Myotonia Congenita
Myotonia occurs as a congenital problem in various breeds of dogs. The prolonged muscle contraction is thought to be due to an abnormal muscle cell membrane that supports persistent depolarization. Animals with myotonia have sustained muscle contraction, which is initiated voluntarily or with stimulation, and sustained involuntarily.
French bulldogs have been noted to have a unique variant of myotonia congenita that may result in decreased muscle atrophy.
French bulldogs have been noted to have a unique variant of myotonia congenita that may result in decreased muscle atrophy.
Age of Onset:
Congenital: First few weeks of life
Acquired: any age
-Hyperadrenocorticism-associated - usually older animals
Congenital: First few weeks of life
Acquired: any age
-Hyperadrenocorticism-associated - usually older animals
Sex Predisposition:
Any sex of animal can be affected
Any sex of animal can be affected
Clinical Course:
Muscle “stiffness” manifested by limb extension and short step distances is most prominent after periods of rest and will often reduce in severity as the dog repeatedly uses their muscles during movement.
Muscle “stiffness” manifested by limb extension and short step distances is most prominent after periods of rest and will often reduce in severity as the dog repeatedly uses their muscles during movement.
Clinical Signs:
Posture and Appearance
Muscle dimpling may occur with direct muscle percussion
Extended limbs with movement
Movement
Short-”stilted” gait
Short step or interstep distances
Bunny-hopping gait
Stiffness and extensor rigidity of the limbs
Muscle Atrophy
Appendicular muscle hypertrophy
Glossal hypertrophy
Posture and Appearance
Muscle dimpling may occur with direct muscle percussion
Extended limbs with movement
Movement
Short-”stilted” gait
Short step or interstep distances
Bunny-hopping gait
Stiffness and extensor rigidity of the limbs
Muscle Atrophy
Appendicular muscle hypertrophy
Glossal hypertrophy
Diffuse neuromuscular
Autosomal recessive mutation in chloride channel (CLCN1) gene. French bulldogs have also been noted to have a mutation in the cAMP phosphodiesterase gene (PDE4C) which may result in decreased muscle atrophy.
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