epilepsy and the Causes of Canine Seizures

There are many causes of canine seizures, and fortunately for some dogs, those seizures are isolated incidents.

For many dogs however, the incidence of a seizure may not be isolated. When this is the case, it may be that the dog is suffering from canine epilepsy.

Note that epilepsy and seizure are not synonyms. Epilepsy is a cause of seizures and is sometimes referred to as ‘recurrent seizure disorder‘ due to the fact that epilepsy sufferers experience frequent seizures.

There are many similarities between canine epilepsy and human epilepsy, the main difference being the method of treatment, but also that it may be more difficult to recognise the occurrence of a canine seizure in some instances.

What is Canine Epilepsy?

As mentioned earlier, canine epilepsy is a recurrent seizure disorder, where the dog experiences frequent seizures. In general, a dog suffering from a seizure or more a month is considered to be epileptic. Isolated seizures or less frequent seizures may be the result of another underlying disease.

The onset of seizures in dogs suffering from canine epilepsy can begin as early as 6 months of age, or as late as 5 years. Seizures that arise in dogs aged over 5 years may again be the result of an underlying disease, and not a result of epilepsy. The frequency of seizures in epileptic dogs may also increase over time (without treatment). Depending on the severity, epileptic dogs may experience multiple seizures each month. Multiple seizures in a day is a cause for concern (see cluster seizures below).

Canine epilepsy causes seizures as a result of sudden abnormal ‘electrical activity’ in the brain. This unusual activity results in a complete or altered loss of conciousness.

In the majority of cases, the cause of canine epilepsy is unknown (idiopathic), however, in some cases, epilepsy may be the result of a known cause (e.g. scar tissue in brain).

Causes of Canine Seizures

Some of the more common causes of canine seizures are listed below:

• Toxins – For example; antifreeze, toxic plants, excessive chocolate (theobromine) or even lead (peeling lead paint)
• Trauma – A recent head injury can cause scar tissue formation in the brain, which could lead to the onset of seizures
• Meningitis – Inflammation of the tissue surrounding the brain (the meninges) can cause seizures in some dogs
• Encephalitis – Inflammation of the brain, which like meningitis, can cause seizures
• Canine Distemper – A viral disease that can affect the nervous system, causing muscle spasms and potentially, seizures
• Tumours – A tumour in the brain itself or surrounding tissue can be a serious medical issue and can have severe symptoms such as seizures
• Hypoglycaemia – A low concentration of glucose (sugar) in the blood, which can have a mild symptoms (disorientation) or severe symptoms (unconsciousness, seizures)
• Liver disease – In some dogs, the presence of liver disease can cause complications including kidney failure, infection or seizures)
• Epilepsy – Recurrent seizures are usually a result of epilepsy, in the majority of cases the exact cause is unknown (idiopathic)
• Genetics – In some breeds of dog, there is an inherited risk of developing epilepsy (see below), meaning the puppies of epileptic parents (male or female) have an increased risk of developing the disorder themselves

Breeds With an Inherited Risk of Developing Canine Epilepsy

Breeds of dog with evidence to suggested a genetic risk of developing idiopathic epilepsy:

• Beagle
• Boxer
• Cocker Spaniel
• Border Collie
• Dachshund
• Dalmatian
• German Shepherd
• Golden Retriever
• Irish Setter
• Irish Wolfhound
• Labrador Retriever
• Poodle
• Saint Bernard
• Schnauzer
• Siberian Husky
• Welsh Springer Spaniel
• Wire Fox Terrier

See here for more information on the genetics of canine epilepsy.

Types of Canine Seizure

Like humans, there are multiple types of seizure. From the more recognisable ‘General Seizures‘, to ‘Partial Seizures‘ – which can often be difficult to detect in dogs.

General Seizures

General seizures are easily identifiable and highly recognisable, due to their obvious effect on the whole body. This type of seizure results in the rapid relaxation and contraction of entire muscle groups, leading to the body convulsions typically associated with seizures.

This type of seizure is also known as a ‘Tonic-Clonic‘ seizure (or formerly ‘grand mal’). The Tonic-Clonic seizure has 3 identifiable states:

1. Aura – Difficult to detect in dogs, but widely reported in humans; the ‘aura state’ is a sense of foreboding, disorientation or unhappiness before a seizure occurs. In dogs, this is most likely to present itself as a combination of strange behaviours, such as; fatigue, confusion, barking or other unusual behaviour
2. Tonic – This brief state occurs for a matter of seconds and results in the contraction of muscles. The sudden contraction will often lead to collapse or vocalisation (due to air being forcefully expelled from the lungs)
3. Clonic – The most recognisable state, rapid relaxation and contraction of muscles, causes body convulsions

Partial seizures (Focal Seizures)

Partial seizures affect an isolated part of the body, e.g. a limb or facial muscles, which causes twitching in the affect muscle(s).

Complex partial seizures (formerly known as psychomotor seizures) can be much more difficult to recognise. They cause no typical convulsions and only result in unusual behaviour. Commonly reported behaviours associated with these complex partial seizures include; frenzied barking, licking or chewing themselves, staring into space, snapping at invisible objects and accidental defecation or urination.

Like general seizures, partial seizures (both ‘standard’ and complex) are preceded by an aura phase. They also result in impaired awareness and responsiveness.

Seizure Types Requiring Emergency Medical Attention

Cluster seizures – When multiple seizures occur in one 24 hour period, veterinary assistance should be sought. Cluster seizures indicate a more severe underlying problem or epileptic state.

Status epilepticus – A persistent epileptic state that lasts for longer than 5 minutes (a typical seizure would not last longer than this). Status epilepticus can lead to permanent brain damage and requires immediate veterinary attention. This epileptic state may not self-terminate without veterinary aid.

What to Do During a Seizure

When your dog is experiencing a seizure, they will lose consciousness, meaning that your dog is not in a state of suffering; however, you should take some precautions for your own safety and the safety of your dog.

Ensure the immediate area is safe by removing all breakable items or furniture that could fall onto or harm your dog if knocked over. Also, move children in to a separate room until the seizure passes.

Whilst you may feel the need to intervene, you should avoid direct contact with your dog until the seizure has passed. In their epileptic state, they may pose a risk to you and themselves. Owners have reported animals snapping at them during a seizure (out of character behaviour due to a loss of conciousness).

Do not leave your dog, stay with them and observe them until the seizure is over. This is to ensure they safely recover and do not enter status epilepticus (see above).

Treating Canine Epilepsy

An isolated seizure may not be cause for concern, however, treatment will likely be considered when seizures become regular e.g. after second seizure or if seizures occur monthly or more frequently.

In some cases it may be possible to treat an underlying medical condition that is the cause of canine seizures, but in epileptic dogs there is, unfortunately, no cure. Treatment of canine epilepsy involves controlling the seizures by reducing their severity and/or frequency. Some dogs may respond to treatment extremely well and stay seizure free for extended periods of time.

Many owners and vets recommend keeping a ‘seizure journal‘, noting the times, environmental conditions, possible triggers, duration etc. of their dog’s seizures. This can prove extremely useful in controlling your dog’s seizures when combined with effective therapy. There are even apps to help with this process.

The majority of human epilepsy drugs are toxic or ineffective in dogs and other companion animals, leaving us with two primary options for the treatment of the disorder:

1. Phenobarbital – A mild sedative and hypnotic, used as an anticonvulsant to prevent seizures
2. Potassium bromide – An anticonvulsant, (restricted use in cats)

In some cases, these treatments may be combined, especially where seizures are severe or they aren’t as effective individually.

Dogs being treated with these medications should undergo regular blood tests, 2-4 times a year to ensure the correct therapeutic dose is being given. This will allow the vet to determine if the dog is receiving too high or too low a dose. High concentrations of anti-epileptic in the blood can pose a toxicity risk, whilst low concentrations may be ineffective in controlling the seizures.

Side effects

When dogs begin treatment (or when the dosage is increased) for epilepsy, side effects may be worse until the body becomes accustomed to the treatment.

Side effects common to both treatments:

• Increased thirst and appetite
• Mild sedation (reduced alertness)
• Increased frequency of urination
• Instability (especially in the hind legs)

Phenobarbital specific side effects (rare, but considered worse than the seizures it is trying to control):

• May cause liver toxicity (hepatotoxicity)
• Blood abnormalities e.g. Low red/white blood cell count and low platelet count

Dogs undergoing treatment that includes phenobarbital are advised to have blood tests twice a year, to monitor liver health.

Effectiveness of Treatment

For treatment of canine epilepsy to be effective, it is important to maintain a therapeutic concentration of the medication in the blood stream (i.e. ensure the correct concentration of medication in the blood). It is important that you, as the owner, maintains a strict treatment regime as missing a dose of your dog’s medication can negatively affect treatment.

It is also worth noting that once treatment begins, a form of ‘dependency’ develops, stopping treatment can lead to the onset of a seizure.

Dogs that respond well to treatment may be able to have their dosage reduced (reducing the severity of the side effects) – although this will require gradual reduction in dosage over a period of time.

Some owners claim to have had success using an elimination diet – GARD, which you can check out here.

Living with Epileptic Dogs

If you are the owner of an epileptic dog and would like to share some advice with other owners, please leave your comments below. It can be hard initially to keep up with the additional responsibilities of owning an epileptic dog (such as medication and maintaining a seizure journal), but with your help, your dog can live a happy and normal life.

If you are worried about canine epilepsy, you should speak to your veterinarian, who will be able to talk through the options you have and offer more advice on treatment, responsibilities and care.

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Written by James Watts

Editor of PetSci. When I'm not writing, learning, discussing, or reading about animals, you know it's the weekend!