A seizure is a series of uncontrolled muscle spasms. It is triggered by a defect in the brain, which in turn is caused by an array of disorders both in the brain and the body. In some patients, seizure activity can be eliminated by correcting the underlying problem. In others, owners must make a lifelong commitment to their canine friends to keep seizures to a minimum with daily medication.

In a healthy brain filled with millions of neurons (brain cells), electrical impulses are generated and precisely organized, allowing not only thought, but also initiation of events in the body, including muscle contractions.

When neurons are not active, they should be in a state of rest. Some, however, become spontaneously excited, without any outward stimulation. The number of neurons that become excited is typically small enough to be kept in balance by those at rest. However, if too many neurons are excited at one time, a flood of electrical current flashes through the brain triggering a seizure, which is visible as uncontrolled muscle contractions.

Seizures tend to follow a predictable cascade of events. The dog gets a glazed-over look in his eyes and his body stiffens. He may fall to one side, typically with all four legs rigid, and then pull his head back as his neck muscles spasm. Sometimes his legs thrash violently and he may involuntarily urinate and defecate.

The period of muscle contractions, called the ictal phase, usually lasts for only 10 to 20 seconds but because this episode is so intense, it seems longer to a helpless observer. The pre-ictal phase, which occurs before seizure activity, is a period of disorientation or behaviour change that lasts for a few minutes to an hour. The post-ictal phase (after the seizure) is signaled by weakness, blindness, ataxia, and stupor. It can take up to 24 hours for dogs to recover fully from a seizure, though most dogs look normal within an hour.

Dogs can exhibit all kinds of seizure activity. Sometimes they are as powerful as those described above. Sometimes dogs just get disoriented and stiff. A few dogs experience “visual” seizures – they act like they see imaginary flies buzzing around the room.

The following video has been prepared to show dog owners the immediate steps to be taken if their dog starts to seizure.

A dog that seizures repeatedly, one immediately after another, needs prompt treatment. Uncontrolled continuous muscle activity (status epilepticus) can raise a dog’s body temperature to a level that can permanently harm the brain.

Seizures that occur intermittently may or may not need to be treated, but the cause does need to be investigated. Do they originate from an imbalance in the body, or are they induced by a primary brain disorder?

A dog with uncontrolled or overcontrolled diabetes mellitus can seizure because his brain cells do not get enough sugar. Toxins in the blood (seen with liver and kidney disease), a lack of oxygen due to anemia (seen with immune-mediated hemolytic anemia or ingestion of onions), as well as drugs and insecticides, can all trigger seizures. Imbalances of hormones (hypothyroidism) and electrolytes (Addison’s disease) have also been linked to seizure activity.

All of these disorders of the body are diagnosed with blood and urine tests. If a disease is identified, rectifying that problem usually resolves the seizures.

If the body of a seizuring dog is healthy, the primary problem (by default) is in his brain. A young dog can have a developmental disorder called hydrocephalus, commonly known as water on the brain. Older dogs may have brain tumours. Typically, cancer in the brain originates from other areas of the body. For example, mammary cancer can spread via the blood to the brain.

Meningitis, which is induced by fungal agents (e.g. cryptococcus) or bacteria can trigger seizures. The same occurs with inflammation in brain tissue caused by an overactive immune system (e.g. Pug encephalitis). These diseases can be difficult, or perhaps impossible, to treat. Doing an MRI or CSF tap can help diagnose these disorders in the brain.

After a veterinarian has ruled out all diseases of the brain and the body as causes of seizure activity, she labels the seizuring patient as an epileptic. Epilepsy appears to have a genetic basis in some individuals. It can be serious enough that it requires treatment.

The medications used to manage canine seizures vary with the situation and the goal of therapy. If an owner is at home and her dog has a single seizure, there is usually no need to intervene. The dog just needs a quiet environment to recover from the post-ictal phase. If a dog is in status epilepticus, he needs emergency treatment in a veterinary hospital. Intravenous Valium (or another sedative/anesthetic) is needed to halt seizure activity.

In cases where dogs have only intermittent, but clustered seizures, some veterinarians send home “Valium kits” with their clients. The owner gives the Valium after the first seizure to help stop more from occurring. Valium can be given easily at home by squirting it in the rectum. It is absorbed rapidly through the rectal wall into the bloodstream.

When a dog is seizuring more often than once every four to six weeks, or if he has severe cluster seizures, daily anti-convulsant therapy is warranted. The decision to use these medications must be made carefully. An owner must be able to reliably give the drugs twice daily. If they are not given on schedule, the dog could go through withdrawal, which might prompt more seizure activity.

Anti-convulsant medications help raise “seizure threshold”. They change brain chemistry so that it’s less likely that aberrant excited neurons will stimulate a seizure. Several medications are used, and in many cases, they are used together so that lower doses of each drug can be given and minimize drug toxicity.

Most dogs can be stabilized on anti-convulsant medication, however, their caregivers must be able to deal with the expenses associated with treatment and monitoring. More importantly, they must make a commitment to give the medication for the duration of their canine friends’ lives.

Dr. Louise Janes D.V.M. & Dr. Jeff Grognet D.V.M.
Mid-Isle Veterinary Hospital
5-161 Fern Road West
Qualicum Beach, BC
Tel (250) 752-8969

See all articles by Dr. Louise Janes D.V.M. & Dr. Jeff Grognet D.V.M.