Canine Epilepsy: Seizures in Dogs

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Epilepsy is a brain disorder that causes recurrent seizures. It is relatively common in dogs. Signs of epilepsy generally show up between the ages of 6 months and 5 years, with the most typical age of onset being 2-3 years. Epilepsy in dogs is not curable, but it can usually be managed with medications so that seizures are kept to a minimum and quality of life is good.

Causes of Seizures in Dogs

Seizures are a sign of abnormal electrical activity in the brain. There are many causes of seizures in dogs other than epilepsy. In fact, epilepsy is only diagnosed when other causes of seizures can be mostly ruled out.

Causes of seizures in dogs include:

• Congenital brain defects
• Brain tumors
• Brain injury such as head trauma or stroke
• Infection
• Abnormally low or high blood sugar
• Heatstroke or high fever
• Kidney disorders
• Liver disorders
• Low thyroid level
• Toxins
• Medication side effects
• Epilepsy

Types of Seizures in Dogs

There are three main types of seizure activity that occur in dogs: grand mal, partial, and complex. Characterizing the type of seizure that is occurring in a dog can help a veterinarian narrow down the cause.

• Grand mal seizures are dramatic and hard to miss. A dog will typically lose consciousness, fall down on one side, and have uncontrollable muscle movements of the whole body, usually resulting in a kicking or paddling motion. The dog may salivate profusely and sometimes urinate or defecate involuntarily. Epileptics most commonly have grand mal seizures.
• Partial seizures, as the name implies, only affect part of the body. The dog does not usually fall down or lose consciousness, but he may seem to be in a trance. There are odd repetitive movements such as facial twitching, jaw chattering, or pawing and biting at a body part.
• Complex seizures cause bizarre behaviors in dogs such as howling, fly-biting, circling, or sudden unprovoked aggression. Also called psychomotor seizures, these can be the hardest to diagnose as seizure activity because the signs can overlap with common canine behavioral disorders.

Partial and complex seizures are more likely to be associated with focal brain disease (e.g. trauma, stroke, infection, or tumor) than are grand mal seizures.

Stages of a Seizure

Seizures, regardless of type, are often preceded by an "aura," or a telltale sensation associated with a coming seizure. Humans describe this phenomenon as a peculiar sensory experience: a feeling, smell, taste, or sight that indicates that a seizure is coming.

Dogs can't verbalize such sensations, but they may act restless, disoriented, aloof, or clingy right before a seizure starts. This stage of a seizure is known as the pre-ictal period.

The seizure itself, however it manifests in that particular dog, is the ictal period.

Seizures are followed by a post-ictal period in which the dog is no longer twitching but also isn't acting 100% normal yet. He may appear confused, agitated, uncoordinated, or unable to see.

A typical seizure (the ictal phase) lasts for 1-2 minutes, although it can seem much longer to the worried observer. See the box below for how to help a seizing dog.

A single seizure is usually not harmful. One exception is when seizures last longer than 5 minutes (a condition called status epilepticus) or come in rapid succession with little pause in between (this is known as cluster seizing).

A dog in status epilepticus or that is experiencing cluster seizures can dangerously overheat due to repetitive muscle movement. If your dog has been seizing continuously for 5 minutes or more, seek emergency veterinary care immediately.

Causes of Epilepsy in Dogs

The underlying cause of epilepsy in dogs is not well understood. It seems to have a heritable component, and certain breeds are thought to be more susceptible to it. These breeds include schnauzers, beagles, basset hounds, collies and cocker spaniels.

Diagnosis of Canine Epilepsy

Epilepsy is diagnosed when all other causes of seizures are excluded. Your veterinarian will ask several questions to determine if the event truly was a seizure. A video recording of the seizure, if available, is invaluable at this time. A thorough history can help the veterinarian to pinpoint any possible inciting causes such as an injury or toxic exposure.

The doctor will then do a full physical and neurological examination. Workup for a seizing dog typically includes a complete blood count and chemistry analysis, thyroid levels, urinalysis, and possibly x-rays.

Depending on the results of the history and initial workup, a complete workup may include a referral to a canine neurologist for advanced imaging (CT scan or MRI) and spinal fluid analysis. That said, most general practice vets feel comfortable diagnosing epilepsy without advanced tests when the presentation is classic (a young, otherwise healthy dog having grand mal seizures) and basic tests are normal.

Treatment of Epilepsy in Dogs

Treatment for epilepsy is rarely indicated after just one seizure. After running tests to rule out other causes, your veterinarian will most likely recommend watchful waiting. The following criteria usually indicate that treatment is necessary:

• Seizures are particularly severe.
• Seizures are increasing in frequency and are now occurring more than once a month.
• Seizures occur in clusters.
• The patient is from a seizure-prone breed.

Treatment for epilepsy is never curative and must be continued lifelong. The goal of treatment is to reduce the severity and frequency of the dog's seizures.

A variety of anticonvulsant drugs are available to treat canine epilepsy. Phenobarbital and potassium bromide are two common choices. Side effects of both medications can include increased appetite and thirst, stomach upset, and sedation, but the sedation usually wears off after several weeks. Blood levels must be regularly monitored and dosages adjusted to be sure the medication is working properly. Maintaining a seizure log is crucial for guiding your dog's therapy. When one drug no longer controls seizures, one or two additional drugs may be added.

Newer anticonvulsants borrowed from human medicine are gaining popularity for use in dogs because of their improved safety and efficacy and reduced side effects; however, the cost can be much higher. Examples include levetiracetam (Keppra®), zonisamide, and gabapentin.

Note: Never give your dog a human medication that has not been specifically prescribed by your veterinarian.

The newer anticonvulsants can be used as add-on drugs when seizures become refractory, or they may be prescribed from the outset. Every dog reacts differently, and determining the proper treatment can require time and patience. Your veterinarian will help determine the best medication or combination of medications for your epileptic dog based on his age, other medical conditions, and other factors.

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