Seizures in Dogs by Dr. Jennifer Noll

Seizures are a common neurological disorder in dogs.  A seizure is defined as a transient involuntary clinical event resulting from excessive and synchronous discharge of neurons in the cortex.  This essentially means that there is abnormal and excessive activity involving the neurons in the brain resulting in the symptoms we recognize as a seizure.

Seizures can be either generalized (“grand mal”) or focal.  Generalized seizures result in loss of consciousness and frequently involve involuntary movement like paddling of the limbs.  Dogs can also urinate and/or defecate during the event.  Many dogs who have generalized seizures will also exhibit pre-ictal (before the seizure) and post-ictal (after the seizure) behavior abnormalities.  Dogs in the pre-ictal period may be anxious or show other behavior changes.  Dogs in the post-ictal period will often be disoriented and weak and their vision may be impaired.  This period can last from minutes to hours and even days in some cases.  Focal seizures can manifest in many ways, and may be as subtle as behavior changes to something more obvious like facial twitching.

Seizures must be differentiated from other conditions that can cause loss of consciousness, the most common being heart disease.  Dogs with heart disease who experience an arrhythmia (abnormal heart rhythm) can collapse and lose consciousness as well.  They may also urinate and defecate.  These episodes are usually brief and the dogs recover quickly without exhibiting post-ictal behavior.

The most common primary neurological cause of seizures in dogs 1-5 years in age is idiopathic epilepsy.  Idiopathic epilepsy is repeated seizures due to excessive neuronal activity in the brain without any underlying cause.  Dogs less than one year old are more likely to have a developmental disease or viral infection causing the seizure.  Dogs who have a first seizure when they are older than 5 years are more likely to have a brain tumor, but there are many other causes for seizures including inflammatory diseases and bacterial, protozoal and fungal infections.

There are numerous other conditions that can lead to the development of seizures as well.  Exposure to certain toxins will cause seizures (lead, moldy foods, insecticides, human medications).  Metabolic disturbances like low blood sugar, low blood calcium can cause seizures.  Dogs with certain types of liver disease can develop seizures.

Dogs who have a seizure for the first time should be immediately evaluated by a veterinarian. Initial work-up involves a thorough neurological exam and basic blood work including a CBC (complete blood cell count), chemistry panel and urinalysis.  Additional blood work might include a bile acids test to assess liver function, thyroid levels or lead levels.  If diagnostics results are all normal, frequently the dog is monitored to see how soon (if at all) he will have another seizure.

Dogs who have a single seizure that lasts for more than 5 minutes or who have three or more shorter seizures in a 24 hour period should also seek immediate veterinary care.  These dogs are often already on anti-convulsant therapy in which case the medication may need to be adjusted.

When a dog has a seizure, it is very important to stay away from his mouth.  Dogs can chew/snap during a seizure and can inadvertently injure owners.  Dogs will not swallow their tongue and rarely even bite the tongue, so do not touch the mouth.  If the dog is on a hard floor or on furniture where he might fall off onto a hard floor, move him only if it is safe to do so.  A towel or blanket can be placed temporarily over the head to protect the owner from the jaws.  If the dog is already snapping his jaws then he should be left alone.  Seizures are normally finite in length so give the seizure time to pass.  If active seizure activity is still occurring after five minutes, then the dog should be taken to the nearest veterinary hospital.  There is risk for brain damage and also overheating with subsequent organ damage if seizure activity is prolonged.  Remember that dogs are not conscious during seizure events and are not aware of their surroundings, so even the nicest dogs can bite their owners during the episode.

We are fortunate to have excellent veterinary neurologists in both New Hampshire and Massachusetts.  If the underlying cause for the seizures cannot be determined with basic testing or the seizures are difficult to control with the more common anticonvulsant medications, then referral to a neurologist is always as option.