Seizures are one of the most frequently seen neurologic problems in dogs. A seizure is also known as a convulsion or fit and may have all or any combination of the following signs.
- Loss of or altered consciousness
- Muscular contractions
- Involuntary urination, defecation, or salivation
- Behavioral changes including non-recognition of owner, aggression, pacing, or walking in circles
The brain is an organ that is always active but is also held in check. The slightest imbalance in excitation may cause brain cells to activate spontaneously which can cause a cascade of events leading to the uncontrollable activation of large groups of cells. Outwardly, this activation of the brain results in the clinical signs of a seizure.
Seizures can be grouped into three categories
1. They can occur in pets for no particular reason, usually showing up between the ages of 1 – 5 years. We do not know why the seizures occur and all diagnostic testing is normal. This is referred to as “idiopathic epilepsy”.
2. Seizures can occur secondary to a systemic illness such as liver disease, kidney disease or exposure to toxins. These patients are usually very sick and tend to be older than five, with the exception of toxin exposure which can show up at any age.
3. Seizures may be a sign of primary brain disease. In these cases the brain is damaged by a disease and seizures are a symptom of the underlying problem. Structural brain disease can be divided into progressive diseases such as a brain tumor or infection and static diseases like a stroke or a bleeding episode.
Seizures consist of three components or phases
- The pre-ictal phase or aura is a period of altered behavior in which the pet may hide, appear nervous, or seek out the owner. Your pet may be restless, nervous, whining, shaking or salivating. This may last a few seconds to a few hours.
- The ictal phase is the seizure itself and lasts from a few seconds to several minutes. During this period the muscles of the body may contract strongly. The pet usually falls on its side and seems paralyzed and unresponsive while shaking. Urination, defecation and salivation often occur. If it is not over within five minutes, the state is described as status epilepticus or prolonged seizure.
- During the post-ictal phase there is confusion, disorientation, salivation, pacing, restlessness, and possibly temporary blindness. There is no direct correlation between the severity of the seizure and the duration of the post-ictal phase.
How can we determine the cause for my pet’s seizure?
When you suspect that your pet has had a seizure, we recommend that the animal be evaluated as soon as possible. We begin by taking a thorough history concentrating on possible exposure to toxic substances or history of head trauma. We also perform a physical and neurologic examination.
Diagnostic tests that may be recommended or discussed include a basic battery of blood tests to check the blood sugar level and rule out disorders of the liver, kidneys, heart, and electrolytes. If cancer is a possibility, chest X-rays will be recommended to look for the presence of disease spread.
If these tests are normal and there is no exposure to poison or recent trauma, further testing, including an MRI or spinal fluid analysis, will be discussed to look for the presence of structural brain disease.
Is there a way to prevent future seizures?
Treating the underlying problem is the goal to prevent further seizures if a metabolic cause for the problem has been identified. In the case of idiopathic epilepsy or structural brain disease, we generally prescribe anticonvulsant therapy if the patient is experiencing multiple seizures or if a single seizure was severe.
We often wait to put a patient on long term anticonvulsants if only one seizure has occurred or if seizures are very mild in nature. Since starting anticonvulsant therapy means that medication must be given every 8 to 24 hours for the rest of the pet's life, we do not recommend starting these medications until the patient has multiple seizures in a day, is having frequent seizures, or if the seizures are prolonged in length (5 minutes or greater).
The veterinarian will discuss different anticonvulsant options before starting therapy with the goals of reducing the frequency and severity of seizure activity while minimizing side effects of the medications.