Centronuclear myopathy (CNM)

Centronuclear myopathy (CNM) in Labrador Retrievers, formerly known as hereditary myopathy in Labrador Retrievers (HMLR), was described in the 1970ies for the first time. CNM as a disease causes dysplasia of the dogs muscles. Therefore, affected dogs lack tendon reflexes and gain less weight than puppys of the same age (4 weeks). Obvious symptoms of HMLR first occur at weeks 12 to 20 and include general amyosthenia, aberrant bearing, awkward gait and trouble with ingestion. Affected animals exhibit low stamina and collapse when exposed to coldness. Stress causes amyotrophia, that affects head muscles at times. The same disease appears in Great Danes. \nAnother variant has been found to be assoziated with myopathy in the breed German Hunting Terrier. In this breed, the disease is also called Excercise induced metabolic myopathy (EIMM). EIMM is caused by an autosomal recessive inherited deficiency of acyl-CoA dehydrogenase (VLCAD) and therefore of the fatty acid oxidation which results in insufficient energy production in the muscles. Affected dogs show signs of exercise induced weakness, muscle pain, rhabdomyolysis and brownish discoloration of the urine during or after exercise. That’s the reason why these dogs should not be used as hunting dogs since they collapse and develop tetraparesis to tetraplegia after 30 to 120 minutes of exercise. Due to muscle damage, blood analysis show increased values of creatine kinase activity (CK) and alanine transaminase activity (ALT) as well as increased concentrations of tetradecenoylcarnitine (C14:1). First symptoms could be observed at the age of 7 to 24 months. \n\n