Seizures

The following article was written by Rachel Peeples.

Seizures are the outward manifestations of brain cell hyperactivity.   This hyperactivity disrupts the normal balance in the nerves of the body and leads to their overstimulation.  Seizures run the gamut from periods of unawareness to stereotypic behavior (like "fly-biting" ie snapping the jaws at nothing repeatedly) to the more commonly recognized generalized muscle contraction and convulsions with associated alterations in consciousness.

There is a myriad of causes of seizures.  Especially in the young dog or puppy, alterations in metabolism must be considered.  Excessively low blood sugar will cause seizures.  Problems with the liver (referred to as a liver shunt) will cause high blood levels of ammonia and seizures are a common result.  Especially in older dogs, kidney failure and liver failure can lead to build up of toxic body by-products in the blood causing seizures.  In nursing bitches, excessively low calcium can lead to seizures.  Endocrine abnormalities like hypothyroidism are also potential causes.   Finally, a number of toxins produce neurologic signs including seizures.   These are all considered extracranial causes, that is, the primary problem is not in the brain but is the result of the effects of another primary disease on the brain.

Intracranial causes are diseases of the brain itself.  Several breeds (German breeds like Dachshunds, short-haired pointers, Rottweilers; Tibetan Spaniel, etc) have congenital problems with abnormal storage of certain metabolic chemicals in brain cells.  Over time these build up and cause the brain cell to become dysfunctional and lead to seizures.   Any episode of reduced oxygen to the brain (shock, hit by car, reduced blood pressure, etc) can cause permanent damage to brain cells as can episodes of heatstroke, high fever, and anaphylaxis (severe, immediate allergic reaction).  These changes can create brain cell hyperactivity and result in seizures.  Cancer in or around the brain can directly (via invading them) or indirectly (through changes in blood flow and increase in pressure on the brain tissue) damage brain cells resulting in seizures.   Any infection (bacterial, viral, tick-borne like Ehrlichia, Rocky Mountain Spotted Fever, etc) of the brain or the membranes around the brain (called the meninges) can causes alterations in brain cell metabolism, blood flow, and environment resulting in seizures.  Trauma from being hit by a car or from being hit or kicked in the head (especially in very young puppies) can lead to seizures.

Epilepsy is probably the most common cause of seizures.   It is defined as a brain disorder characterized by recurrent seizures and that has NO abnormal brain cell structure but for some reason unknown at this time has abnormal brain function.  Epilepsy is genetic with the following breeds predisposed:   Beagle, the Belgain Shepherds (Tervurens, Malinois, etc), Border Collie, Boxer, (American) Cocker Spaniel, Collie, Dachshund, German Shepherd Dog, Golden Retriever, Ibizan Hound, Irish Setter, Keeshond, Labrador Retriever, Poodle, Saint Bernard, Shetland Sheepdog, Siberian Husky, (English) Springer Spaniel, Welsh Corgi (Pembroke and Cardigan),   and Wire-haired Fox Terrier.  Epilepsy typically manifests between 6 months and 2 years and is usually characterized by increasing frequency of seizures.  The seizures are usually of the generalized and convulsive type rather than the milder type.    Interestingly enough, most seizures happen when the dog is at rest (night and early morning usually).  Recovery period (called post-ictal) following a seizure ranges from immediate to 24 hours.  When the dog is not having a seizure or in the recovery period it is perfectly normal.  If untreated, seizures tend to increase in frequency averaging about one seizure per week.

Treatment depends on the cause of the seizure.  Metabolic conditions and toxins are treated appropriately and usually the seizures resolve.  Many of the congenital, oxygen deprivation, and excessive heat causes result in progressive, permanent changes and are often refractory to treatment.  Infectious causes are treated based on what they are -- ie bacterial with antibiotics, tick-borne with antimicrobials, etc.  Cancer is treated with chemotherapy or radiation therapy if the cancer is responsive to these protocols.  Epilepsy really has no specific treatment other than to control the seizures.

In all of these cases the seizures need to be controlled until the primary disease can be addressed or indefinitely in the case of epilepsy.  Phenobarbitol and potassium bromide are the two most common drugs used to control seizures.  Valium is not an option for treating seizures in dogs long-term because in the oral form it cannot reach high enough concentrations in the body of the dog to be effective.  It can be used intravenously in emergeny cases but not orally for maintenance.  Phenobarbitol and potassium bromide take weeks to months to reach a stable level in the dog so that seizures can be effectively controlled.  In the interim and periodically afterwards, bloodwork needs to be done to make sure that the level of drug in the dog's body stays at the proper level (high enough to work, low enough not to be toxic).  Some dogs become refractory to these medications making it very difficult to control the seizures.  As a rule the younger the onset of the seizures the harder it is to control the seizures.  There are hundreds of holistic and dietary protocols that have worked to eliminate seizures in dogs.  They are as individual as the dog that has the seizures and, thus, the best advice is to seek out a holistic veterinarian in order to develop an individualized protocol.  Some dogs respond to these protocols and never need medication.   Others have to have some medication to control the seizures.  

There is hope that in the near future geneticists will provide breeders with tests for the epilepsy gene thereby reducing the prevalence of epilepsy in the canine population.    Until then dogs that have epilepsy should not be bred.

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