WHAT IS SKELETAL MUSCLE MYOPATHY?
Skeletal muscle myopathy is a hereditary muscle disorder in which there is a deficiency of type II muscle fibers leading to a notable decrease in skeletal muscle mass. Although several breeds of dogs have been observed to demonstrate similar disorders, this condition is only seen in Labrador retrievers and was first reported and described in 1976. In 1981, the same researchers characterized the mode of inheritance in Labradors and since that time the condition has been referred to as “Hereditary Myopathy of Labrador Retrievers” (HMLR). Other names for HMLR include muscular dystrophy, myotonia, generalized muscle weakness, polyneuropathy, and hereditary myopathy. WHAT ARE THE SYMPTOMS OF HMLR? Muscle weakness, abnormal gait and posture, and a decrease in tolerance to exercise are the most common symptoms affecting Labradors with HMLR. On the average, onset of symptoms usually occur at 3-4 months of age, however, some dogs demonstrate symptoms as early as 6-8 weeks or as late as 6-7 mont
