Myotonia Congenita in Dogs
Myotonia Congenita is a hereditary disorder characterized by the delay of skeletal muscle relaxation following the cessation of a voluntary activity.
The delay in skeletal muscle relaxation is not accompanied by pain or cramping. Affected animals have significant excessive growth of the muscles (muscle hypertrophy). They also have a stiff, stilted gait that improves with exercise. Difficulty in swallowing, excessive salivation and an abnormal bark are often present.
All affected Miniature Schnauzers have overshot upper jaws and abnormal dentition but that is not typical of myotonia in other breeds of dogs and in other species. The disorder is inherited as a simple autosomal trait. A single mutation in the gene encoding the chloride channel for skeletal muscles appears to be responsible for the clinical signs seen.
There is no known cure for the disorder but certain medications may help mange the symptoms and improve the dog’s quality of life.