Types of Epilepsy
There are two types of epilepsy: primary epilepsy and secondary epilepsy.
Primary epilepsy is also called idiopathic epilepsy (IE). There is not a definitive test for IE. It is diagnosed by excluding all other causes of seizures. Most dogs with idiopathic epilepsy begin seizing before the age of 5 years. Although a genetic link in border collies has not yet been identified, idiopathic epilepsy is more prevalent in certain families or lines indicating a heritable component.
Secondary epilepsy is a symptom of another underlying disease or injury. Trauma, hydrocephalus, toxins, infectious disease, metabolic conditions, cancer and storage diseases (such as neuronal ceroid lipofuscinosis) may all result in seizures. Some of these secondary forms of epilepsy may have a genetic cause, such as neuronal ceroid lipofuscinosis, but many others are not hereditary.
Primary epilepsy is also called idiopathic epilepsy (IE). There is not a definitive test for IE. It is diagnosed by excluding all other causes of seizures. Most dogs with idiopathic epilepsy begin seizing before the age of 5 years. Although a genetic link in border collies has not yet been identified, idiopathic epilepsy is more prevalent in certain families or lines indicating a heritable component.
Secondary epilepsy is a symptom of another underlying disease or injury. Trauma, hydrocephalus, toxins, infectious disease, metabolic conditions, cancer and storage diseases (such as neuronal ceroid lipofuscinosis) may all result in seizures. Some of these secondary forms of epilepsy may have a genetic cause, such as neuronal ceroid lipofuscinosis, but many others are not hereditary.
Types of Seizures
All seizures are caused by electrical disturbances in the brain. Depending on how and where in the brain they begin, seizures can be described as one of two types: generalized seizures or partial seizures.
Partial seizures are also known as focal or absence seizures. A dog experiencing a simple focal seizure may have twitching, aggression, vocalize or display "fly-catching" or tail chasing behavior.
Partial seizures are also known as focal or absence seizures. A dog experiencing a simple focal seizure may have twitching, aggression, vocalize or display "fly-catching" or tail chasing behavior.
Phases of a Seizure
Pre-Ictal or Aural Phase
This phase occurs hours or even days before the seizure itself. The dog may display small changes in behavior or mood. They may seem anxious or seek out to be near people more than usual. Some dogs may withdraw and avoid human interaction.
Ictal Phase
This is the phase that most people thing of when they think of a seizure.
Post Ictal Phase
This phase occurs once the seizure has finished. The dog may seem confused, pace, lose vision and/or hearing temporarily, or seem anxious. Some dogs become extremely hungry in the post ictal phase or just want to sleep. The post ictal phase may last for minutes, hours or even days after a seizure.
This phase occurs hours or even days before the seizure itself. The dog may display small changes in behavior or mood. They may seem anxious or seek out to be near people more than usual. Some dogs may withdraw and avoid human interaction.
Ictal Phase
This is the phase that most people thing of when they think of a seizure.
Post Ictal Phase
This phase occurs once the seizure has finished. The dog may seem confused, pace, lose vision and/or hearing temporarily, or seem anxious. Some dogs become extremely hungry in the post ictal phase or just want to sleep. The post ictal phase may last for minutes, hours or even days after a seizure.
Diagnosing Idiopathic Epilepsy
Idiopathic epilepsy is diagnosed by excluding all underlying disease or injury that could cause seizures. Blood tests (chemistry and complete blood count), urinalysis, MRI and cerebrospinal fluid analysis are tests commonly used to rule out underlying disease or injury.
Managing Epilepsy in Dogs
Dogs with idiopathic epilepsy can require treatment for life. There are several medications used to treat epilepsy and sometimes more than one drug is needed for adequate seizure control. Some dogs may be well controlled with medications, while some are not controlled despite multiple medications.
Border collies seem to be resistant to drugs commonly used to control epilepsy. One possible explanation for this resistance is variation in the ABCB1 gene that is believed to play a role in drug resistance in epilepsy (See J Vet Intern Med. 2011 May-Jun;25(3):484-9. doi: 10.1111/j.1939-1676.2011.0718.x. Epub 2011 Apr 12)
For a list of medications commonly used to treat epilepsy in dogs click here.
Border collies seem to be resistant to drugs commonly used to control epilepsy. One possible explanation for this resistance is variation in the ABCB1 gene that is believed to play a role in drug resistance in epilepsy (See J Vet Intern Med. 2011 May-Jun;25(3):484-9. doi: 10.1111/j.1939-1676.2011.0718.x. Epub 2011 Apr 12)
For a list of medications commonly used to treat epilepsy in dogs click here.
Genetics of Idiopathic Epilepsy
Although a genetic test for epilepsy in border collies has not yet been developed, idiopathic epilepsy does seem to be more prevalent in certain breeds, families, and lines indicating a heritable component. IE does not appear to follow simple inheritance patterns making it difficult (if not impossible) to eliminate carriers from breeding programs. Read more about the mode of inheritance of epilepsy here.