Epilepsy in Dogs
Epilepsy is a neurological condition which occurs in many animals, including dogs. It is caused by sporadic electrical storms in the brain which result in seizures or fitting. Seizures are a sudden involuntary increase in muscle tone and/or movement. They vary from being brief and nearly undetectable episodes, to long periods of vigorous shaking. Epilepsy is often an inherited condition and is the most common brain disorder in dogs. The incidence is much higher in some breeds, e.g. the English Springer Spaniel.
TYPES OF SEIZURE
Status epilepticus: A life-threatening condition in which there is one continuous seizure lasting longer than 10 minutes, or recurrent seizures with no period of normal consciousness.
Cluster seizure: Multiple seizures within a 24-hour period which may also be life threatening.
Seizures are further classified as focal, generalized, and focal with secondary generalization. Focal seizures affect only a small part of the brain, whereas generalized seizures tend to affect both sides of the brain.
As the frequency of seizures increases, the probability of damage to the brain neurons also increases. This in turn increases the likelihood that the dog will seize again.
STAGES OF A SEIZURE
1) The Prodome: This stage precedes the seizure by hours or days and is characterized by changes in the dog’s mood or behaviour.
2) The Aura: This signals the start of a seizure. The dog may show nervousness, whining, trembling, salivation, restlessness, hiding and apprehension.
3) The Ictus, the actual seizure: This is a period of intense physical activity usually lasting 45 seconds to 3 minutes. The dog may lose consciousness and show teeth gnashing, uncontrolled thrashing of limbs, drooling, whining, foot paddling, urination and defecation.
4) The Post Ictus/Ictal: This is the stage after the seizure. The dog may eat or drink excessively, continuously pace, or appear blind and deaf.
TYPES OF EPILEPSY
There are three types of epilepsy that can affect dogs; reactive, secondary and primary. Symptomatic (secondary) means that a cause has been identified, whereas idiopathic (primary) means there is no apparent cause.
Reactive seizures are caused by metabolic problems, such as low blood sugar or kidney or liver failure. Secondary epilepsy seizures are caused by problems such as a brain tumours, strokes, or other trauma. In primary epilepsy, there is no known cause – this is usually diagnosed by eliminating other possible causes for the seizures.
Physical symptoms may include the following –
• Weak pulse
• Low blood pressure
• Muscle contractions
• Trembling, shaking or twitching
• Difficulty with breathing
• Obvious seizures
• Swelling in the brain
• Obsessive and compulsive behaviors
As with most dog diseases, diagnosing the condition early and getting appropriate treatment are vital to overall health and wellness. With epilepsy, younger dogs are more at risk from severe forms of epilepsy, including primary epilepsy. Diagnosis will require laboratory and biochemical tests. These may reveal the following –
• Low blood sugar
• Kidney failure
• Liver failure
• Fatty liver
• Systemic diseases
• Infectious blood diseases
• Viral diseases
• Fungal diseases
DEVELOPMENT OF THE DISEASE
Effectively, anything that disrupts brain circuitry can affect the development of epilepsy. This includes the current pattern of seizures because they influence future development of the seizures. Other factors include how old a dog is when it first seizes, and the frequency and outcome of re-occurring seizures.
Drugs that can be used when treating epilepsy in dogs include corticosteroids, anti-epileptic and anticonvulsant medications. These can help reduce the frequency or intensity of seizures. The medication will depend on the type of epilepsy the animal is suffering and will also take into account any other underlying health concerns.
Medications include –
• Potassium Bromide
• Primidone (Mysoline)
• Valium (Diazepam)
• Keppra (Levetiracetam)
For some animals, surgery may be required to remove tumours contributing to the seizures.