What is epilepsy?
Epilepsy is a chronic condition that causes repeated seizures (which may be described by terms such as 'fits' or 'funny turns'), and is the most common chronic (long-term) neurological disorder in dogs. It affects an estimated 0.6-0.7% of all dogs in the UK alone (around 1 in 130 dogs). In most cases epilepsy is a lifelong disease.
What happens during a seizure?
A seizure occurs when there is abnormal electrical activity in the brain which leads to sudden but short-lived changes in a dog's behaviour and/or movement.
What are the signs my dog may be epileptic?
Your vet may suspect that your dog has epilepsy if they have at least two unprovoked epileptic seizures more than 24 hours apart. It can be difficult for vets to tell the difference between seizures and other health problems, so providing them with a thorough description of the abnormal event, or ideally a video recording, can help them in their diagnosis.
Characteristics of epileptic seizures
The three main characteristics of epileptic seizures are:
- loss of voluntary control, often seen with convulsions (jerking or shaking movements and muscle twitching)
- irregular attacks that start and finish very suddenly
- attacks that appear very similar each time and have a repetitive clinical pattern
Are there different types of seizures?
There are several types of epileptic seizure, but how they affect one dog can be different to how they affect another. Some dogs have more than one type of seizure, and not all seizures involve convulsions.
Most epileptic fits usually:
- happen quite suddenly without warning
- last a short time (often only a few seconds or minutes)
- stop by themselves
Injuries can happen during seizures, but most dogs do not hurt themselves and do not need to go to the vet unless epilepsy has not been diagnosed.
Below are the names of the different types of seizures, along with descriptions of what happens during each type of attack:
Focal seizures (twitches, blinking, salivation, behaviour changes)
These occur in only one half of the brain and within a particular region. How these types of seizure present themselves depends upon where in the brain the abnormal electrical activity started, and the function of that part of the brain. Focal epileptic seizures can present as:
- episodic movements ("motor" signs) e.g. facial twitches, rhythmic blinking, head shaking or repeated muscle contractions of one extremity
- autonomic signs (arising from the autonomic nervous system) e.g. excessive salivation, vomiting, dilated pupils
- behavioural signs (episodic changes in the dogs behaviour) e.g. restlessness, anxiety, attention seeking, unexplainable fear behaviour
Generalised seizures (stiffening, rapid jerking)
These occur within both sides of the brain. Generalised seizures may occur alone or may start as a focal seizure (detailed below) and evolve into a generalised seizure. In most cases of generalised seizures the dog loses consciousness, and salivation, urination and defecation may occur. Motor movement occurs on both sides of the body. Aspects of generalised seizures are often termed tonic, clonic, tonic-clonic and myoclonic. These terms are defined below:
- Tonic: increase in muscle contraction (stiffening) lasting from seconds to minutes
- Clonic: involuntary rapid and rhythmic contractions of muscles (jerking)
- Tonic-clonic: a sequence of a tonic phase followed by a clonic phase
- Myoclonic: sporadic jerks usually on both sides of the body
Generalised seizures can also be non-convulsive, such as atonic seizures (also called drop attacks), which result in a sudden and general loss of muscle tone which usually causes the dog to collapse.
Focal seizure evolving into a generalised seizure
This is when a generalised seizure follows on from a focal seizure. This is the most common seizure type observed in dogs. The focal seizure is often very short (few seconds to minutes) and the secondary generalisation follows rapidly. The focal seizure may be difficult to detect due to its brief nature and it is important to tell your vet what happened before convulsions started, to help them determine what type of seizure your dog is having.
What causes epilepsy?
A number of different underlying diseases and other factors can cause seizures leading to epilepsy. Generally, epilepsy can be classified as 'structural' (where an underlying cause can be identified in the brain) or 'idiopathic' (where no underlying cause can be identified, and a genetic predisposition is often presumed or the cause is unknown).
Idiopathic epilepsy (no known cause)
Idiopathic epilepsy usually affects young to middle age dogs (6 months to 6 years old) in which no underlying cause for repeated seizures can be found. Idiopathic epilepsy is often assumed to be due to a combination of genetic and environmental factors. Some breeds may be more predisposed to epilepsy than others and their prevalence may be higher than others. Epilepsy may run in some families and pedigree studies have demonstrated a hereditary basis for some types of epilepsy in a number of breeds.
To diagnose idiopathic epilepsy, known causes, such as certain diseases, must first be ruled out. The diagnosis should be based on your dog's medical history, a neurological examination and laboratory tests (blood and/or urine). Further assessments such as imaging the brain using MRI and analysing your dog's cerebrospinal fluid, may be recommended by your vet to detect abnormalities that could be causing the seizures.
Structural epilepsy (caused by a known issue in the brain)
In other dogs experiencing seizures, an underlying cause can be found in the brain. This includes problems with blood supply, including obstructions, as well as bleeding, inflammation, infection, trauma, developmental problems, brain tumours and degenerative brain diseases. These abnormalities can be confirmed by either MRI and/or cerebrospinal fluid analysis. In addition to these structural causes, metabolic disorders of the brain can lead to a change in its structure and neuronal degeneration. For example, Lafora's disease (which affects some Miniature Wire Haired Dachshunds, Basset Hounds and Beagles) is caused by a gene defect that leads to a 'storage disease' (where a toxic substance accumulates in cells), changing the structure of the brain and leading to seizures.
Reactive seizure (temporary changes to the brain)
A reactive seizure usually occurs in response to a temporary problem in brain function, which may be as a result of metabolic changes or poisoning - which is reversible when the cause or disturbance is rectified.
What should I do if my dog has a seizure?
- It is important that you stay calm
- Most seizures are brief, and dogs are usually totally unaware of them
- Affected dogs are not likely to suffer during the seizure, even if they appear violent
- Make sure you and your pet remain safe by moving any furniture out of the way, so that your pet cannot hurt themselves
- Under no circumstances should you put anything in your pet's mouth, including your hands
- Your vet may prescribe 'emergency medication' to reduce the length of an epileptic episode
Observing your dog's seizure
Most seizures last only one to two minutes, but it is a good idea to time the seizures so you are sure of its length. It is very helpful to observe the seizure carefully. In particular, what were the first signs? Was one side of the body affected first? What sort of movements did your pet exhibit? e.g. paddling movements, shaking, chewing or chomping. Records of these observations along with your seizure diary will be very useful information for your vet.
Length, frequency and severity of seizures
How often a dog with epilepsy experiences seizures can vary greatly between dogs and over an individual dog's lifetime. Recording how often your dog has seizures is important to track how well their treatment is working, and so your vet can alter their treatment if necessary. Some dogs experience seizures very close together in time (e.g. more than one in a day), seizures that are very long, or seizures that immediately lead to more seizures, which they do not return to normal in between. These types of seizure pose a particularly high risk to your dog's health, can be life-threatening and an emergency:
Cluster seizures (two or more seizures in 24 hours)
A cluster seizure occurs when a dog has two or more seizures within a 24-hour period. Cluster seizures occur in around ⅓ to ¾ of dogs with idiopathic epilepsy. Some breeds of dog may be more prone to cluster seizures including the German Shepherd Dog, Border Collie, Boxer, Cavalier King Charles Spaniel, Staffordshire Bull Terrier and Labrador Retriever. If your dog has cluster seizures, emergency medication may be prescribed by your vet for home use. These medications are administered if a cluster seizure occurs, to try and stop the seizure and to prevent more from occurring. During a seizure, you should never attempt to put anything in your dog's mouth, including your hands. Although cluster seizures can be treated at home with medication, such as rectal diazepam or levetiracetam pulse therapy, you should also contact your vet for further advice and/or changes in treatment to try and avoid clusters occurring in the future.
Status epilepticus (seizures longer than five minutes, or two seizures without the dog returning to "normal" in-between)
Status epilepticus is classed as either:
- a seizure that lasts longer than five minutes, or
- where two or more individual epileptic seizures occur, between which the dog does not return to 'normal' and regain full consciousness
Immediate treatment is necessary because status epilepticus can cause permanent neurological damage or even death. If status epilepticus occurs in your dog, immediately contact your vet for emergency treatment. Emergency treatment includes your vet administering high doses of medications that try to stop the seizure and minimise damage to your dog's brain and body. Although seizures are distressing to witness, you should always try to stay calm when a seizure starts and time how long it lasts, so you know whether a seizure is lasting a particularly long time, and are prepared to contact your vet if status epilepticus occurs.
What can trigger my dog's epilepsy?
Some dogs may appear to have 'triggers' that lead to a seizure, while others do not. Identifiable triggers may differ from dog to dog. In people with epilepsy, common triggers include:
- lack of sleep
- not taking medication
Stress is a trigger commonly reported by owners, and may be caused by a variety of situations including changes in the environment, changes in routine, car rides, thunderstorms, and visits to the vet to name a few. Other owners report certain foods or medications seem to trigger seizures in their dog. Keeping a seizure diary may help identify triggers in your dog.
What treatment options are available and can epilepsy be cured?
In most cases, epilepsy in dogs cannot be cured. Maintaining a seizure-free status without causing unacceptable side effects is the ultimate goal of antiepileptic drug (AED) therapy. This balance is achieved in 15-30% of dogs. The goal of medical treatment is therefore to improve your dog's quality of life by minimising how frequently the attacks occur and how severe they are. Additionally, the medications chosen for this should not cause serious side effects.
Antiepileptic drug (AED) therapy
If your vet recommends commencing AED therapy, ensure you discuss this thoroughly so that you understand the importance of this treatment and why it is necessary. Your vet will be able to support you with this treatment, and regular health checks should be arranged so you can both monitor for adverse effects of the idiopathic epilepsy or the medication. Once started, AED treatment is continued indefinitely, in most cases for the rest of your dog's life, with periodic health checks and blood tests to ensure correct drug dosage, treatment efficacy and minimal treatment-related side effects.
It is very important that you:
- give your pet their medication at the same time every day
- give them the correct dosage of medication
- continue their treatment and do not stop without first discussing with your vet
Which AEDs will my dog be prescribed?
Your vet will be able to advise you as to which antiepileptic drug (AED) is most suited to treating your dog's epilepsy. Factors that may influence your vet's decision may include the type of seizure your dog experiences, how often they seizure, and if they have any problems with their kidneys or liver. The first medications your vet can legally prescribe to treat your dog's epilepsy in the EU are either imepitoin or phenobarbital.
If the desired reduction in seizures is not seen with the 'first line' medications, they may choose to 'add-on' potassium bromide as a second medication. There are several AEDs used to treat epilepsy in humans that are being used to treat epilepsy in dogs; however, these medications can only be used if the approved treatments have failed.
Always keep your dog on a constant diet as changes to what your dog eats can change blood levels of certain drugs. Furthermore, new diets are currently being developed, which might help to improve seizure control even further.
How do I know if the drugs are working?
Antiepileptic drug treatment is generally considered to be successful if the frequency of their seizures is reduced by at least half, though seizure freedom should be aimed for. To determine whether the medication is working, an accurate seizure diary is required. From this, you can track patterns in your dog's seizure frequency and severity to see if improvements are occurring.
How can I monitor if the drugs are working?
The Royal Veterinary College (RVC) has created an app (Pet Epilepsy Tracker) which allows owners to electronically track seizures on their smart phone.
Do these drugs have side effects?
Your dog may experience side effects of their AED treatment. The effects may occur soon after treatment starts or their dose is increased. These effects generally disappear or decrease in the subsequent weeks due to your dog's body developing a tolerance to these drugs. In some cases, these side effects persist and must be monitored to ensure their severity does not compromise your dog's quality of life. Side effects vary with different AEDs.
What are the common side effects of antiepileptic drugs?
Common, potential side effects of AED treatment include:
- increased appetite and thirst
- weakness of the back legs
- weight gain
- behavioural changes
If your dog stops having seizures, or your dog experiences life-threatening side effects, then your vet may recommend that the AED treatment is stopped. Never stop treatment immediately, as this can in itself cause seizures and status epilepticus. Please consult your vet prior to changing medication.
Where can I find further support and resources?
- RVC Pet Epilepsy Tracker is free to download to Apple devices
- RVC's Canine Epilepsy Research Facebook page can keep you up to date with new research and studies in this area
- A veterinary neurology specialist can help you to help your pet with epilepsy. In Europe, browse this list of ECVN-accredited neurologists, and in the US, please refer to this list of ACVIM-accredited neurologists
- For more information on canine epilepsy, the International Veterinary Epilepsy Task Force (IVETF) has come together to set out a unified and standardised set of guidelines for the research, diagnosis and treatment of canine and feline epilepsy for the first time ever in veterinary medicine. Seven consensus statements from the group have recently been published
- The Royal Veterinary College has recently published a review paper on the impact of epilepsy on canine quality of life, accompanied by a free to access podcast
This article was written by Dr. Rowena Packer and Professor Holger Volk, both from the Royal Veterinary College.
Dr. Rowena Packer is a Clinical Investigations Postdoctoral Researcher at the Royal Veterinary College. Her current research focuses on the treatment of canine epilepsy and its impact on canine behaviour and welfare.
Professor Holger Volk is Clinical Director of the RVC Small Animal Referral Hospital and Professor of Veterinary Neurology and Neurosurgery at the Royal Veterinary College. His main research interests are chiari-like malformation and syringomyelia and the treatment of canine and feline epilepsy.
Think your dog may be affected?
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We're not a veterinary organisation and so we can't give veterinary advice, but if you're worried about any of the issues raised in this article, please contact your local vet practice for further information.
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