Pompe Disease is an inherited metabolic disorder affecting Lapponian Herders. Glycogen is the primary carbohydrate used by the body for energy. Affected dogs do not have sufficient enzymes to break down glycogen causing accumulation of glycogen in the multiple organs, including muscle, liver, heart and brain. Affected puppies typically present at about 6 months of age with generalized muscle weakness. Dogs with this disease develop an enlarged heart and dilated esophagus (megaesophagus). Megaesophagus causes regurgitation and vomiting and predisposes dogs to aspiration pneumonia. Over time the muscle weakness and regurgitation/vomiting worsen. Dogs may also have an unusual sounding bark, pant excessively, and have difficulty breathing. Dogs usually are euthanized or die of heart failure by 1.5 years of age.