Duchenne muscular dystrophy is an inherited disease affecting dogs. Affected dogs are unable to produce adequate amounts of a protein important for muscle contraction and relaxation. Clinical signs of affected dogs include generalized muscle Atrophy, a stiff or shuffling gait, difficulty standing, exercise intolerance and over flexion of the ankle joint. Affected dogs have difficulties feeding and often drool. Affected dogs are often significantly smaller than littermates by 6 weeks of age. Cardiac muscle is also compromised in affected dogs, potentially resulting in clinical heart disease.