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What Is a Seizure?
A seizure is an external manifestation (something we can see) of an intermittent massive electrical abnormality in the brain. Most dogs only have occasional seizures, yet the source or cause of the electrical abnormality is in the brain the whole time. This, of course, does not apply if the cause of the seizures is a poison or low-blood sugar, both of which are themselves intermittent events. We have a limited understanding of why the constant source only intermittently causes seizures. Unknown factors limit the activity of the source or suppress the spread of abnormal electrical activity most of the time.
A seizure is also referred to as a convulsion, a fit or an ictus. There is no such thing as a typical seizure although the most common form consists of the following symptoms: the dog stiffens, loses consciousness, urinates and salivates, jerks intermittently, paddles and then recovers. Before the seizure the dog may run to the owner or whine as if it feels uneasy or knows something is about to happen. His personality may change. Weird behavior like growling or tail chasing may occur. This is called an aura and may last a few seconds or many hours. After the seizure the dog may pace up and down or in circles, be disoriented, blind or may show behavioral changes. These are called post-ictal signs and may last from a few minutes to several days. The seizure itself usually lasts from 1-5 minutes rarely much longer. In such a case, or if one seizure rapidly follows another, the dog is said to be in "status". "Status" is an emergency situation.
Recognizing a Seizure
Depending on the parts of the brain affected by the burst of electrical activity, the signs that the dog shows during a seizure may vary. If the behavioral areas of the brain are affected, then changes in behavior may be seen. The dog may also seem to be hallucinating. Similarly is the visceral centers are involved, there will be urination, salivation, defecation or vomition. Muscle spasms, twitches and paddling are the result of motor areas of the brain being affected. Loss of consciousness, disorientation and hysteria are a result of effects on the centers controlling the alert state of the dog. It is important to understand these components of a seizure because they can each occur alone or in any combination. Thus a dog may have a seizure limited to behavioral changes, to vomiting and diarrhea or to motor twitches perhaps affecting only part of the body. Such variations may temporarily confuse both the client and the veterinarian.
What To Do When Seizures Occurs
Don't panic! Let the animal ride it out. By the time you reach an emergency medical office, the seizure will probably have passed. Moving a seizuring animal and driving in the car can be dangerous and unnecessary. Keep calm. Seizure is unsightly, but rarely harmful. Keep your hands away from an animal's mouth. Dogs and cats do not swallow their tongues as a human may. Try to cushion and confine an animal for it's safety. Talking and stroking your animal may confuse them more and they may feel they have to respond but can't. This will only add to their frustration. A quiet well-padded area is the best place to recover. The lighting should be minimal as well. Note the time and nature of the seizure on the calendar. Discuss the medical options with a veterinarian at a later time.
Causes of Seizures
Acute brain infection (encephalitis), poisoning, liver disease, increased size of the fluid-filled cavities in the brain (hydrocephalus), brain tumor, low blood sugar, low blood calcium, acute brain injury and acute infection of the outer coverings of the brain (meningitis) are all possible causes of seizures in the dog. However, the most common cause is Epilepsy. A detailed visual accounting of a seizure cannot determine its cause. This usually requires a history, examination, and testing to determine.
What Is Epilepsy?
Epilepsy is defined simply as a state of repeated intermittent seizures. It is not a single disease. It has several causes, the most common of which are post-encephalitis (acquired) and inherited (genetic). Other less common causes are shortage of oxygen (post-hypoxia) or injury at birth and brain injury (post-trauma) at any time in life. The expression "post" is used to indicate an ongoing seizure problem that persists after the acute infection or injury has occurred. Temporary problems are not referred to as epilepsy even if several seizures occur. Seizures may not even be seen at the time of the brain infection or injury. They may not start until many months later. These "causes" of epilepsy lead to the development in the brain of one or more epileptogenic foci capable of triggering seizures. These foci usually retain their ability for the life of the animal. The foci are not often identifiable as visible or microscopic changes because they are mostly functional (physiologic) lesions; i.e., the cells in them look normal but are working abnormally.
Types of Epilepsy
Types of epilepsy in man are well identified and usually dictate the choice of therapy and prognosis (forecast) that the clinician can give. This does not apply so rigidly in the dog. There is a great deal of unresolved argument about how to classify animal epilepsy. Thus, one should not even try to fit animal seizures or epilepsy into the human categories. Veterinarians recognize focal motor (twitches limited to one part of the body with no loss of consciousness), generalized motor (loss of consciousness with gross body movements) and psychomotor (marked behavioral changes seen either after the generalized motor seizures or making up the entire seizure) seizures in the dog. "Limbic," "Temporal lobe" or "Diencephalic" may also be used to describe a seizure with largely behavioral or visceral (vomition, diarrhea) changes. A few seconds before some generalized seizures a dog may twitch one leg. This is called a localizing sign and indicates which area of the brain is involved first. Veterinarians do not recognize "Petit mal" epilepsy in the dog or "Jacksonian" seizures. However, you may hear these terms applied casually to describe focal motor seizures. The term "Grand mal" is similarly used to describe generalized seizures.
Frequency of Seizures
Seizures due to causes other than epilepsy tend to follow the course of the disease. Many seizures may occur initially with an increasing frequency and severity. Then they occur less frequently and with less severity as the acute disease passes or recovery occurs. The frequency and severity of the initial seizures are an indication, but not a reliable one, of the probable cause of the seizures. Seizures due to epilepsy tend to begin as short, mild episodes that become more frequent and severe during the initial 1-2 years. After that, the pattern tends to stabilize for many years and the frequency may decrease in old age. Unfortunately this is only a tendency because epileptics may have an episode of "status" as their first seizure, have several seizures one after the other on their first day, fall immediately into a fixed very frequent pattern, show a rapidly increasing frequency or have a very varied pattern of months with no seizures followed by frequent attacks. A seizure pattern may do just about anything. The variability of seizure patterns makes evaluation of therapy difficult. The veterinarian does not know in advance what the dog's pattern will be and is usually starting treatment in the early phase when seizure patterns are developing.
Factors Affecting Frequency of Seizure
Physical irritations such as itchy skin, sore ears and pain will increase the frequency of seizures. So will emotional irritation, worry or stress such as a visit to the veterinarian or kennel, visitors, another dog, a new baby, a party, the weekend, a child leaving for college, unaccustomed boredom or any event in the life of the owner that makes the owner change habits or be upset. Dogs are sensitive to the emotions of their owners. Even events that may not seem to worry the dog can still raise the seizure frequency or precipitate seizures.
Hormones such as estrogen can have the same effect by lowering the threshold to seizures of parts of the brain. Estrogen is at high levels in bitches in heat. This is one reason that all epileptic bitches should be spayed. The other is a genetic reason.
Drugs such as phenothiazine derivatives may precipitate seizures in epileptics. Most antihistamines, tranquilizers, antemetics (anti-travel sickness) are phenothiazine derivatives. Such drugs should never be given to epileptics. Thus any veterinarian that you take your dog to must be told the dog is an epileptic.
Seizures tend to occur when a dog is in light sleep or relaxing, although some dogs may be affected while they are excited. Thus the night is a common time for seizures to occur, especially Saturday or Sunday night following the events of a weekend.
Age of Onset of Seizures
The major causes of seizures in dogs less than 1 year of age are poisons, brain infections (encephalitis) and birth defects such as hydrocephalus or liver structure abnormalities.
If the dog is over 5 years of age at the time of the initial seizure, the major causes are brain tumors and pancreatic tumors producing insulin and hence low blood sugar. However, acquired epilepsy may start at any age. Between I and 5 years of age the major cause is epilepsy (acquired or genetic). These statements only indicate tendencies and do not include several other causes of seizures.
Any breed or mongrel dog may become an epileptic for acquired reasons such as post-encephalitis, brain trauma or birth injury, but in certain breeds of dog epilepsy is a common problem. Such breeds are regarded as having a high incidence of genetic epilepsy or at least a tendency to epilepsy. The genetic basis for a "tendency" is not understood at all. Some breeds have been studied carefully and the exact genetic mechanism of epilepsy is known (Beagles, Keeshunds). In others it is generally accepted that genetic epilepsy occurs (German Shepherds, St. Bernards, all Schnauzers, Cocker Spaniels, Irish Setters, all Poodles, Tervurens). Some breeds are suspected (Retrievers, Labradors, Shetland Sheepdogs, Siberian Huskies). In some breeds the problem may be limited to just a few lines, but in others it seems widespread.
Any individual dog may have epilepsy for genetic reasons or it may have acquired it. It is rarely possible to diagnose the exact cause with certainty. The problem of genetics is the major reason that no dog that has had seizures should be used for breeding. Bitches should always be spayed to achieve better control of seizures. Male dogs also benefit from castration because of reduced sexual stress.
Diagnosis of Seizure
Cases Your veterinarian must consider all possible causes of seizures in any dog that has had even one seizure. However, the general health, age, breed and seizure pattern may suggest that some causes are more likely than others. The history, physical examination and neurologic examination all play a vital part in the diagnosis. Generally, a study of the blood cells (C.B.C. - complete blood count) and a panel of chemical analyses of the blood are done. This is to detect low blood sugar or calcium and liver or kidney disease. A blood lead analysis may be done, especially if the dog is a "chewer". In some instances a cerebro-spinal fluid (CSF) tap may be performed to measure the pressure inside the brain and to obtain fluid for analysis. An electroencephalogram (EEG) may also be obtained. Other research-type procedures may be available at Veterinary Colleges, but they usually do not specifically diagnose epilepsy. The objective of diagnosing a seizure case is to pick out all dogs with specific causes for their seizures (poisons, tumors, etc). The residual dogs are called "idiopathic" epileptics because in those individuals the exact cause of the epilepsy is only suspected.
There is no specific test for epilepsy in the dog; not even the EEG is sufficiently reliable. Epilepsy is a diagnosis of elimination - elimination of all other causes of the seizures.
Treatment of Seizures
Dogs with seizures due to diseases other than epilepsy are given specific treatments for their disease. They may also be given anti-convulsants. The owner and the veterinarian must consider when it is necessary to treat an epileptic. If seizures are mild, occur singly and less frequently than one every 2 months, the side effects of the drugs may outweigh the benefits of seizure control. If status or multiple seizures on 1 day have occurred, then the epileptic must be treated. Only 60-70% of epileptic dogs are controlled, i.e., one in three epileptic dogs has uncontrollable epilepsy. In some breeds (German Shepherd) this may drop to 25% control. Control may only be achieved after many months of therapy with a variety of drugs or drug combinations. Control may be lost even after several years of success. Control is defined as a dramatic decrease in, but not necessarily absence of, seizures. Dogs have metabolisms different from humans and their dose of any given anti-convulsant may be many times the human dose rate.
Veterinary Paractice news June 2005 Dr Jason Berg
When do you treat seizures?
There are four reasons to treat seizures.
Status epilepticus (even having one episode!).
Cluster seizures (even having one episode!).
More than one seizure a month.
Structural neurologic disease (tumors, cysts, encephalitis, strokes, other).
A typical one- to three-minute seizure has no detrimental effect on an animal.
Status and cluster seizures are life-threatening events and should be treated as such.
Common side effects with anti-convulsants are increased thirst, urination or appetite, drowsiness, clumsiness and hyperexcitability. These effects may be temporary or may persist as long as the drug is given. They are not usually serious. Some drugs produce minor liver changes. These changes may become serious in some individuals. Epileptics on medication require periodic physical examinations and blood tests.
Do Dogs Suffer in a Seizure?
Evidence suggests that the answer is no, but disorientation commonly occurs after a seizure. This may be upsetting to the dog. Some dogs may scream or moan in a seizure. This appears to be involuntary and not associated with pain.
Will the Dog's Life be Shortened?
No. Provided the epilepsy is controlled, the life expec-tancy is normal. Seizure rarely kills.
Can a Dog Ever Be Taken Off Medication?
If a dog has had no convulsions for 1 year, your veterinarian may slowly reduce the dose of anti-convulsant over several months. Some dogs eventually may be weaned off medication.