Centronuclear Myopathy (CNM) – Labrador Retriever

Centronuclear Myopathy (CNM), also known as Type II Fiber Deficiency, Hereditary Myopathy of Labrador Retrievers (HMLR), or Autosomal Recessive Muscular Dystrophy, is a hereditary neuromuscular disorder that primarily affects Labrador Retrievers. It is caused by a recessive mutation in the HACD1 gene (also known as PTPLA), which disrupts normal muscle fiber formation. The condition is characterized by muscle weakness and wasting and usually becomes apparent during puppyhood.

Puppies with CNM are born without symptoms, and during the first few weeks they appear normal. From the second month of life, however, differences become noticeable compared to their healthy littermates. Affected puppies develop muscle weakness and exercise intolerance, which worsen with stress or cold. For some dogs, even a one- to two-minute walk at their own pace can be too much. Muscle loss (atrophy) also occurs, most visibly in the thighs and in the masticatory muscles of the head (particularly the temporal muscle, located between the eye and ear). Due to this weakness, many affected dogs carry their heads low and develop a rounded (arched) back. In addition to these clinical signs, a veterinarian performing a neurological exam will often find that the knee-jerk reflex is absent. Treatment is not available.

Pubmed ID: 15829503

Year published: 2005

Omia ID: 1374

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