A typical picture of a seizure usually brings to mind a Grand-Mal. Absence seizures are more subtle and described as “blanking out”, “staring” or having “lapses of awareness”. Pronounced (ab-Sawntz) also called Petit-Mal. To an onlooker, it would appear as if the person is daydreaming.
It was Louis-Florentin Calmeil (1798 – 1895), who coined the term “absence”. He introduced the concept of epileptic absence for the brief loss of consciousness or confusion seen in epileptic patients.
This article looks at canines and humans in regard to absence seizures. The prevalence of epilepsy in the general dog population has been estimated at .5 to 5.7%. My canine, a Belgian Tervuren has seizures. By analyzing and studying the comparisons between humans and canines it helps to understand, identify and even prevent onset, as the research on canine seizure disorder is limited.
LENGTH OF ABSENCE SEIZURES
In both human and canine cases, absence seizures start and end suddenly.
Described as spells, absence seizures can last less than 10 seconds to as long as 20 seconds. A person might appear to be daydreaming and blink repetitively. When completed, normal function will continue, as if nothing happened. Complex absence seizures are more than 10 seconds.
Episodes for a dog might be similar, eyes open while lying down, staring, a fluttering of the eye going on for several seconds. The dog will appear to be checked out, be in a deep state, as if in a sudden brief loss of consciousness. Absence seizures are rare in animals.
My dog is diagnosed with idiopathic epilepsy. Absence seizures occur in both idiopathic generalized epilepsy, and in the case of children, juvenile myoclonic epilepsy (quick little jerks of the arms, shoulder, or occasionally the legs and usually occurring in the early morning).
In the case of animals, “Several animal models demonstrate the genetic basis for absence seizures” from a study of rats and mice according to Medscape and Scott Segan, MD. My own dog exhibits the quick jerks of shoulder and legs and it is always usually in the early morning hours.
SYMPTOMS
Absence seizures are more common in females. However, absence epilepsy with myoclonus (brief muscle twitches) has a male predominance. According to the National Institute of Neurological Disorders and Stroke, myoclonus describes a symptom and generally is not a diagnosis of a disease. Myoclonic twitches or jerks usually are caused by sudden muscle contractions, called positive myoclonus, or by muscle relaxation, called negative myoclonus. They can occur alone or in a sequence, with or without a pattern. The twitching cannot be controlled in humans or animals.
An untrained eye would see the seizure as just staring. What you would see is a change in muscle activity and most commonly, eye blinks. The mouth would appear to make tasting motions, hands might move and fingers rub together or there could be a relaxation of the muscles.
In people these types of seizures usually begin in childhood between ages four and 14. The children usually have normal development and intelligence. In people 70% of absence seizure cases stop by age 18. Children who develop absence seizures before age 9 are more likely to outgrow them than children whose start after age 10. Children with absence seizures do have higher rates of behavioral, educational and social problems. This is also true in dogs. In canines most seizures occur when they are relaxing or sleeping, negative myoclonus, and are defined as genetic, if they occur prior to 5-years-old.
COMPARING ABSENCE SEIZURES to DAYDREAMING
Daydreaming doesn’t occur with the frequency of an absence seizure.. It occurs when a child is bored, doesn’t begin abruptly, can be interrupted, and lasts until something interesting occurs. The child would just stare and is alert immediately afterwards.
In comparison, an absence seizure could occur 50 to 100 times per day and can occur during physical activity often with hyperventilation (deep or rapid breathing). They begin abruptly and cannot be interrupted. They last rarely more than 15 to 20 seconds and like daydreaming the person just stares and is alert immediately afterwards. Absence seizures have no aura. An aura is usually the feeling or first sign a seizure is going to occur and can happen several seconds up to 60 minutes before a seizure. Absence seizures can effect learning in children due to lapses causing an inability to concentrate.
HOW IS DIAGNOSIS MADE?
Usually an EEG (electrocardiogram) which records brain waves is helpful in diagnosing absence seizures in people. The child would be told to breath rapidly, which will often produce a seizure. Images are taken of the brain, but basically little is known about the “cause. EEG testing is necessary to help make medicating decisions.
Absence seizures create unique EEG patterns. Due to the fact that absence seizures have consciousness without convulsions, it is currently uncertain due to lack of specific research, if they appear in dogs or not.
TREATMENTS
Ethosuximide (Zarontin) is used as the medication of choice in treatment of absence seizures in people. Other effective medications treat a wider base seizure activity such as Valproic acid (Depakene, Depacon) and divalproex sodium (Depakote, Depakote ER). Only Ethosuximide and Valproic acid have FDA approval for absence seizures.
Medicating decisions with children need to be made carefully. Anti-epileptic medication is relatively toxic and can have sedative and cognitive side effects. Children with absence seizures need to be on medication for many years, and in some for life. Something to consider is that absence seizures may not be helped by anti-epileptic medications.
Now that said, the Epilepsy Foundation says “Although manifestations of their seizures are usually subtle, children with absence seizures need prompt and effective treatment because their seizures can interfere with learning.”
Canine treatment is usually Potassium Bromide (kBr), Phenobarbitol (PB), or a combination of both. Also, Diazepam (valium), if needed. New medications, such as Zonisamide and Keppra are available. My Belgian Tervuren is on Potassium Bromide at a level of 3 mls, in a 296 mg compound and amino acid, Taurine. He is hypothyroid and takes 4 L-Thyroxin tablets at .2 mg each.
Treatment usually involves anti-epileptic drugs once proper diagnosis is obtained. Treatment goal for humans or canines is to suppress all epelepticform activity.
Along with medication, a Ketogenic or medium-chain triglyceride diet might be recommended as a part of treatment.
The Epilepsy Foundation describes the KETOGENIC DIET as a very high in fat and low in carbohydrate diet. It was first developed 80 years ago. It is used with those who have epilepsy because it makes the body burn fat for energy instead of glucose. The diet has helped two out of three children and may prevent seizures completely in one out of three. It is a serious form of treatment and has some side effects. Research is ongoing as to the diet’s underlying positive effects.
In canines, a ketogenic diet would make perfect sense and take the form of raw meats or cooked meats in appropriate nutritionally sound increments.
MEDIUM-CHAIN TRIGLYCERIDE DIET
The MCT diet, according to Epilepsy.com, is most often used in England and Canada. It refers to the type of oil (medium chain triglyceride) designed to make the diet more palatable, similar to a modified Atkins diet and low glycemic index treatment.
HUMAN vs. CANINE
According to Canine Epilepsy Network it is not certain absence seizures (Petit-Mal seizures) actually occur in pets. Most of the seizures occuring in dogs are called focal seizures. Definition of a focal seizure, called a minor motor seizure, originates in the area of the brain that controls movement. For example, the front limb may then begin to twitch and buckle.
During a simple focal seizure, the pet is usually alert and aware and may attempt to seek out owner, confused about what is happening. The seizure may stop there or it may generalize to a classic Grand-Mal seizure.
Over thirty purebreds are prone to seizures, as well as mixed breeds. A discontinued report by the American Begian Tervuren Club (ABTC) with John Oliver, Jr., DVM, 1983, found that out of 268 Tervuren studied 21% or 57 had suffered more than one seizure. The authors then concluded, “At this time, we believe there is sufficient evidence for the probable genetic basis of seizures in Tervuren to warrant concern on the part of breeders.” Today the ABTC states “Ideopathic Epilepsy is one of the genetic problems that plagues the well-being of the Belgian Tervuren.” A buccal swab test kit is available in a study of epilepsy in Belgian Tervurens and Belgian Sheepdogs from the Canine Genetic Analysis Project.
In humans, an epileptic seizure is a definable event that can be classified according to categories set by the International League Against Epilepsy. A formal classification system specifically for dogs and cats does not exist, but seizures can nevertheless be classified as either partial or generalized episodes.
Online Resources:
Epilepsy Foundation
National Institute of Neurological Disorders and Stroke
Epilepsy.com
Medscape, Scott Segan, M.D.
Canine Epilepsy Network
American Belgian Tervuren Club on Ideopathic Epilepsy
