Idiopathic epilepsy in dogs
Idiopathic epilepsy is a disorder of recurring seizures of unknown cause. In some breeds, there is a genetic or inherited influence. For most dogs we do not know the cause of these epileptic seizures. All diagnostic tests used to search for the causes of seizures are normal in animals with idiopathic epilepsy. Idiopathic epilepsy is very uncommon and cats. It typically affects dogs from 1-5 years of age, but may develop at any age. Sometimes we can see small scar tissue in the brain, but often we see no inciting cause.
Animals with idiopathic epilepsy have recurring seizures. Most seizures last 1-3 minutes, and they can occur at any time of the day. Time between seizures can be as short as minutes, or as long as months. The Latin term “ictus” refers to a seizure. The time between seizures is called the interictal. Affected animals are normal between seizures, and do not have any neurological abnormalities on physical exam. The most common form of seizures is the grand mall seizure, in which the animal is unconscious and unresponsive. The legs are often rigidly stretched out or drawn up toward the body. The limbs may jerk or paddle as if running. Chewing motions, excessive salivation, urination or defecation may occur.
The diagnosis of idiopathic epilepsy requires eliminating all other diseases that can cause seizures. Routine laboratory tests, X-rays and EKGs are often performed. Animals with idiopathic epilepsy have normal test results. MRIs are used on people and on our pets to evaluate the architecture of the brain and to see if there are any lesions in the brain that could be responsible for the epileptic seizures.
Treatment is aimed at reducing the duration, severity and frequency of seizures. Several antiepileptic drugs are available to control seizures. These drugs are not initially prescribed, unless the seizures are frequent or of an abnormal duration. Drugs are also prescribed if the animal’s quality of life is impaired by the seizure activity. Not every animal with idiopathic epilepsy requires treatment. For instance, an animal that has experienced only a single isolated seizure is not started on medication. Instead, the affected animal may be monitored, and the frequency of any future seizures helps determine when to start therapy.
Prognosis for animals with idiopathic epilepsy is usually good, because many of the seizures can be controlled. Animals that are well controlled on anticonvulsant medications can live normal, healthy lives. The prognosis is guarded for animals with poorly controlled seizures.
Dr. Karsten Fostvedt is a veterinarian at St. Francis Pet Clinic in Ketchum.