What is idiopathic epilepsy?

Seizures are the result of a disturbance in the electrical activity of brain cells. They can occur for a variety of reasons, in any breed of dog. Epilepsy is the term used for recurrent seizures where no underlying disease process can be identified as the cause (also called idiopathic epilepsy).

Inherited idiopathic epilepsy is genetically transmitted in some breeds of dogs. Seizures typically begin between 1 and 3 years of age. Before or after this age, the seizures are more likely caused by an active disease process, such as infection, trauma, a metabolic disorder, or a tumour.

How is epilepsy inherited?

The mode of inheritance is unknown, and varies between breeds. In some breeds, it appears that more than 1 gene is involved.

What breeds are affected by epilepsy?

Instances of idiopathic epilepsy have been reported in nearly all breeds. However there is an increased risk, and evidence for an inherited basis, in the following breeds: Belgian tervueren (a high incidence), beagle, Bernese mountain dog, Brittany spaniel, cocker spaniel, collie, German shepherd, golden retriever, Irish setter, keeshond, Labrador retriever, poodle (all sizes), miniature schnauzer, Saint Bernard, wirehaired fox terrier

For many breeds and many disorders, the studies to determine the mode of inheritance or the frequency in the breed have not been carried out, or are inconclusive. We have listed breeds for which there is a consensus among those investigating in this field and among veterinary practitioners, that the condition is significant in this breed.

What does epilepsy mean to your dog & you?

The effects of a seizure depend on the part of the brain involved. Typically there is a change in behaviour (eg. confusion, fear, rage), consciousness (the animal may or may not lose consciousness), motor activity (rigid or jerky muscle spasms, or paddling), and autonomic activity (salivation, urination, and defecation). Changes in sensory function may lead to pawing at the face, tail chasing, or biting at part of the body or the air.

Seizures may be partial or generalized, and mild or severe (grand mal). A dog experiencing a mild generalized seizure might be confused, show weakness and some muscle tremors, and look to the owner for reassurance. A dog in a grand mal seizure will be unconscious, with rigid or jerking limbs, and involuntary salivation, urination, and defecation.

Seizures vary in frequency as well, from very occasional to almost constant. Status epilepticus is a series of seizures in rapid succession, or 1 continuous seizure. This is a medical emergency which requires immediate veterinary attention.

It is common for a dog to show a change in behaviour such as hiding or attention-seeking for hours or even days before a seizure (called the prodrome or aura). Abnormal behaviour associated with fatigue, depression, hunger, thirst, or hyperactivity may last for days afterward (post-ictal phase).

How is epilepsy diagnosed?

You may not recognize that what has occurred in your dog is a seizure (especially if mild), and your dog will likely be back to normal by the time you see your veterinarian (except in the case of status epilepticus).  Thus your description of the abnormal activity you observed is very important.

In order to determine if seizures are due to an underlying disease or are a result of idiopathic inherited epilepsy, your veterinarian will consider the age and breed of your dog and the changes you observed, do various diagnostic tests to rule out other possible causes, and ask questions such as whether your dog may have been exposed to any toxins or possibly received a head injury.

The sudden onset of frequent seizures usually indicates an active brain disease, whereas otherwise normal animals that have a few seizures a year likely have idiopathic epilepsy.

How is epilepsy treated?

Treatment depends on factors such as the severity and frequency of the seizures. A dog that experiences the occasional mild seizure probably needs no treatment other than watchfulness on the part of the owner. Grand mal seizures or status epilepticus, at the other extreme, require emergency medical treatment to sedate or anesthetize the dog, and to prevent the brain damage associated with prolonged seizure activity.

Once your veterinarian has determined that your dog has idiopathic epilepsy (ie. no specific cause that can be treated), s/he will likely recommend regular medication to control seizures if they occur more than once a month or in clusters, or if your dog has experienced a grand mal seizure. Phenobarbital is the drug most commonly used and it is safe, effective and inexpensive. Your veterinarian will work with you to determine the lowest effective dose for your dog. You will be asked to keep careful track of any seizures as well as all drugs given. Blood levels of phenobarbital should be measured periodically, as well as indicators of liver and kidney function. With this monitoring, most dogs with idiopathic epilepsy can lead a normal life. Dosages may need to be adjusted if there is a change in seizure frequency or severity, or if medication is given for another reason. If seizures were initially readily controlled and none has occurred for 6 to 9 months, your veterinarian may very gradually reduce the dosage, and sometimes ultimately discontinue the use of anticonvulsants.

Phenobarbital is not always effective and there are other anticonvulsants that can be tried. Acupuncture is another alternative which may be effective as a first line of treatment, or when use of anticonvulsants fails to control the seizures. A veterinarian specializing in acupuncture should be consulted.  

Breeding advice

Dogs that have experienced seizures, and their parents and siblings, should not be used for breeding.

The Institute for Genetic Disease Control in Animals http://www.vetmed.ucdavis.edu/gdc/gdc.html maintains an open research database for idiopathic epilepsy in the Irish setter, Labrador retriever, and Bernese mountain dog. The Keeshond Club in Britain has operated a genetic counselling programme for keeshonds since 1989. The American Belgian Tervueren Club has also participated in a programme to gain information to reduce the incidence of epilepsy in this breed.

FOR MORE INFORMATION ABOUT THIS DISORDER, PLEASE SEE YOUR VETERINARIAN.

Resources

Institute for Genetic Disease Control in Animals:  http://www.vetmed.ucdavis.edu/gdc/gdc.html

Hall, S.J.G., Wallace, M.E. 1996. Canine epilepsy: a genetic counselling  programme for keeshonds. Veterinary Record. 138: 358-360.

Chrisman, C.L. 1995. Seizures. In S.J. Ettinger and E.C. Feldman (eds.) Textbook of Veterinary Internal Medicine, pp. 152-156. W.B. Saunders Co., Toronto.

Parent, J. 1996.  Signalment and seizure pattern in the diagnosis and treatment of recurrent seizures.  ACVIM-Proceedings of the 14th Annual Vet. med. Forum. p. 326-327.

Copyright 1998 Canine Inherited Disorders Database. All rights reserved.
Revised: October 30, 2001.

This database is a joint initiative of the Sir James Dunn Animal Welfare Centre at the Atlantic Veterinary College, University of Prince Edward Island, and the Canadian Veterinary Medical Association.