Myostatin deficiency (whippet type) is an inherited muscular disorder affecting dogs. Dogs that inherit two copies of the Mutation associated with myostatin deficiency (whippet type) have broad chests and overly developed muscles especially of the neck and legs as well as an overbite. These dogs are easily discernible from unaffected littermates. Dogs that inherit one copy of the mutation have more muscling than dogs without the mutation but less muscling than dogs with two copies of the mutation. Dogs with one copy of the mutation tend to perform better when racing. Dogs with two copies of the mutation typically live normal lives but may be prone to muscle cramping of the shoulder and thigh muscles.