Seizure Disorders
A seizure is a result of sudden uncontrolled activity of brain cells. Seizures are a fairly common problem in the domestic dog, estimated to occur in approximately 1 % of the dog population. They are less commonly seen in cats.
Types of seizures
There are different types of seizures, representing different degrees of involvement of the brain. These are classified as either generalized or partial seizures. Generalized seizures involve the entire body with a loss of consciousness. Partial seizures, or focal seizures, involve only a portion of the brain and usually only a portion of the body (consciousness is often retained). By far the most common type of seizure, in both dogs and cats, is the generalized or "Grand Mal" seizure.
Stages of seizures
There are three stages of a generalized seizure. All three stages may not be seen. The first stage is the aura. In this stage the animal may appear restless, fearful, abnormally affectionate or show other behavioral changes. The second stage is the ictus stage, the actual seizure phase. Here the animal usually loses consciousness and the limbs become stiff. This is followed by paddling movements of the limbs. Crying, urination, defecation and salivation can also occur. This phase may last from a few seconds to several minutes. The final stage is called post‑ictus. Symptoms seen during this stage can include confusion, circling, blindness or sleepiness. The post‑ictus stage can last from several minutes to a few days.
Causes of seizures
Causes of seizures include epilepsy, head trauma, brain tumors, inflammation, hypoglycemia (low blood sugar), liver failure, kidney failure and poisoning.
Epilepsy is a seizure disorder of the brain for which there is no known cause. Epilepsy is the most common cause of seizures in younger dogs. Seizures caused by Epilepsy are seen in dogs between ten months and five years of age. The animals are normal between seizures with no behavioral changes or abnormalities on examination. The seizures often cluster with three or four seizures occurring over a one to two day period. They also tend to be cyclic, with the clusters recurring regularly over an interval of several weeks to several months. The length of the cycle is often constant in an individual.
Status Epilepticus is a condition of prolonged seizure activity lasting longer than 5 minutes. It may also occur as repeated short seizures without recovery between attacks. While Status Epilepticus is not common, it can result in severe brain damage and even death. Immediate veterinary care is necessary.
Diagnosis of seizures
There is no specific test to diagnose epilepsy. Ruling out other causes of seizures makes the diagnosis of epilepsy. Liver disease, kidney disease, low blood sugar and other diseases are ruled out by routine blood tests. To diagnose brain tumors and other organic brain diseases, specialized tests like a spinal fluid analysis and an MRI or CT Scan are needed. A veterinary neurologist usually does these specialized tests.
An animal’s age at the time of the first seizure, is one of the most important factors in diagnosing the cause of the seizure. If the animal is between 10 months and 5 years of age, and routine blood tests are normal, then the most likely diagnosis is epilepsy. If the animal is younger than 10 months or older than 5 years, then the cause of the seizures is unlikely to be epilepsy and more extensive testing is usually necessary.
Since epilepsy is very rare in cats, a referral to a veterinary neurologist is always recommended.
Treatment of seizures will vary with the cause. If there are organ problems (liver or kidney disease) or metabolic problems (low blood sugar), it is most important to correct the underlying problem. With infections (viruses, bacteria, fungi) the effort should be to clear the infection from the brain and decrease inflammation
Brain tumors vary in their type and location.
Some may be surgically removed and others may be better
treated with radiation. Chemotherapy may not be effective on brain tumors
because many of these chemicals are unable to enter the brain.
Seizures caused by epilepsy can usually be controlled with anti‑seizure medications. There are many anti-seizure medications available for use in human medicine Unfortunately, many of these do not work well animals. The most common drug used in veterinary medicine is Phenobarbital. It is very good at preventing seizures and has few side effects. The most common side effect is the animal being lethargic for the first two to three weeks of treatment. Once the animal adapts to the medication these symptoms usually disappear and the pet acts completely normal.
With Phenobarbital, as with other anti‑seizure medications, the amount of drug given does not always correlate with the amount reaching the blood and the brain. For this reason it is important to periodically check the level of the drug in the blood. This is done by taking a blood sample immediately before giving the medication so the concentration of drug is measured when lowest in the blood stream. This blood level shows if the amount of drug given needs to be increased, decreased or remains the same.
It is important to understand that control of seizures doesn't always mean they stop completely. The goal of therapy is to reduce the frequency and intensity of the seizures to a level acceptable to both the pet and owner. For instance, if seizures can be reduced from one per month to one every six or seven months, this may be the best control possible.
Link to more info at the canine epilepsy website.
