SEIZURE DISORDER IN DOGS
Watching your dog experience a seizure is both frightening and disturbing, especially if it is unexpected. There is collapse, involuntary movement, and often loss of consciousness followed by a period of daze and disorientation
SEIZURE DISORDER IN DOGS
Watching your dog experience a seizure is both frightening and disturbing, especially if it is unexpected. There is collapse, involuntary movement, and often loss of consciousness followed by a period of daze and disorientation. Prolonged seizure activity constitutes an emergency. You are presumably reading this because your dog has had some kind of involuntary fit and you want to understand what it means and what can be done to prevent future episodes so let's cover some basics.
WHAT IS A SEIZURE AND HOW DO YOU KNOW IF YOUR DOG HAS HAD ONE?
A seizure results from excessive electrical activity in the cerebral cortex of the brain. The electrical activity starts in one area (called the "seizure focus") and spreads outwards through the brain causing involuntary movements and loss of normal consciousness. Classically, the patient loses consciousness, collapses, becomes stiff at first and then begins paddling or struggling but seizures can take many forms. Any involuntary behavior that occurs abnormally may represent a seizure. Seizures are classified into several categories.
GENERALIZED (GRAND MAL) SEIZURES
FOCAL SEIZURES (ALSO CALLED PARTIAL MOTOR SEIZURES)
PSYCHOMOTOR SEIZURES (ALSO CALLED COMPLEX PARTIAL SEIZURES) Psychomotor seizures are focal seizures where the seizure is more like an episode of abnormal behavior than an actual convulsion. The pet's consciousness is disturbed by this type of seizure as the pet appears to be hallucinating or in an altered state. The seizure may include episodes of rage or aggression where the pet does not recognize family members or may be as simple as a brief episode of disorientation or "spacing out." Fly-biting is an example of a psychomotor seizure.
Seizures (neurological events) are often difficult to tell from fainting spells (cardiovascular events). Classically, true seizures are preceded by an aura, or special feeling associated with a coming seizure. As animals cannot speak, we usually do not notice any changes associated with the aura. The seizure is also typically followed by a post-ictal period during which the animal appears disoriented, even blind. This period may last only a few minutes or may last several hours. Fainting animals are usually up and normal within seconds of the spell.
*** POST-ICTAL DISORIENTATION IS THE HALLMARK OF THE SEIZURE ***
CAUSES OF SEIZURES AND DIAGNOSTICS:
There are many potential causes of seizures: toxins, tumors, genetic disease such as epilepsy, infections, even scarring in the brain from past trauma. Seizures resulting from metabolic problems or toxicity (i.e. when the brain itself is normal) are called Reactive Seizures. Seizures resulting from identifiable brain abnormalities are called Structural Seizures. Seizures for which no clear cause can be found are called Primary Seizures and the patient is said to have Epilepsy.
It turns out that dogs of certain age groups tend to have common causes for their seizures. This means that certain diagnostic tests are especially important in dogs of one age group while other tests are going to be more important for dogs in another age group. Here are some basic concepts concerning how age is an important consideration:
ANIMALS LESS THAN AGE SIX MONTHS
Particularly important in small dome-headed breeds (Pomeranian, chihuahua etc.) would be congenital disease such as hydrocephalus, where abnormal fluid drainage from the brain creates damage.
ANIMALS BETWEEN AGES 6 MONTHS AND 6 YEARS
Schnauzers, Basset hounds, Collies, and Cocker spaniels have 2-3 times as much epilepsy as other breeds. Labrador retrievers and Golden retrievers are also predisposed to epilepsy but tend to begin their seizures relatively late, closer to age five.
ANIMALS MORE THAN AGE FIVE YEARS
WHEN TO BEGIN TREATMENT:
In 2016, the American College of Veterinary Internal medicine published a consensus statement on this very subject. If the dog fits into any of these criteria, medication to suppress seizures should be initiated:
It should be noted that the German Shepherd dog, Border collie, Australian shepherd, Golden retriever, Irish setter, and Saint Bernard breeds are notorious for difficulty in seizure control. It is best not to wait for frequent seizures in these cases as each seizure makes the next more difficult to control. Often medication is started in these individuals after the first seizure. The more seizures the patient experiences, the more difficult control becomes in the future.
TREATMENT CHOICES: MEDICATION
There are presently four main medications that are used in suppressing seizures in dogs in the United States: phenobarbital, potassium bromide, levetiracetam, and zonisamide. If adequate control cannot be achieved with one medication, often two or even three are combined. The ideal first line anti-convulsant medication is effective, reasonably priced, convenient to administer, and has limited side effects potential. Most dogs are started on either phenobarbital or potassium bromide but we will take a moment to review the pros and cons of all fou