Terry Animal Hospital
3 Washington Street
Rockville Centre, NY 11570
(516) 764 – 2880
Drs. Perrier, Foy, Ng, & Funk www.TerryAnimalHospital.com
What is a Seizure?
A seizure is caused by an outburst of abnormal electrical activity ( like an “electrical storm”
) that disturbs normal brain function. A seizure has a sudden onset, ceases spontaneously, & has a tendency to recur. Seizures are the most common neurologic disorder seen in small animal practice. There are several types of seizures depending on what part of the brain is affected & how the abnormal electrical activity was initiated.
Types of Seizures
Any involuntary abnormal behavior may represent a seizure. While some seizures occur after exercise or emotional arousal, most seizures ( especially in dogs ) occur when the pet is relaxed, sleeping, or early in the morning. There are 3 main types of seizures:
Generalized ( Grand Mal ) seizures
This is the most common form of seizures in small animals, involving most of the brain. Usually, the pet will fall to their side with legs stretched out & the head tilted back. They may or may not vocalize—this is involuntary & does not indicate any pain.
The entire body is usually stiff or undergoes cycles of stiffness…then muscular contractions ( tonic/clonic action ).
Although the eyes remain open, the animal loses consciousness & may drool, urinate, defecate, &/or express the anal glands (foul odor). The stiff phase ( tonic ) usually lasts no more than 30 seconds & gives way to clonic , rhythmic movements (paddling, facial twitching, &/or jaw chomping). Sometimes a pet may not breathe during a seizure & the tongue will turn purple or blue.
Following a seizure the pet may lay motionless for a period of time but eventually gets up. A pet may bounce back & appear perfectly “normal” or more typically, have a post-ictal phase after the seizure. A pet may be transiently blind, disoriented, &/or unsteady on his feet. You may notice him pacing or running around the house. He may appear startled after bumping into things unexpectedly. It is very common for pets to be very tired &/or very thirsty after a seizure.
December 2011

Not all criteria need to be met so discuss what you saw with your veterinarian. It may feel like eternity, but the average seizure lasts no more than 2 minutes. If a seizure continues much longer, we are concerned your pet may be having another seizure on top of the first seizure—this requires immediate veterinary care.
Partial seizures
This form of seizure originates from a specific area of the brain & is reflected by activity of a specific region (or side) of the face. The body may or may not be involved as well. Pets usually remain conscious during this seizure . They may seek the owner or appear confused about what is happening. The abnormal brain activity characteristic of a partial seizure may “spread” & become a generalized seizure. Most partial seizures involve abnormal muscle movements (much like generalized seizures) however, some partial seizures affect a pet’s behavior.
Psychomotor seizures
These seizures involve a disturbance of the pet’s sensorium which is expressed as a behavioral abnormality. It typically involves some sort of senseless repetitive action.
Some examples include, but are not limited to, staring into space, maniacal running, tail chasing, flank attacking, fly or light biting, abnormal aggression or rage, & brief episodes of unconsciousness. These may also evolve into generalized seizures.
What Causes Seizures?
Seizures can be subdivided into 3 major categories.
Structural causes
These causes originate within the skull . The common structural causes of seizures depend highly on the age & breed of the pet. While there are many structural conditions that cause seizures, tumors represent the largest portion in older animals. The following are a few common causes of seizures induced by structural abnormalities.
Malformation ( hydrocephalus )
Injury ( hit by car, trauma at birth )
Neoplasia ( i.e. brain tumor or metastatic tumor ) o very common in older animals
Inflammation/Infection ( bacterial, viral, fungal, protozoal, rickettsial )
Degeneration ( cerebrovascular accident—stroke )
Systemic causes
Seizures can occur secondary to conditions away from the brain , stemming from different body systems other than the nervous system. Some common systemic causes of seizures include:
Hypoglycemia ( low blood sugar ) o very common in puppies
Hepatic Encephalopathy ( liver shunts )
Electrolyte Disturbances
Uremia ( kidney malfunction )
Hypoxia ( lack of oxygen )
Hyperlipidemia ( too much fat in the blood )
December 2011

Hyperthermia ( Dangerously high temperature—heat stroke )
Intestinal Parasites
Toxins ( lead, caffeine, xylitol in sweeteners, some plants/bugs )
Epilepsy
A seizure syndrome that is definitively none of the above conditions is termed idiopathic epilepsy . It is a diagnosis of exclusion. The underlying cause has yet to be defined. Most dogs having their first-ever seizure between 1-6 years old will most likely have epilepsy . Most epileptic pets have generalized seizures. If an epileptic pet is known to have partial seizures, the characteristics of the partial seizures usually do not change. Many owners have seen a prodromal phase , that is, something their pet commonly does immediately before the seizure begins.
Sometimes this is restlessness, hiding in a room, or trying to hide behind a piece of furniture.
How Can We Treat Seizures?
Veterinarians can treat pets that arrive in the middle of a seizure ( ictus ) with intravenous medication immediately. This will quell the seizure activity in the brain.
Before your veterinarian determines the best way to manage your pet’s seizures long-term, he will obtain some basic answers through blood work, urine analysis, x-rays, ultrasound, MRI , spinal fluid analysis, or a combination of these. Magnetic Resonance Imaging
( MRI ) is the gold standard in brain imaging diagnostics.
There are many anti-convulsant drugs available to pets through your veterinarian. Anti-convulsant drugs are used to “control & limit” seizures to as few & as far between as possible . Epileptic seizures can never be cured.
Epileptic pets commonly have seizure intervals that range from 1x/week to
1x/few months. Excellent “control” is about 1 seizure per month which translates into only 12 seizures per year. You should record the seizures by date, time of day, what it looked like, & how long it lasted . Your records will help your veterinarian control your pet’s seizures.
Once an epileptic patient is placed on a medication to control seizures, DO NOT STOP unless instructed by your veterinarian; stopping the medication on your own will cause MORE
SEIZURES! Periodically, pets need to be evaluated for drug effectiveness & monitored for any adverse signs. It is common for seizure frequency to increase over time. Therefore, medication may be increased or a second ( or third ) anti-convulsant drug may be added.
Seizures at Home—When is it an Emergency?
It is important not to put yourself or others in danger around a seizuring pet. You may get bitten during involuntary jaw snapping. During post-ictal disorientation your pet may not recognize you & may snap. Other pets should be kept away from a seizuring animal. It is very rare but another pet in the house may become aggressive towards the seizuring animal. However, there are some emergency situations in which you need to get your pet to the veterinarian immediately:
December 2011

-
( called, Status epilepticus ). A pet seizuring for 30 minutes will likely suffer permanent brain damage, overheating, respiratory arrest, cardiac arrest, organ failure, coma, &/or death.
-
( called, cluster seizures )
Your veterinarian may also prescribe oral or rectal Valium ( diazepam ). Rectal Valium can be compounded into suppositories. The idea was originally used as a safe & effective method to quell seizures in children. It has been adapted successfully for use in pets.
Conclusion
Seizures are the most common neurologic disorder seen in dogs & cats. There are several types of seizures depending on what part of the brain is affected & how the abnormal electrical activity was initiated. Idiopathic epilepsy is the most common cause of seizures in dogs 1-6 years old.
Most cats with seizures have an underlying identifiable cause but idiopathic epilepsy does occur in cats.
Periodically, pets need to be evaluated for drug effectiveness & monitored for any adverse signs.
It is common for seizure frequency to increase over time. Therefore, medication may be increased or a second ( or third ) anti-convulsant drug may be added.
Effective management of seizures depends on the teamwork between your veterinarian & you!
Your active participation along with proper treatment will result in the best control possible for your pet.
Michael Funk, DVM
References
Dewey CW. A practical guide to canine & feline neurology. 2 nd ed. 2008.
DeLahunta A, Glass E. Veterinary neurology and clinical neurology. 3 rd ed. 2009. http://accg.xplorex.com/page169.htm. http://www.123rf.com/photo_5813425_emergency-symbol.html http://nerveregenerating.com
Munana KR. Current approaches to seizure management. ACVIM 2010.
Ward EE. LifeLearn, inc. 2002.
December 2011