Epilepsy in Dogs
by Dr. Audrey Harvey, BVSc (Hons)
Epilepsy in dogs is defined as repeated seizures that occur over a period of several weeks or months. Approximately 1% of dogs suffer from ongoing convulsions and need regular medication to allow them to lead a normal life.
Also known as convulsions or fits, seizures are sudden abnormalities of electrical activity in a dog's brain which affect their consciousness and muscle movement. They can last up to several minutes, and are usually very frightening for their owner. In many cases, they happen just once, and don't cause any long term problems. While seizures themselves aren't usually fatal, they can lead to misfortune because an affected dog has no control over where they have a fit.
Causes of Epilepsy in Dogs
Epilepsy is categorized into two groups. Primary epilepsy in dogs is associated with no physical brain disease, and it usually occurs in young dogs from 1 to 4 years old. Dogs are often born with this condition, and they are completely normal between seizures.
Secondary epilepsy in dogs results from brain damage due to infection, toxins or trauma. It occurs in dogs of all ages, and there may be signs of brain disease between their fits.
The age at which a dog develops epilepsy can sometimes give an indication of the cause. Young dogs are most likely to convulse because of congenital brain problems or being exposed to toxins. Senior citizens develop epilepsy because of metabolic disease or brain cancer. Infectious diseases such as distemper can cause inflammation of the brain in dogs of any age. Fortunately, a vaccination is available to protect our pets from this disease.
There are breeds that appear predisposed to epilepsy. A genetic cause is suspected in Labrador Retrievers, Golden Retrievers, Keeshonds, Belgian Tervueren and Poodles. In the Belgian Tervueren, it appears that there is one main gene responsible for in the disease, whereas in the Retriever breeds, several genes seem to be involved.
Clinical Signs of Epilepsy in Dogs
Owners of dogs that have several seizures may be able to recognize an aura – a subtle change in their dog's behavior that indicates a seizure is just about to happen. Their dog becomes restless and starts to salivate.
The common signs of seizures that we are most familiar with are rigidity, loss of consciousness, frothing at the mouth and paddling of the legs. However, dogs can also bark and howl and pace the floor during a convulsion. They may even become temporarily blind. Often, they lose control of their bowels and bladder.
These are known as “grand mal” seizures, and usually only last a few minutes. However, that can seem like forever to a frightened and distressed owner. Afterward, their dog appears disoriented and confused, and this can last for several hours.
Some dogs have focal, or “petit mal” seizures. The symptoms depend on what part of the brain is affected, and may include twitching of the face or constant blinking. There isn't usually any loss of consciousness during this type of seizure. Focal seizures that affect the part of the brain which control behavior can cause uncontrollable aggression or even snapping at the air, known as “fly catching”.
First Aid for Seizures in Dogs
If your dog has a seizure, it's important that you don't panic. Move any obstacles out of the way so they don't bump into anything, and put a blanket over them. If you are worried about them hurting themselves, then you can gently hold them still. They don't need anything put in their mouth so stay well away from that end of their body. They have no control over what they are doing, and they may inadvertently bite you.
When they have recovered from their seizure, call your veterinarian or the emergency center for advice. They may recommend you bring your dog in for sedation, particularly if he is having repeat seizures.
Diagnosing Epilepsy in Dogs
When a dog is taken to the vet because they have had a seizure, they will firstly have a full examination with blood and urine tests to try and identify the cause. Their owner will be asked about whether they have been exposed to toxins, or if they have had any other signs of illness. Further evaluation depends on the results of these tests, and the dog's age and lifestyle. They can include x-rays, analysis of the fluid surrounding the brain, and CT or MRI scans.
Primary epilepsy is a diagnosis of exclusion. If all the other causes of a dog's seizures have been ruled out, then a diagnosis of primary epilepsy is made.
Treating the Epileptic Dog
When testing has identified a cause of a dog's convulsions, then it must be managed appropriately. Anti-convulsant medication can be used to prevent seizures while they are recovering from their illness. For dogs with primary epilepsy, the main treatment is long term anti-convulsants.
If a dog has had one seizure, and all tests are normal, most veterinarians will suggest a “wait and see” approach. If more convulsions occur, it's time to start treatment, particularly in large breeds of dogs. It appears that seizures are more severe and can be harder to control in these dogs.
• The drug that veterinarians usually reach for first is phenobarbital. It is very effective, but can cause increased thirst, wobbliness and lethargy. Long term use may lead to liver disease.
• Potassium bromide is another popular choice. It can cause similar side effects as phenobarbital, and should be given with food to prevent an upset stomach.
• These drugs can be used in combination for dogs with epilepsy that is difficult to control. Although their seizures stop, they often show an increase in side effects.
• Primidone is an anti-epileptic drug that is used in humans, and can be prescribed for dogs. However, in the body it is metabolized to phenbobarbital, so there isn't any real advantage over using phenobarbital in the first place.
• Acupuncture has been used both on its own and together with anti-convulsant drugs. However, its benefits haven't been proven. If a dog's owner is interested in alternative medicines, then they can be referred to a veterinarian with experience in this area. Natural therapies can still have side effects, and they can also interact with other drugs, so they need to be used with care.
It's important to weigh up the risks and benefits of medication, especially if the seizures are mild and don't occur very often. Most dogs who are prescribed drugs to manage their epilepsy will need to take them for the rest of their life. They will need blood tests once or twice yearly to make sure they are being given the correct dose of the drug, and to check that their liver is coping with the medication.
Because of the possible hereditary nature of primary epilepsy in dogs, any affected dogs should be neutered. This can also help prevent seizures in female dogs, as the hormonal changes that occur with estrus make seizures more likely.
If a dog hasn't had a convulsion for at least 6 months, then it is possible to try and wean them off their medication. Treatment must not be stopped suddenly, because this in itself can trigger withdrawal seizures. If they start having convulsions again, then they need to stay on their treatment. Dogs with secondary epilepsy may be able to stop treatment when the disease that caused the seizures has been treated.
Epilepsy in dogs is a scary disease, but it needn't change your dog's life. With modern medication and careful monitoring, dogs with this condition can still enjoy most of the activities that dogs love.
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