Canine Epilepsy

What It Is, What It Isn’t and What to Do About It

by C.A. Sharp

First published in Double Helix Network News, Summer 2002, Rev. May 2013

Lonny woke up to the bed shaking.  Having grown up in California, his first groggy thought was, “Earthquake!”  He sat up with his heart pounding, awake enough to remember he lived in Kansas now.  But the bed continued to shake.

Oso, his best buddy, his beautiful black tri Aussie, lay moaning beside him.  Something smelled.  Lonny spoke to Oso to reassure him as he fumbled for the bedside light.  It flashed on.  Beside him, Oso convulsed in a seizure.  His dog’s eyes were glazed, his body stiff.  Oso’s legs flailed and his jaws snapped at nothing.  Urine and feces stained the bedspread.

Lonny’s heart thudded in his chest and his eyes blurred with tears.  What was happening to his wonderful dog?  He scrambled out of bed.  Oso lay near the opposite edge, in danger falling off and striking a dresser.  Lonny pulled on the bedspread to move Oso into the middle of the mattress.  He wanted so badly to hold Oso and comfort him, but didn’t dare touch him because of the blindly snapping jaws.  Unable to do anything else, Lonny spoke softly to his friend until Oso’s seizure stopped.

Neither Lonny nor Oso are real, however there are too many Australian Shepherds like Oso and too many people like Lonny who must regularly deal with the horror of watching a beloved dog suffer repeated epileptic seizures.  In the 1980s, epilepsy was only occasionally noted in the breed.  Since the late 1990s it has been one of the Aussie’s most common inherited diseases.

Primary (sometimes called idiopathic) epilepsy is easy to misdiagnose.  Treatment is available, but not without side effects or the risk that the disease will not respond.  Not only are the genetics of it so far unknown, but most affected dogs will not develop the disease until adulthood making it difficult to breed away from.  It scares breeders so much that some insist what happened was not epilepsy or even lie about whether it has occurred in their lines, further complicating efforts to reduce its frequency.  Because it is so common, others turn fatalistic – it’s everywhere, so what can one do?

Inherited epilepsy is the most common neurological disease in dogs.  It is seen in both purebred and mix-breed dogs, but some breeds, like the Aussie, have a much higher incidence than is seen in dogs as a whole, due to the restricted gene pool typical of any purebred population.  The founders of any given breed will have only a subset of all the versions of genes—good and bad—present in the canine species.  Selection over generations for desired traits will limit that gene pool further and not all the genes retained will be for desirable.  If, at some point in a breed’s history, a particular sire or line of dogs becomes predominant, inherited problems may start to arise seemingly out of nowhere simply because attempts to concentrate the desirable genes of select individuals can inadvertently bring together whatever undesirable genes are present.

The term “idiopathic,” often applied to inherited epilepsy, means of unknown cause.  The terminology was developed at a time when no one realized that genes could cause the disease.  Primary epilepsy is a better term; it indicates that the epilepsy is not caused by some other factor.

OTHER CAUSES OF SEIZURES

Body chemistry imbalance
Brian tumor or other brain disease
Infection, esp. with high fever
Medication
Poison
Severe head trauma

Epilepsy is a seizure disorder.  Both epilepsy and individual seizures can be caused by a variety of things:  Head injury, toxic exposure, infections, fever, body chemistry imbalances, and brain disease to name a few.  When a dog has a seizure, the veterinarian’s task is to identify and treat the cause.  A detailed history will be taken to determine whether anything has happened to the dog that might cause seizures or whether it might be suffering from some other disease.   The vet will ask about what the dog has done recently, where it has been, what medications it is taking, whether it showed signs of illness other than the seizure.  If the dog was not presented in a seizure state, as is often the case, the vet will ask for a detailed description of the seizures—what the dog did before, during and after, how often the seizures occur and how severe they are.  Tests will be run to make sure blood counts and body chemistry are normal.  If an injury is suspected, x-rays may be taken.  An MRI might be done to see whether there is any damage or disease in the brain.  If a cause is found, the dog will be treated for that in hopes of relieving or even stopping the seizures.  If there is brain damage, the seizures may continue and require ongoing anti-seizure treatment.  Such a dog would have secondary epilepsy—epilepsy brought about by an identified cause.

If a dog has inherited epilepsy, all tests will be negative.  At this time there is no positive test for this disease and, in Aussies, no DNA test.  It is a diagnosis of exclusion—the ruling-out of all other reasonable possibilities.  Dogs with inherited epilepsy will continue to have seizures at intervals.  The intervals may be as long as weeks to months or as short as once or several times in a single day.   The dog cannot be cured.  It will probably have seizures for the rest of its life.  The seizures may cause cumulative damage to the affected area of the brain.  Seizures sometimes kill.

Because of the risk of cumulative damage from repeated seizures, anti-seizure medication may be necessary.  Any dog that is seizing more frequently than once a month probably should be medicated.  Costs vary depending on the medication and some are very expensive.  They also have serious side effects and require monitoring.  The treating veterinarian must determine which drug or combination of drugs is best for a particular dog.  In many cases, treatment will start with a larger dose to get the seizures under control.  Then, over time, the medication will be adjusted to a minimum effective dose.  Even medicated, epileptic dogs will continue to seize; the point of treatment is to keep it from happening too often.  Medications may need to be adjusted from time to time, and every epileptic dog should have regular veterinary check-ups to monitor the epilepsy as well as drug side effects.  Not every dog will respond to medication.  Sometimes medications need to be changed.  Some dogs may reach a point where they don’t respond to any of the available drugs.

Seizures often develop a pattern, not just in frequency but in what triggers them.  Owners of epileptic dogs should keep a seizure log, noting the date, time, circumstances and severity of the seizure for their own information as well as their vet’s.  If the treating vet has never seen the dog seize, as is often the case, taking a video may be helpful.

KEEP A SEIZURE LOG

Date
Time of day
Severity
Duration
Dog’s behavior before/after
What was going on just before

Some dogs will seize at night while sleeping, others may have a seizure when engaged in particular (often exciting) activities.  Knowing when your dog is likely to seize can help you prevent him from injuring himself during a seizure.

When a seizure starts, other animals and children should be removed from the immediate area.  Remove anything nearby that might be damaged or harm the dog if he strikes against it.  Speak to the dog in soothing, calm tones.  Do not touch the dog or put your hands in or around the dog’s mouth as it might accidentally bite you.  Seizing dogs may react to any touch by snapping and can cause severe injury.

Most dogs will be woozy and disoriented after a seizure.  This may last a couple hours or a few days.  Make sure the dog has a quiet place to rest and discourage other animals or children from bothering the dog until it is feeling normal again.  If you do not feel that the dog is recovering properly, contact your vet.

The vet should be contacted after a seizure to report the circumstances.  A visit may or may not be necessary at that point, but if the dog has a second seizure it should definitely go to the vet for exam and testing.

Living with epilepsy is distressing.  There are support organizations for people whose dogs have epilepsy. (See references at end of article).   Sometimes talking with other people who are dealing with the same problem you are is a big help.  They’ve been there and they know exactly what you are going through.  They may also be able to offer you tips that will help make your life and your dog’s easier as you deal with the disease.

Epilepsy presents one set of problems to a dog owner and another to a breeder.   It is a terrible disease and not something any breeder wants to produce, but avoiding it can be difficult.   We don’t know exactly how it is passed from one generation to the next.  Dogs may not develop the disease until they are old enough that they may already have offspring.  Failure by some to disclose information can make it impossible for others with related dogs to avoid risky crosses.

While primary epilepsy is now recognized as inherited, the mode of inheritance in Aussies is not yet known.  There are multiple genetically distinct types of epilepsy, though any one breed will likely have only a single type.    In Australian Shepherds, it is clearly not dominant or one would see it following clear lines from parent to offspring generation after generation.  A sex-linked condition would result in many more affected males than females, which is not the case.  Several years of genetic research has failed to turn up a single-gene cause and the most recent work indicates that multiple genes may be involved.  Therefore, a healthy parent can produce affected offspring and both parents must be carriers though the contribution of each may vary.

Because this disease is so devastating to the owner as well as the affected dog and because it can sometimes kill, the author strongly discourages the continued use for breeding of any dog that is a first-step relative of an epileptic dog.  This would include parents, siblings and offspring.   More distant relatives will need to be bred with care because they have a potential for carrying epilepsy genes.  The closer they are related to the affected dog, the greater the risk.

CONTROL FURTHER SPREAD OF EPILEPSY

  • Do not breed first-step relatives (parents, siblings, offspring) of affected dogs.
  • Support research projects by providing data on affected dogs and their relatives.
  • If a test becomes available, screen all at-risk breeding stock.
  • Be open with other breeders if epilepsy has occurred in your dogs.

Relatives of epileptic dogs are also at risk for having epilepsy themselves.  If such a dog is intended for breeding, one should not do so until it is at least three or four years old.  Most affected dogs will begin to have seizures around two years of age.  Aussies as young as 8 months old have been diagnosed with inherited epilepsy.  Dogs over four years of age will sometimes develop the disease, but this is relatively rare.  [NOTE:  In Aussies, baby puppies do not exhibit signs of primary epilepsy.  If a young puppy is having seizures there is some other cause.]

If this disease is to be controlled in our breed, breeders need to make it a high priority.  Pedigrees of affected dogs should be shared openly.  The breed community needs to be supportive of those who come forward, and discourage those who advocate shunning them and their dogs.  The more open information is exchanged amongst breeders, the better chance they will have to avoid breeding two high-risk dogs together.

Knowing the mode of inheritance and being able to positively identify carriers would be a great boon for breeders.  But discovering the mode of inheritance and developing a screening test requires research.  Research requires data on affected dogs along with DNA samples.  Please support ongoing epilepsy research studies both by providing samples and through assisting ASHGI with financial support.  This is the only way we can get a DNA screening test for this disease.

With a DNA screening test breeders would know ahead of time which dogs will develop the disease so they can be monitored for care and will not be bred.  Knowing which dogs carry epilepsy genes enable breeders to avoid producing affected dogs.  As frequency of the disease is reduced, preference can be given to dogs that are not carriers, gradually reducing the frequency of the undesirable genes without sacrificing the good qualities possessed by carrier dogs.

A day may come when there are no more Osos and the Lonnys of the world will no longer have to kneel beside their stricken dogs waiting for the seizure to end.  But before we can get there, breeders need to make the control of epilepsy a major priority, supporting the owners of affected dogs and working with vets and researchers toward genetic control of the disease.

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