CANINE SEIZURES - AN OVERVIEW, CAUSES AND TREATMENTS

AN OVERVIEW

What is Canine Epilepsy?

Canine Epilepsy is a chronic condition characterized by recurrent seizures. Although seizures are always abnormal events, not all seizures in dogs are caused by canine epilepsy.

Canine Epilepsy is a disorder of the brain where abnormal electrical activity triggers further uncoordinated nerve transmission. This uncoordinated and haphazard nerve tissue activity scrambles messages to the muscles of your dog's body and the coordinated use of the muscles is then inhibited.

Because there are many causes of chronic recurrent seizures in dogs, canine epilepsy is not a specific disease or even a single syndrome, but rather a diverse category of disorders. Canine Epilepsy is broadly divided into idiopathic and symptomatic disorders. Idiopathic Epilepsy, also called primary epilepsy, means that there is no identifiable brain abnormality other than seizures. Symptomatic epilepsy (also called secondary epilepsy) is seizures that are the consequence of an identifiable lesion or other specific cause.

Most dogs with idiopathic epilepsy suffer their first seizure between the ages of one and five years of age. A genetic basis for idiopathic epilepsy is strongly suspected in several breeds including the Beagle, Belgian Tervuren, Keeshond, Dachshund, British Alsatian, Labrador Retriever, Golden Retriever and Collie. Idiopathic canine epilepsy may have an inherited basis in other breeds also.

The Seizure
Watching a beloved dog in the throes of a grand mal seizure is one of the most terrifying scenes you can witness. A seizure refers to the involuntary contraction of muscles. The seizure is caused by an electrical storm in the brain. Seizures can be broken into two types, generalized and partial. In a generalized seizure, the electrical storm appears everywhere at once. In a partial seizure, the abnormal electrical impulses begin in a small area of the brain.

Generalized, tonic-clonic (formerly called grand mal) seizure: The seizure begins with contraction of all skeletal muscles and loss of consciousness. The dog usually falls to his side with the legs stretched out and the head back. This is the tonic portion of the seizure. Sometimes he will vocalize or have facial twitching. Vocalizations are involuntary and do not indicate pain. Often the dog will drool excessively, urinate, defecate or eliminate his anal glands. The tonic portion of the seizure is usually very brief and gives way to the clonic phase of the seizure. Once the clonic phase begins the dog will have rhythmic movements. Typically this consists of clamping the jaws and jerking or running movements of the legs.

Following the seizure, the dog may lay motionless for a brief period. Eventually he will get up on his feet and may appear to be perfectly normal, but typically will show signs of post ictal behavior. These signs may include blindness, disorientation, pacing or running about the house bumping into things. The post-ictal behavior can last anywhere from hours to days after a seizure.

Not all generalized seizures follow this pattern. Another type of generalized seizure is the tonic seizure, in which motor activity consists only of generalized muscle rigidity without the clonic phase. Less common are clonic seizures where there is no tonic phase and some dogs suffer milder generalized tonic-clonic seizures in which consciousness is maintained.

Partial seizures: Partial seizures are also called focal seizures and as the name indicates, the electrical storm is affecting only a part of the brain. A partial seizure may stay localized or it may expand to the whole brain and cause a tonic-clonic seizure. Because the seizure starts in only a part of the brain, an underlying disease or injury is highly suspected. A partial seizure may remain localized or spread to other parts of the cerebral cortex producing a sequential involvement of other body parts.

Partial seizures are classified as simple focal seizures when consciousness is preserved and as complex focal seizures when consciousness is altered. Any portion of the body may be involved during a focal seizure depending on the region of the brain affected.

In a simple partial seizure, the area of the brain that is affected is the area that controls movement. Usually the face is affected, resulting in twitching or blinking. This is usually limited to one side of the face. If the seizure spreads, other parts of the body on that same side will be affected. The dog is usually alert and aware of his surroundings.

A complex partial seizure will originate in the area of the brain that controls behavior and is sometimes called a psychomotor seizure. During this type of seizure, a dog’s consciousness is altered and he may exhibit bizarre behavior such as unprovoked aggression or extreme irrational fear. He may run uncontrollably, engage in senseless, repetitive behavior or have fly-snapping episodes where he appears to be biting at imaginary flies around his head.

Cash WC, Blauch BS: Jaw snapping syndrome in eight dogs. JAVMS 175:179, 1979
Parent JM Seizures, Small animal medicine 735:741, 1991
Thomas WB: Idiopathic Epilepsy in Dogs. Vet Clinics of N. Amer. Small Animal Practice 183:206, 2000

SEIZURES: THEIR CAUSES AND TREATMENT
Seizures are the result of muscle responses to an abnormal nerve-signal burst from the brain. They are a symptom of an underlying neurological dysfunction. Toxic substances, metabolic or electrolyte abnormalities and/or imbalances cause an uncoordinated firing of neurons in the cerebrum of the brain, creating seizures from mild "petit mal" to severe "grand mal."

Stages of seizures:
There are four basic stages to a seizure:
~ The Prodome: may precede the seizure by hours or days. It is characterized by changes in mood or behavior.
~ The Aura: signals the start of a seizure. Nervousness, whining, trembling, salivation, affection, wandering, restlessness, hiding and apprehension are all signals.
~ The Ictus: the actual seizure. A period of intense physical activity usually lasting 45 seconds to 3 minutes. The dog may lose consciousness and fall to the ground. There may be teeth gnashing, frantic thrashing of limbs, excessive drooling, vocalizing, paddling of feet, uncontrollable urination and defecation.
~ The Post Ictus: after the seizure the dog may pace endlessly, appear blind and deaf and eat or drink excessively.

Causes:
The cause can be anything that disrupts normal brain circuitry:
~ Idiopathic Epilepsy, meaning "no known cause" and possibly inherited. This is also referred to as Primary Epilepsy. Check history or pedigree and make sure your veterinarian has looked for possible underlying factors. Seizures caused by underlying factors are referred to as Secondary Epilepsy.

~ Congenital hypoglycemia (low blood sugar)
~ Hypothyroidism (low thyroid function)
~ Infections causing brain damage (such as canine distemper, cryptococcosis)
~ Ingestion of toxins (such as lead paint chips, insecticides)
~ Brain tumors
~ Portosystemic shunts (improperly routed intestinal blood vessels bypass the liver - one of the body's important waste-product detoxifiers)
~ Vaccinations

Types of Seizures:
~ Mild (Petit Mal) can be a simple as momentarily staring into space or upward eye movement.

~ Moderate (Grand Mal) occurs when the dog falls down, loses consciousness and extends its limbs rigidly. Paddling of limbs, salivation followed by possible loss of control of bladder and bowels and vocalization (blood curdling scream) may follow. This may occur for 1-3 minutes and is most often followed by a period of restlessness, pacing, bumping into objects and loss of balance. Post Ictal period: The dog is conscious but may appear deaf, blind and disoriented. Great care must be taken to prevent the dog from injuring itself at this time.

~ Status Epilepticus can occur as one continuous seizure lasting 10 minutes or more or as a series of multiple seizures in a short time with no period of normal consciousness intervening. This may be life threatening.

~ Cluster Seizures are multiple seizures within a 24 hour period time. This may also be life threatening. It is often difficult to distinguish between the two types and veterinarian assistance is imperative. Rectal Valium is extremely useful in breaking cluster seizures. Please see information regarding this on our website at these links: Home Treatment with Rectal Diazepam and Home Treatment with Rectal and Oral Valium/Diazepam.

Post Seizure Treatments:~ To Reduce Post Ictus Pacing: As soon as your dog has regained consciousness and can safely eat, feeding a small amount of Breyers All Natural vanilla ice cream (a teaspoon for small dogs; a tablespoon for medium dogs; two tablespoons for large dogs) can restore normal blood sugar levels. A seizure may drop blood sugar levels and low blood sugar levels can cause more seizures. A seizure to your dog is equal to your running the Boston Marathon so you will need to replace lost energy by feeding a full meal after the ice cream and then giving a couple of handfuls of kibble or pasta or rice with a little butter every hour. Feeding a small amount of carbohydrates every hour will keep blood sugar levels stable. It is important to remember that your dog will be ravenously hungry so you will need to feed very small amounts at a time either with your fingers or in a bowl so they do not inhale the food and cause aspiration pneumonia. Watch your fingers as you feed them - when dogs are this hungry and recovering from seizures, they can bite you without ever realizing it.

The use of Bachs Flower Essence Rescue Remedy® (found in many health food stores) has been found to be extremely useful in some cases when given at this time. Simply put four drops of the Essence into the dog's mouth after the seizure has finished.

Using these suggestions, the post ictal time and severity will be reduced considerably in many dogs.

Medications (listed by trade and generic name):
~ Phenobarbital (abbreviated pb or phb)
~ Potassium Bromide (abbreviated KBr)
~ Phenobarbital & Potassium Bromide
~ Valium (diazepam)
~ Dilantin (phenytoin)
~ Neurontin (gabapentin)

Most dogs can be controlled by using Phenobarbital or Phenobarbital and potassium bromide. Potassium bromide is used alone if the dog's liver has become damaged byPhenobarbital. (IMPORTANT: Dogs on Phenobarbital need to have their liver enzymes tested every three to four months using the following tests in a chemistry panel: ALT (SGPT); GGT; and Alkaline Phosphatase. If all three liver enzymes are severely elevated (more than just a few points above normal) then you should do a urine bile acid test or a pre- and post-meal bile acid test to see what kind of damage has been actually done to the liver. If caught very early, liver damage can be reversible.) BothPhenobarbital and potassium bromide are available by prescription in pill, capsule, and liquid form. Primadone, once commonly used, metabolizes to Phenobarbital in the liver; with prolonged treatment it can also cause liver damage. Valium, injectable administered rectally and oral tablets, are a good choice to halt a cluster seizure or interrupt status epilepticus. Dilantin is currently not recommended for use. Gabapentin is a newer drug being used for humans. It does offer exciting possibilities for dogs as it is only partially metabolized by the liver. At present it is very costly to use at around $250.00 a month; however, with the few dogs that have used it, the results have been very positive.

Diet:
Diet plays an important role in the management of Canine Epilepsy. It is very important to feed a kibble that is preservative-free. Preservatives such as ethoxyquin, BHT, and BHA should be avoided as they can cause seizures. Many "supermarket" foods are loaded with chemical dyes and preservatives. Buy a high quality kibble made from "human grade" ingredients or better yet, cook for your dog. Many recipes can be found in Dr. Pitcairn's Complete Guide to Natural Health for Dogs and Cats. PLEASE NOTE: If your dog is taking potassium bromide, be very careful when you switch dog foods. Try to make sure the sodium content is the same as the previous food. Change over very slowly, whether it is the same sodium content or different, so that the absorption rate of the potassium bromide remains constant.

SUSAN WYNN, DVM, on the canine diet: "Dogs evolved from Canis lupis - the wolf. Wolves eat caribou or the like, but if they are forced, they will eat smaller game (rarely). They have been observed to graze on grass, eat berries, etc, but only when they need to. This is our lesson in canine nutrition - they are omnivores who do well with fresh meat, the vegetation they get in a caribou stomach (which is mostly green, unless the beast is eating from baited fields), and a smattering of other stuff if they are hungry.

"Food companies have, in the main, revolutionized pet nutrition by eliminating major nutritional deficiencies and providing optimal nutrition for the average pet. Our concern, however, is not for the average pet. It is for the sick pet. If epileptic animals have a disease with even a small nutritional component, wouldn't we want to deal with it? Is your epileptic animal showing other signs of allergies? If s/he is chewing feet, scratching ears, having anal gland problems, vomiting bile seasonally, etc., one may want to consider dietary changes, including hypoallergenic diets, if appropriate.

"I think that the main benefit of feeding real food - meat (raw or cooked) raw or steamed veggies, cooked grains - is to provide stuff that is killed in the kibble extrusion process. If you or I were to eat a diet of Wheaties, yogurt, VegAll, and Spam day after day for 20 years, would this be enough? I don't know, but it makes me uncomfortable. I think our pets need a more varied diet and a fresher one than we can give them with commercial kibble. So I do recommend supplementing pet food with lean meat and vegetables."

Environment:It is important to keep your epileptic dog as free from chemical pollution as possible. Think about the environment your dog is living in. Do you use chemical sprays on your lawn? Dogs will sometimes seize only when the lawn is sprayed for weeds. How about the cleaner you use for the floor? Some dogs have been known to seize after the floor has been washed with a pine-scented cleaner. There are many things that can lower a dog's seizure threshold. Keep a diary of your dog's seizures. Note anything you have done or anything that the dog could have recently come in contact with which could have contributed to seizure. It is also a noted phenomenon that some dogs have seizures around the full moon.

Vaccinations: Vaccinations can lower a dog's seizure threshold and trigger a seizure. If you feel that this is the case for your dog, ask the vet to split the shots and give them separately. Also ask for the rabies vaccine to be given 2 weeks later. Ask your vet if he/she knows about the new three-year protocol being used now by many vets.


TREATING CANINE EPILEPSY
GOALS OF THERAPY:
The ultimate goal in treating canine epilepsy is to restore a normal life for you and your epileptic dog through complete control of seizures with no side effects. However this is frequently not possible and a more realistic goal would be to reduce the frequency and severity of the seizures without creating unacceptable side effects from the medications given. Usually even a well-controlled dog will have an occasional seizure.

Finding the right medication or combination of medications takes patience. Unfortunately what works for one epileptic dog may not work for another. Medications need to be individualized to each specific dog's needs and this often requires trial and error to find the right medication and dose.

WHEN TO START TREATMENT:
If your dog has a single seizure or infrequent seizures medication is generally not required. However, one study does suggest that dogs treated with medication early in the course of epilepsy have better long term control of their seizures, compared to dogs that are allowed to have many seizures before anti-seizure medication is started. The decision to begin medication should be made between the owner and veterinarian, taking into consideration the risks of not treating the disease against the risk of side effects of the medication.

THE CHOICE OF TREATMENTS:
Phenobarbital or Potassium Bromide is the initial treatment of choice for patients that require drug therapy. Please see the medications portion of our web site for more information on the drugs available to treat canine epilepsy.

WHY TREATMENTS FAIL:
There are many reasons why treatments can fail. The biggest ones are the owners' lack of proper administration of the medications, errors in drug therapy and improper diagnosis. Referral to a neurologist should be considered if control is not achieved within three months or if the diagnosis is uncertain.