Paroxysmal dyskinesia is a progressive inherited movement disorder affecting dogs. Affected dogs present around 2 years of age with intermittent episodes of uncontrolled muscle contractions resulting in repetitive involuntary flexion and extension of the limbs. Hind limbs are more commonly affected than front limbs. However, in severe cases, all four limbs are affected. Though flexing of limbs occurs in just a single leg or alternates from limb to limb in most dogs, some dogs may also experience flexion of both hind limbs simultaneously, resulting in collapse or weight bearing on the front limbs only. Episodes can last from minutes to hours and can occur from several times per day to once every several weeks. Dogs appear normal between episodes. In some dogs, excitement or stress may trigger an episode. The disease progresses with age and dogs are often euthanized within 2 years of diagnosis due to decreased quality of life.