Seizures in Dogs and Cats

     A seizure is involuntary behavior that is caused by abnormal brain activity. Seizures may involve loss of consciousness, involuntary muscle activity affecting one part of the body, such as the face or whole body, sustained muscle contractions, alternating limpness, stiffness, inappropriate behavior – gum chewing, fly biting or attacking other pets or family members. Some seizures are one time events or may occur repeatedly over the course of weeks or months. The most important clue in determining if your pet has had a seizure or not is if they appear disoriented after the episode. This is otherwise known as the post-ictal phase.

     The causes for seizures differ based upon age and history – young animals causes include low blood sugar, liver shunts or improper brain development. In older pets we become concerned about brain tumors, infections, and/or autoimmune diseases. In both age groups we are concerned about toxin exposure such as chocolate ingestion, recreational drugs, pesticides, flea or tick medications or other infectious causes. Some breeds of dogs develop idiopathic epilepsy (or cause is unknown) – breeds include Labradors, Goldens, Bernese mountain dogs and poodles. Cats however require more advanced diagnostics which include spinal fluid analysis to determine infectious causes (toxoplasmosis) along with imaging.

     Diagnosis starts with a medical history, it is very important to note when your pet had a seizure, the duration, intensity and frequency of the seizure. Laboratory tests are necessary to help diagnose the cause of seizures if there is a cause outside of the brain. Additionally some dogs may require more advanced testing if the problem is located inside the brain. Tests include obtaining a sample of spinal fluid, performing an MRI (magnetic resonance imaging) or CT (computed tomography).

     Some dogs may have a single seizure and may not require further medications. Dogs that require medication have seizures more than once a month, or have had multiple seizures in one day. Medications may cause the pet to be sleepy at the beginning but they will acclimate or become used to the drug over time. Many pets remain on antiseizure medications for life and require regular serum drug levels to ensure proper drug dosaging to prevent seizures from “breaking through.” If your dog has a seizure longer than 5 – 10 minutes or is in a state of continuous seizures these dogs need to be seen by a veterinarian immediately.

Caroline Li, DVM