The occurrence of multiple seizures is called epilepsy. Since these can be caused by various causes, a distinction is made between symptomatic and idiopathic epilepsy.
Forms of Epilepsy
Symptomatic Epilepsy - Seizures are triggered by metabolic disorders (e.g. hypoglycaemical) or anatomical changes in the brain (e.g. brain tumor).
Idiopathic Epilepsy -Seizures are triggered by disturbances in brain functions, tissue changes are not recognizable. Only idiopathic epilepsy is regarded as epilepsy in the narrower sense.
As a rule, idiopathic epilepsy appears for the first time with an age of 1 to 3 years. All breeds and mixes can be affected. A genetic predisposition has been proven for German Shepherds, Beagles, Retrievers, Bernese Mountain Dogs and Boxers. It is suspected, that several genes are involved in inheritance.
To clarify the hereditary components of epilepsy, the University of Veterinary Medicine Hannover, Foundation need samples from dogs affected with idiopathic epilepsy as well as (preferred old) non-affected dogs. As the diagnosis has to be confirmed, they also need copies of veterinary reports for each sample sent in. Please provide a translation in German or English if the reports are in a foreign language.
Seizures can be preceded by the so-called aura, a time in which the dog behaves differently (e.g. restlessness, fear). The actual epileptic seizure occurs as a result of undirected electrical discharges within the nerve cells. Depending on the size of the affected brain area, the externally visible episodes are different:
- partially simple seizure: only one part of the body, e.g. a leg, is affected by the seizure
- partially complex seizure: the consciousness of the dog is limited and behavioral disorders occur
- (e.g. snapping at non-existent flies)
- generalized seizure: The loss or severe change of consciousness and changes in muscle tone are characteristic. The dog lays down and shows tension and twitching of the limbs and jaw. Salivation, uncontrolled urination and feces are possible.
- Status epilepticus: Seizures last longer than 5 minutes or occur several times in a row.
Since there are no external changes, idiopathic epilepsy can only be diagnosed after ruling all other possible causes (= symptomatic epilepsy) out.
Abnormal electrical discharges destroy nerve cells with every seizure. Also abnormal discharge patterns consolidate, which favors the occurrence of new seizures. An early therapy is therefore most mandatory. The main anti-epileptic drugs used for dogs are phenobarbital and potassium bromide. By adjusting the dosage side effects are meant to be kept at a minimum. There is no cure. Therefore the medication usually has to be given for life. Only some of the patients become seizure-free, in some cases the frequency and severity of the episodes are reduced but there are also known cases of resistance to therapy.