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Epilepsy
Introduction
Epilepsy is a condition that can affect any breed of dog. It's is defined as a neurological disorder characterized by sudden, recurring attacks of muscular, sensory, or psychic malfunction with or without loss of consciousness or convulsive seizures.There is a higher incidence in pure breed dogs of any size than in mixed breed dogs, and is therefore likely to be inherited.
Poodle
What is epilepsy
Epilepsy is a functional abnormality in a neuron that causes an abnormal neurologic excitation that generalizes to the whole brain. It is similar to a lightning strike on a house that sends abnormal current through the normal electrical system.
Types of Epilepsy
Primary epilepsy: also known as idiopathic, genetic, inherited, or true epilepsy. There are no positive diagnostic findings that will substantiate the diagnosis. It is a case of ruling out every other possibility. The first seizure in a dog with primary epilepsy usually occurs between the ages of 6 months and 5 years. (Oliver, Seizures). However, a diagnosis of primary epilepsy is not proof of a genetic defect; only careful breeding studies could prove that. The breed, the age, and the history may suggest a genetic basis for primary epilepsy if there is a familial history of seizures.
Secondary epilepsy refers to seizures for which a cause can be determined, and there are many. In dogs less than one year of age, the most commonly-found causes of seizures can be broken down into the following classes: degenerative (storage diseases); developmental (hydrocephalus); toxic (lead, arsenic, organophosphates, chlorinated hydrocarbons, strychnine, tetanus); infectious (distemper, encephalitis, and others); metabolic (such as transient hypoglycemia, enzyme deficiency, liver or kidney failure); nutritional (thiamine, parasitism); and traumatic (acute injury).
In dogs 1-3 years of age, a genetic factor is most highly suspected. In dogs 4 years of age and older, seizures are commonly found in the metabolic (hypoglycemia, cardiovascular arrhythmia, hypocalcemia, cirrhosis) and neoplastic (brain tumor) classes. Seizures are also associated with hypothyroidism, which is a familial (inherited) autoimmune disease of purebred dogs.
Signs
The main sign of epilepsy is seizures, which can be categorized in three ways. Intracranial causes of seizures have detectable defects, such as a tumor, inside the brain. Extracranial causes of seizures have metabolic or toxic changes that are outside the brain but affect the
brain to cause a seizure. Seizures of unknown cause form the third category, called idiopathic epilepsy.
Seizures in a dog less than one year of age are likely to be caused by congenital/genetic problems, infections, or toxins. A dog greater than six years old is likely to have tumors or infectious/inflammatory problems that are causing the seizures. Dogs between 1 and 5 years of age that are normal between seizure episodes are most likely to have idiopathic epilepsy. A seizure refers to the involuntary contraction of muscles. Seizures can result from abnormal electrical activity in the brain brought on by tumors, blood clots or scar tissue, or from chemical imbalances such as low blood sugar or nerve stimulating drugs. Tetanus toxin poisoning can stimulate muscles to contract resulting in a seizure. A seizure may involve all the skeletal muscles or be localized to spasms in a single bundle of muscles.
Recognizing a seizure is important and often difficult. A seizure can be minor and show as only slight loss of muscle control (called a partial motor seizure), or it can be severe, with the dog paddling on the ground completely out of control (called a grand mal seizure). In general, a dog will lose bladder and bowel control during a seizure, will be unaware of its surroundings, and will appear abnormal after a seizure.
Types of seizures
• A grand mal seizure refers to severe, widespread cramping of the body’s skeletal muscles. Skeletal muscles in general are those that attach to bones and allow for body movement; there are special smooth muscles that don’t attach to bone that usually are unaffected during a seizure. These smooth muscles reside mainly in the intestinal tract, blood vessels and specialized organ tissues. The heart muscle is actually different from either skeletal muscle or smooth muscle. Grand mal seizures are rather shocking to see.
• A petit mal seizure, see the short movie below, is a less severe form of seizure where the patient still has some voluntary control of movement and coordination but where certain muscle groups are “doing their own thing” and brain electrical activity is mildly disrupted. Staggering, momentary “staring into space” and other forms of incoordination may be visible to an observer.
• Convulsion usually refers to a grand mal seizure. Sometimes these terms are loosely applied to an epileptic episode. We might say a patient is having an “epileptic attack”, or “is having a seizure” or maybe even a “fit”. However we describe it, the occasion will be uncomfortable for the observer and the victim.
• Status epilepticus refers to a very dangerous situation where a rapid successions of grand mal seizures occur without periods of rest or muscle relaxation between epileptic episodes. Status epilepticus requires prompt medical intervention.
Treatment
Treatment for epilepsy does not cure dogs of the disease. Instead, the goal is to control the seizures. Left untreated, this disease and its signs will continue to
worsen.
The first line of treatment for epilepsy is a barbiturate, usually phenobarbital. This drug has anti-seizuring effects and can be used to treat dogs over the long term. The general goal of therapy is either to reduce the number of seizures by half or to double the time between seizures. This goal does depend somewhat on the individual case. In some cases Valium may be used when Phenobarbital cannot be utilized or when a combination of medications are prescribed.
Diazepam (Valium) is also used for treatment of status epilepticus.
The second-line drug that is used in the treatment of epilepsy is potassium bromide. This drug does not have FDA approval and is available to treat seizures in dogs by special license only.
Any dog receiving anti-epileptic medication should have periodic blood samples evaluated for blood chemistry balance. Since many medications are degraded and eliminated from the body via the liver, an assessment of liver function is a priority.
Why Treatment Fails
There are many reasons why medical treatments can fail.
The biggest reason is the owner's lack of proper administration of the prescribed drug. The progression of an underlying disease (such as brain tumor) may resist treatment. Also, gastrointestinal disorders can affect drug absorption, and tranquilizers may stimulate seizures. Drug interactions can occur and adversely affect the level of anticonvulsant drug in the dog's system. And it just might be that a particular drug may not work for that animal.
What to do during a seizure? If you happen to witness a seizure, there is not much you can do at home to get it under control. Try to remove any objects from the immediate area that the dog may bump in to and injure itself. Do not try to open the dog’s mouth to pull the tongue out. Although it can happen, it is extremely rare for the dog to “swallow the tongue” and obstruct the airway. Plus the strength of the dog’s jaws will probably prohibit any attempts you make to open the mouth to inspect the area.
• It is important to note that an epileptic dog can live a normal life with proper treatment but usually will not live quite as long as a normal dog. If you would like further information, contact your veterinarian.
