Glycogen Storage Disease in Dogs

Glycogen, often referred to as “animal starch” is the primary way by which mammals store energy. An enzyme called glucose-6-phosphatase handles converting the glycogen into glucose, which the body can then use as fuel. Rarely, some puppies can be born with a genetic deficiency in this enzyme. Without the action of glucose-6-phosphatase, the animal is unable to produce glucose on its own in response to changes in blood sugar. This leads to chronic low blood sugar. Also, since the animal cannot effectively break down glycogen and fat, both of these accumulate in the liver, kidneys and muscle, causing damage and impairing the proper function of these organs. The abundance of glycogen by-products has to go somewhere, and when it is processed via additional metabolic pathways, it can lead to other disorders like lactic acidosis and elevated triglycerides. Dogs with this condition do not usually survive past four months.

• Weakness
• Chronic low blood sugar
• Collapse
• Lethargy
• Enlarged liver
• Anorexia

Types

• I-a: occurs in toy breeds. Low body weight, lethargy and low blood sugar.
• II: occurs in Laplands. Gastrointestinal upset, weakness and heart trouble.
• III: occurs in German Shepards and Curly-Coated Retrievers. Weakness, low body weight and slight low blood sugar.
• IV: occurs in Springer Spaniels. Damage to red blood cells, urinary abnormalities.

Inherited genetic defect.

Owners who notice their new puppy failing to gain weight and seeming weak should see an appropriately skilled veterinarian as soon as possible. There are a multitude of possible reasons why your puppy is ill, and many of them may be curable. In the event that your dog does have Glycogenosis, the veterinarian will attempt to rule out similar diseases such as hepatitis, mucopolysaccharidosis, and ketoacidosis as a symptom of diabetes. First, a number of blood panels checking liver and kidney function will be performed. Blood sugar will be checked, and an insulin-production test may be given to rule out diabetes. As the veterinarian comes to suspect Glycogenosis, a genetic test will definitively diagnose this condition with a blood or saliva sample.

Unfortunately, Glycogenosis is always fatal. During the diagnostic process, there are a number of ways low blood sugar may be corrected, such as a high-carbohydrate diet and administration of dextrose intravenously. These are only short-term measure, and it is a rare occurrence for dogs afflicted with Glycogenosis to survive more than a year.

There is no cure for Glycogenosis, and many veterinarians deem it kinder to euthanize the dog rather than subject it to the suffering incurred as its condition deteriorates. A diet high in carbohydrates in conjunction with intravenous dextrose solutions can temporarily manage crises of low blood sugar, but is not a permanent solution. Dogs suspected of carrying the gene for Glycogenosis should not be bred, and the parents of the affected puppy should also be kept from breeding again. The owners of seemingly healthy dogs from that litter should be notified of the risk their dog is a carrier.