Centronuclear myopathy in Labrador Retrievers is a recessively-inherited muscular disease. This disease was previously known as Labrador muscular myopathy. The disease is characterized by early onset muscular problems such as awkward gait, fatigue, and difficulty eating. Puppies are born apparently normal; however, it quickly becomes evident that there is problem. The puppy will often not gain weight adequately, due to decreased muscle tone in the esophagus. Within 2 to 5 months, the disease has usually progressed to display the full range of symptoms. This condition is exacerbated in cold conditions. Unfortunately, there is no cure for CNM, as the dog will never develop properly functioning muscle tissue. The dog usually has a normal life span, however, he will always be plagued with the symptoms.

• Labrador Retriever

A (CLEAR/NORMAL): These dogs have two copies of the normal gene and will neither develop CNM nor pass this mutation to their offspring.

B (CARRIER/NOT AFFECTED): These dogs have one copy of the normal gene and one copy of the mutation associated with this disease. They will not develop CNM but will, if bred, pass the mutation to 50% of its offspring, on average.

C (AT RISK/AFFECTED): These dogs have two copies of the mutation associated with this disease and are susceptible to develop insufficient muscle function.