Paroxysmal exercise-induced dyskinesia (PED)

In the breed Shetland Sheepdog, a variant in the PCK2 (phosphoenolpyruvate caboxykinase 2) gene has been found to be associated with PED. Affected dogs show episodes of generalized ataxia with an unusual gait pattern (hypermetria) and muscular tension (hypertonia) of all limbs, reduced mentation and mild tremor. The episodes could vary from minutes to hours and are triggered by inner tension, like playing, after being startled by noise or hot weather. Laboratory tests indicate a mild lactic acidosis and lactaturia, mildly increased serum creatine kinase (CK) levels and hypoglycemia. \nStress management, a specific diet (gluten- and grain-free, seafood-bases with a high tryptophan content) as well as a pharmacological therapy with antiepileptic drugs (carbonic anhydrase inhibitors) can have an impact on episode frequency or even result in partial or complete suppression of the episodes. \n\nIn the breed Weimaraner, a variant in the tenascin-R (TNR) gene has been identified to cause PED and is inherited as an autosomal-recessive trait.\nAffected dogs show symptoms like abnormal gait characterized by increased muscle contractions (dystonia), ataxia and hypermetria, leading to occasional collapse. Kyphosis and low head carriage were also typical clinical signs. Some dogs also displayed intermittent anisocoria. The age of onset was 3 to 7 months. These abnormal episodes triggered by increased emotional excitement and exercise, can occur multiple times per day and last for 5 to 15 minutes. Resting physical and neurological examinations, muscle and nerve biopsies, electrophysiology as well as MRI were unremarkable.\n