Centronuclear Myopathy/Centronuclear Myopathy/Hereditary Labrador Retriever Myopathy/Inherited Centronuclear Myopathy
A form of muscular dystrophy that results from a deficiency of type II muscle fibers. Labrador Retrievers may also be affected by a subtype of centronuclear myopathy known as X-linked Myotubular Myopathy
Age of Onset: 6 weeks-8 months, signs typically apparent from 8-12 weeks of age
Sex Predisposition: Any sex of animal can be affected
Clinical Course:
Clinical signs typically worsen over time but may plateau after some months
Clinical signs typically worsen over time but may plateau after some months
Clinical Signs:
Behavioral/Mental Awareness
Exercise intolerance
Listless
Reluctant to exercise
No voracious appetite at weaning
Posture and Appearance
Head may be positioned closer to the ground
Posture is often kyphotic
Carpal overextension and carpal valgus
“cow hocked” appearance
Outward rotation of the forefeet
“Swimmer” position – sternal recumbency
Undersized
Inability to retract the penis
“flat” feet
Arched back(Kyphosis)
Muscle fasciculations in face and hindlimbs
Movement
Short steps
Bunny hopping gait in the pelvic limbs
Hypotonia
Collapse at exercise
Inability to stand
Acute tetraparesis
Stiff limbs
Slow gait
Spinal Reflexes
Patellar tendon reflex reduced or absent
Triceps tendon reflex absent
Extensor carpi reflex absent
Weak withdrawal reflexes
Special Functions (e.g. respiration; urination)
Regurgitation
Muscle Atrophy
Wasting of skeletal musculature
Atrophy of skeletal muscle on the head, neck, and legs
Other
Clinical signs may be worse in cold environments
Esophageal dilation/Megaesophagus
Behavioral/Mental Awareness
Exercise intolerance
Listless
Reluctant to exercise
No voracious appetite at weaning
Posture and Appearance
Head may be positioned closer to the ground
Posture is often kyphotic
Carpal overextension and carpal valgus
“cow hocked” appearance
Outward rotation of the forefeet
“Swimmer” position – sternal recumbency
Undersized
Inability to retract the penis
“flat” feet
Arched back(Kyphosis)
Muscle fasciculations in face and hindlimbs
Movement
Short steps
Bunny hopping gait in the pelvic limbs
Hypotonia
Collapse at exercise
Inability to stand
Acute tetraparesis
Stiff limbs
Slow gait
Spinal Reflexes
Patellar tendon reflex reduced or absent
Triceps tendon reflex absent
Extensor carpi reflex absent
Weak withdrawal reflexes
Special Functions (e.g. respiration; urination)
Regurgitation
Muscle Atrophy
Wasting of skeletal musculature
Atrophy of skeletal muscle on the head, neck, and legs
Other
Clinical signs may be worse in cold environments
Esophageal dilation/Megaesophagus
Neuromuscular
Autosomal recessive inheritance of PTPLA gene mutation. Often associated with yellow or black hair coats.
For breed specific genetic testing follow the links below:
https://vgl.ucdavis.edu/test/cnm-labrador
https://animalgenetics.com/dog-tests/canine-disorder-tests/23-cnm/
https://tests.dnacenter.com/testing-pets-vets/dog-dna-testing/inherited-disease-screening/centronuclear-myopathy-in-labrador-retrievers/
For breed specific genetic testing follow the links below:
https://vgl.ucdavis.edu/test/cnm-labrador
https://animalgenetics.com/dog-tests/canine-disorder-tests/23-cnm/
https://tests.dnacenter.com/testing-pets-vets/dog-dna-testing/inherited-disease-screening/centronuclear-myopathy-in-labrador-retrievers/
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