Epilepsy (Seizure)

A seizure is the clinical manifestation of an excessive discharge of hyperexcitable cerebrocortical neurons. Or, in other words, a seizure is a sudden, involuntary, time-limited alteration in behavior characterized by a change in motor activity, consciousness, sensation, or autonomic function. It is accompanied by a paroxysmal electrical cerebral dysrhythmia. Depending upon the location and extent of the seizure discharge, the clinical appearance of seizures may vary.

Seizures may occur as brief isolated events usually lasting two minutes or less, cluster seizures (two or more over a 24 hour period), or status epilepticus (sustained or serial seizures lasting at least 30 minutes). Seizures usually begin between six months of age and five years of age.

Pre-Ictal (Pre-seizure) phase

This phase may last from a few seconds to as long as 30 minutes. Some pets may not show signs of this phase at all. Some clinical signs may be anxiousness, whining or howling, seeking owner’s company or hiding, pacing, depression, or agitation.

Ictal (Seizure) phase

This is the actual seizure itself. It may last only a few seconds to a few minutes. Any seizure activity that is longer than 5 minutes is dangerous to the pet. The brain can get over heated and permanent brain damage could occur. It is extremely unusual for a seizure to last this long.

Pets may experience mild focal seizures such as facial twitching, trembling, involuntary licking, or lip smacking. Some seizures may be ‘atonic’ where the pet collapses. Most seizuring pets will have one or more of the following signs:

• Limb paddling
• Sustained or repetitive muscle contractions
• Jaw chomping and facial muscle twitching
• Salivation, urination, defecation
• Consciousness is either impaired or completely lost
• Post-Ictal (Post-seizure) phase

This phase can last from a few minutes to a few hours. Pets will exhibit periods of disorientation and confusion. The severity of clinical signs depends upon length and severity of the seizure. Some pets may be sluggish, pant, circle, have a head tilt, and even appear blind (temporarily). These symptoms are usually not permanent. Recovery can be immediate or can take up to 24 hours.

Are there any breeds predisposed to epilepsy?

Epilepsy is rare in cats. Any dog can be an epileptic. The following breeds are predisposed to this condition: Beagles, all Shepherds (German, Australian, Belgian, Tervuren), Border Collies, Boxers, Cocker Spaniels, Collies, Dachshunds, Golden Retrievers, Irish Setters, Keeshonds, Labrador Retrievers, Poodles (all sizes), St. Bernards, Shelties, Siberian Huskies, Springer Spaniels, Welsh Corgies, and Wire-haired Fox Terriers.

Causes of Seizures

• Congenital – Primary Epilepsy; Hydrocephalus (malformation of brain, contains fluid)
• Infection – Viral (Canine Distemper, Feline Infectious Peritonitis); Fungal; Protozoal (Toxoplasmosis); Bacterial
• Inflammation
• Hereditary (genetic predisposition) – Do not recommend breeding affected animals.
• Metabolic Disorders – Hypoglycemia (low blood sugar); Sepsis (systemic blood infection); Endocrine diseases; Liver disease; Hypocalcemia (low blood calcium); Kidney disease; Hypoxia (low oxygen levels)
• Toxins – Lead; insecticides; ethylene glycol; metaldehyde; strychnine
• Trauma (even from several years earlier)
• Vascular disorders
• Neoplasia (tumor)
• Idiopathic – meaning that a physical reason cannot be found for the seizures

A thorough history, physical exam and blood work performed soon after a seizure will identify or rule out most of these causes.

How neurons function

A nerve is not a continuous long filament. Instead, it is made up of many small linear bundles (neuron) with small gaps between them. When one neuron becomes excited (is activated), it releases chemicals across the nerve junction/gap. These chemicals need to reach a certain quantity before the next neuron will fire. This is called the Action Threshold Potential. Dogs and cats prone to seizuring have lower threshold potentials, allowing the neurons to fire more often and easily.

When a seizure occurs, multiple neurons are firing simultaneously in no particular order. Clinical manifestations of a seizure depend upon which neurons are firing.

Can seizures be predicted?

No. Your pet may seizure one time and then not have another seizure for 3 to 5 years; or your pet may seizure weekly or monthly. We recommend that you keep a log of when your pet seizures, time of day, severity of seizure, weather, any unusual occurences, etc.

Some pets will seizure only during times of extreme stress (such as visiting the veterinarian!), when deep asleep, eating, or other activities. Sometimes no pattern can be found at all.

What should I do when my pet seizures?

The first time that your pet seizures, we recommend a physical examination and blood work as soon after the seizure as possible. This is so that any physical problems (causes of seizuring) can be detected and treated. Sometimes further diagnostics may be recommended.

Once a physical exam and blood work have been performed, your pet does not need to see the Doctor each time that he or she seizures. However, if your pet has cluster seizuring (multiple seizures in a 24 hour period) or seizures for longer than 5 minutes, your pet needs to see a Doctor immediately.

If the seizures are periodic and mild, simply soothe your pet by gently talking to and stroking him.

Is there a treatment for epilepsy?

Multiple medications are available for treatment. Your Doctor will recommend a specific treatment based upon your individual pet’s needs. Sometimes multiple medications may be needed to control epilepsy. It takes time to get seizure medication properly regulated. Medication is usually required twice daily for control of seizures. There is no cure. Medication may sometimes become ineffective after a period of time requiring altered dosages or different medications. For a few pets, medications will sometimes not effectively control seizures.

Depending upon how frequent and severe your pet’s seizures are, treatment may not be initiated the first time that your pet has a seizure. Your Doctor will discuss the pros and cons of treating versus not treating epilepsy.

Most seizure medications act by increasing the Action Threshold Potential needed for the neurons to fire, thereby decreasing the frequency and severity of seizures. At first this tends to make the pets groggy and sedated until their body gets used to the medication. There is no medication that will completely prevent the occurrence of seizures. It usually takes 6-8 weeks for the medication to reach optimal therapeutic levels in the blood stream. Do not be alarmed if your pet should seizure again soon after beginning the medication. However, please do call your Doctor should your pet seizure again.

Pets on seizure medication will need to have their liver enzymes monitored every six months. The Doctor will also recommend that drug levels be checked the first 6-8 weeks of treatment and periodically thereafter. This is so that we can make sure that your pet is on the appropriate drug dosage. It is also very important that you let your Doctor know all other medications that your pet is taking.

What should I do when my pet is seizuring?

Remain calm and talk soothingly to your pet. Do not put your hand into your pet’s mouth. Be sure that your pet is in an environment where he will not harm himself. Remove nearby sharp objects and water. If your pet is on a piece of furniture, place him on the floor so that he cannot fall and injure himself.

Observe your pet closely and if the seizure lasts longer than five minutes, you need to take your pet to the veterinary hospital immediately.

If your pet is already on anti-seizure medication and still has seizures, call the Doctor to see if the medication dose needs to be adjusted.