Seizures and Idiopathic Epilepsy

General Overview:

Seizures are the most frequently reported neurological condition in dogs. A seizure is defined as a transient convulsion or fit that is due to abnormally excessive neuron activity in the brain. Epilepsy refers to at least two seizures more than 24 hours apart. With epilepsy, seizures can be single or may occur in clusters, and they can be infrequent and unpredictable, or they may occur at regular intervals.

Seizures occur when nerve cells in the brain become hyper-excited and send rapid-fire messages to the body. If nerve cells in an isolated part of the brain are affected, only part of a dog’s body is affected, resulting in a focal (partial) seizure. Focal seizures are exhibited by localized body movements, such as head bobbing, unusual movement in one limb or one side of the body, or imaginary fly biting without a change in consciousness. If circuits throughout the entire brain misfire, the dog has a generalized seizure, which is referred to as a grand mal or tonic (stiffening)-clonic (paddling) seizure. These seizures involve teeth gnashing, frantic thrashing of the limbs, excessive drooling and loss of bodily function resulting in uncontrolled urination and/or defecation. The severity of seizures will most likely worsen over time due to a kindling effect where the threshold for seizures will lower as the number of seizures increase.

Cluster seizures occur when a dog has many seizures in a short period of time. Status epilepticus is a prolonged seizure that lasts more than five minutes. These last two types are medical emergencies and require immediate management by a veterinarian.

Idiopathic Epilepsy (IE) means frequent seizures of an unknown cause. This is the most common type of epilepsy and is an inheritable disorder, but the genetic markers for epilepsy remain elusive. It is a complex genetic disorder and the mode of inheritance still has yet to be identified in humans, as well as canines. Other causes of epilepsy include liver disease, kidney failure, brain tumors or trauma, toxins, hypoglycemia, hyperglycemia and electrolyte imbalances. Seizures often occur at times of changing brain activity, such as during excitement or feeding, or as the dog is falling asleep or waking up.

IE is present in all GSMD lines. It typically surfaces between the ages of 1 to 3 years, but it can become evident as early as 6 months and as late as 6 years.

Warning Signs and Symptoms:

The pre-ictal (aura) phase: This is the period that precedes the actual seizure and is a time of altered behavior in which the dog may appear nervous with a wild eyed look and seek out the owner. The dog may hide, shake, whine, salivate excessively or just be restless. This also may not occur in your dog.
The ictal phase: This can last from a few seconds to several minutes and will vary in appearance depending on what type of seizure (see above) your dog is experiencing. The ictal phase can range from focal seizures to full-blown grand mal seizures and loss of consciousness. Focal seizures will be localized and can be mild whereas grand mal seizures will usually start with the dog falling over to his side, paddling his legs, arching back, frothing at the mouth, chomping teeth and losing consciousness. Seizures are not painful to the dog and they do not swallow their tongues.
The post-ictal phase: This is the period immediately after a seizure. Often the dog will exhibit confusion, disorientation, pacing or running aimlessly, restlessness, temporary blindness and salivation. There is no direct correlation between the severity of the seizure and the duration of the post–ictal phase. It can last just a few minutes or hours until complete recovery.

What to do during a seizure:

Remain calm and talk softly to your dog. Getting anxious will not help your dog. Keep the dog safe by moving away from harmful objects or locations (stairs). Remove other pets and children from the immediate vicinity. Other pets may attack a seizing dog.
Do not restrain or hug the dog. Avoid touching their head and do not put your hands or anything else in their mouth. Unlike humans, dogs cannot choke on their tongues. Dogs can inadvertently bite while they are having a seizure. Rescue medications can be given if prescribed by your veterinarian.
Track seizure duration and presentation. Keep the dog cool. Seizures that last more than 2 minutes can put the dog at risk for overheating. You can cool the dog by applying cold wet towels or ice packs (frozen veggies work too) to back area, neck, groin and paws. Enter time, date, duration and all details of seizure into a journal.
After seizure, keep talking calmly to dog. Approach with care until they are fully aware. Have a slip lead ready to walk the dog or to restrain him. Feed the dog high caloric items such as ice cream, honey, corn or karo syrup to help restore blood sugar levels.
Contact your veterinarian or emergency veterinarian promptly if it’s a first time seizure, a seizure lasting longer than 3-5 minutes, multiple seizures in a row without becoming conscious, or if your dog has 2 or more seizures occurring in a 24-hour period. Notify your dog’s breeder.

What to Expect at the Vet:

After a seizure, your veterinarian will begin by taking a thorough history, concentrating on possible exposures to poisonous substances, or a history of head trauma. Your journal times, dates, lengths of seizures, along with where your dog had been before its seizure, will be a valuable tool for your veterinarian. The vet will also perform a physical examination, urinalysis, CBC, and possibly an ECG or electrocardiogram. This will help rule out disorders of the liver, kidneys, heart, electrolytes and blood sugar levels. Idiopathic epilepsy is diagnosed by ruling out other acquired diseases that can also manifest seizures. If these tests are normal and there is no exposure to poison or recent trauma, further diagnostics like an MRI may be recommended, depending on the severity and frequency of the seizures.

Treatment/Prevention:

The decision to start antiepileptic drug treatment is based on a number of factors, including the cause of seizures, risk of recurrence, seizure type and side effects of the medications. In dogs, especially Swissys, long-term seizure management is most successful if therapy is initiated early and aggressively after onset of seizures. If possible, one should consult with a veterinary neurologist as soon as possible.

Although a variety of drugs are used for management of epileptic dogs, there are no real guidelines regarding the choice of a first-line drug for long-term management of seizures in dogs. Phenobarbital and potassium bromide have been used as first choice sole drugs for long term management of epilepsy in dogs based on their long standing history, widespread availability and low cost. During the past 20 years, many newer anti-epileptic drugs with fewer side effects have been developed and are safe for use in our canine patients. These include levetiracetam, zonisamide, gabapentin, pregabalin and others.

After initiation of a therapy, it is important to systematically monitor seizure control, the systemic effects of the drug, and the drug concentration in the blood. The focus of monitoring treatment is to optimize seizure control while minimizing adverse effects. This depends on accurate owner observation (a detailed journal) and good communication with your veterinarian. This often will take some trial and error to find the best mix or “cocktail” of medications for your dog, so patience and diligence is key while adjustments in your dog’s regimen are made to give him the best outcome possible.

Resources:
Canine Idiopathic Epilepsy, Veterinary Health Center, University of Missouri
Seizures in Dogs by Earnest Ward DVM, updated by Rania Gollakner, BS DVM
Seizures in Dogs: Causes, Symptoms & What To Do- Pet MD
Epilepsy Handout-GSMDCA Health Committee
Article by Brigitte Rhinehart for GSMDCA