Epilepsy

Epilepsy is probably the most frequent reason why the dog owners are looking for the help of neurologist. Epileptic seizure is a reaction of a brain when the excitation of the brain cells is exceeding the inhibition. If the whole brain is involved in the seizure, the generalised seizure is seen. If just part of the brain is affected by the seizure activity the seizure is called focal. The generalised seizure is usually connected with loss of consciousness, the animal is laying on the side, the limbs are irregularly contracting, the head and neck might be extended, the facial and masticatory muscle are twitching, salivation, urination and defecation might occur. The focal seizure is usually characterised by preserved consciousness and just one part or side of the body is showing abnormal movements. Both types of seizures are usually short 1-2 minute duration. The dog is frequently abnormal also after seizure for some time and if the seizure is long it might take 1-2 days to recover fully. Dogs and cats might be tired, disoriented, hyperactive, hungry, thirsty, blind, death, unusually aggressive or friendly, or have signs of paralysis after the seizure. If seizure is not longer than 5 minutes and is not frequent, it usually does not cause any permanent changes in the brain. Status epilepticus (continuous seizure) is diagnosed if the seizure is longer than 30 minutes and is considered an emergency situation as it can cause changes in the brain and other complications in liver, lungs, heart and other organs. Cluster of seizures is defined by occurrence of 2 or more separate seizures within 24 hours and might also need help from veterinarian.

When we say epilepsy in veterinary medicine we usually mean the idiopathic-inherited epilepsy. It is also sometimes called functional, hereditary, functional or primary epilepsy also. Inherited epilepsy in animals is diagnosed when the dog or cat has normal brain on magnetic resonance imaging and does not have any metabolic disorder in blood examination. The electroencephalographic examination might detect epileptic activity or be normal between the two seizures. The only way to treat the idiopathic epilepsy is with the help of epileptic medication if the seizures are frequent and severe. If seizures are mild, short and seldom the epilepsy can be left untreated and is not necessary getting worse with time. The inherited epilepsy might occur in juvenile age (Lagotto romagnolo), young adult age (majority of the breeds) or have a late onset (Pyrenean shepherd dog). As in humans also in dogs and cats the inherited epilepsies are presumed to be caused by abnormalities in the ion channels on the membranes of the nerve cells. Till today there have not been identified any gene mutations in dogs with idiopathic epilepsy, therefore the exact pattern of inheritance is unknown.

Epileptic seizures might be also caused by disease in brain such as brain trauma, infection or tumor. In these situations the seizure is the result of the underlying disease and in order to help the patient the underlying disease has to be treated. The antiepileptic medication is just the addition to the therapy plan in these cases. At last the metabolic-toxic conditions such as low blood sugar or ingestion of toxins might cause seizures. These diseases are usually easily diagnosed from blood examination and from the information from history.

From the text above it is easy to conclude that in dogs and cats with epilepsy the neurological and blood examinations should be performed in all cases. In cases where brain disease is suspected to cause the epileptic seizures the electroencephalography and the magnetic resonance imaging is indicated in order to define what disease has caused the seizures and what would be the most effective treatment plan for the patient.

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