Genetic basis of Adult Paroxysmal Dyskinesia - is often an autosomal recessive genetic disorder identified in some dog breeds, such as Soft-coated Wheaten Terriers. It is caused by mutations in specific genes, notably the PIGN gene with a documented substitution mutation (c.398 C>T in exon 3) in Soft-coated Wheaten Terriers. This means affected dogs inherit two copies of the mutated gene (one from each parent), while carriers have one copy and do not show clinical signs but can pass on the mutation. Genetic testing is available for certain breeds to identify carriers and affected dogs.
Pathophysiology - The disorder is characterized by episodes of abnormal involuntary movements (dyskinesia) including hyperkinesia (increased muscle activity) and dystonia (repetitive muscle contractions or twitching). Episodes are paroxysmal—they happen suddenly and recur frequently, lasting from several minutes to hours. Unlike epilepsy, affected dogs remain conscious during these episodes. Episodes are often triggered by excitement or stress but not exercise.
Complications - Dogs experience episodic movement disturbances such as increased muscle tone, twitching, and repetitive movements. The frequency and duration of episodes can vary, sometimes occurring more than ten times per day. Although neurological in nature, the disease is different from seizures as consciousness is preserved. There is no known cure; management is supportive and may include anticonvulsant medications to reduce frequency or severity of episodes.
Why This Matters to Breeders and Vets - Breeders: Genetic testing can identify carrier dogs and avoid breeding between carriers, which helps reduce incidence of the disease in the breed population. Veterinarians: Correct diagnosis distinguishes PxD from epilepsy and other neurological disorders, guiding appropriate management and treatment. Awareness helps improve quality of life and prevents unnecessary treatment trials or euthanasia based on misdiagnosis.
Summary - Adult Paroxysmal Dyskinesia is a genetic movement disorder in dogs, exemplified by Soft-coated Wheaten Terriers, caused by recessive mutations (notably in the PIGN gene) that lead to episodic abnormal involuntary movements without loss of consciousness. The condition is debilitating but not life-threatening, and while no cure exists, management may improve quality of life. Genetic testing is crucial for breeders to avoid producing affected dogs and for vets to accurately diagnose and treat the condition.