Glycogen storage disease Ia is an inherited metabolic disorder affecting dogs. 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 organs of the dog, including the liver, heart and kidneys. Many affected dogs die In Utero or at birth resulting in small litter sizes with mummified fetuses and stillborn puppies. Symptoms in affected puppies that survive include failure to thrive, lethargy, low blood sugar, enlarged liver, coma and difficulty breathing. Without nutritional therapy affected dogs die within 2 months of age. Even with nutritional therapy affected dogs rarely survive to 6 months of age.