Epilepsy, Idiopathic or Genetic, in Dogs
Epilepsy is a brain disorder that causes the dog to have sudden, uncontrolled, recurring physical attacks, with or without loss of consciousness. This may sometimes occur for unknown reasons (idiopathic) or due to genetic abnormalities. However, idiopathic epilepsy is often characterized by structural brain lesions and is more likely seen in male dogs. If left untreated, the seizures may become more severe and frequent.
Symptoms and Types
Seizures are usually preceded by a short aura (or focal onset). When this occurs the dog may appear fightened and dazed, or it may hide or seek attention. One the seizure(s) begin, the dog will fall on its side, become stiff, chomp its jaw, salivate profusely, urinate, defecate, vocalize, and/or paddle with all four limbs. These seizure activities generally last between 30 and 90 seconds.
Seizures most often occur while the patient is resting or asleep, often at night or in early morning. In addition, most dogs recover by the time you bring the dog to the veterinarian for examination.
Generally, the younger the dog is, the more severe the epilepsy will be. As a rule, when onset is before age 2, the condition responds positively to medication. Behavior following the seizure, known as postictal behavior, include periods of confusion and disorientation, aimless wandering, compulsive behavior, blindness, pacing, increased thirst (polydipsia) and increased appetite (polyphagia). Recovery following the seizure may be immediate, or it may take up to 24 hours.
Dogs with established epilepsy can have cluster seizures at regular intervals of one to four weeks. This is particularly evident in large-breed dogs.
Idiopathic epilepsy is genetic in many dog breeds and is familial; meaning that it runs in certain families or lines of animals. Breeds most prone to idiopathic epilepsy include the Beagle, Keeshond, Belgian Tervuren, Golden Retriever, Labrador Retriever, Vizsla and Shetland Sheepdog. Multiple genes and recessive modes of inheritance are suggested in the Bernese Mountain Dog and Labrador Retriever, while non-gender hormone recessive traits has been proposed in the Vizsla and Irish Wolfhound. There are also recessive traits in the English Springer Spaniel which can lead to epilepsy, but it does not appear to affect all members of the family. Seizures are mainly focal (involving localized areas of the brain) in the Finnish Spitz.
The characteristics associated with genetic epilepsy usually manifests from 10 months to 3 years of age, but has been reported as early as six months and as late as five years.
The two most important factors in the diagnosis of idiopathic epilepsy is the age at onset and the seizure pattern (type and frequency). If your dog has more than two seizures within the first week of onset, your veterinarian will probably consider a diagnosis other than idiopathic epilepsy. If the seizures occur when the dog is younger than six months or older than five years, it may be metabolic or intracrainal (within the skull) in origin; this will rule out hypoglycemia in older dogs. Focal seizures or the presence of neurologic deficits, meanwhile, indicate structural intracranial disease.