What Is Glycogen Storage Disease Type II in Dogs?

Glycogen Storage Disease Type II (GSDII), also known as Pompe’s disease, is a rare hereditary disorder in dogs caused by a deficiency of enzymes that metabolise glycogen, a form of stored energy in muscles and the liver. This leads to dangerous accumulation of glycogen in tissues, which can enlarge organs and cause severe dysfunction, particularly of the heart, liver, and kidneys.

In affected dogs, the enzyme needed to convert glycogen into usable glucose is missing or defective, resulting in progressive muscle weakness and organ problems that often prove fatal, usually by the age of two. GSDII is inherited in an autosomal recessive pattern, meaning a dog must inherit gene faults from both parents to develop the disease. Dogs inheriting one faulty gene copy may be carriers without symptoms but can pass the condition on.

Recognising Affected Dog Breeds and Heredity

This condition primarily affects certain northern breeds, especially those in the Lapland dog group like the Finnish Lapphund puppies and Swedish Lapphund puppies. Understanding heredity is crucial: both parent dogs need to be carriers for puppies to be at risk. Responsible breeders should test breeding stock to prevent propagation of GSDII within the gene pool.

How Is Glycogen Storage Disease Type II Inherited?

The disorder follows an autosomal recessive inheritance pattern. This means:

• If both parents carry one copy of the faulty gene, puppies have a 25% chance of being affected, a 50% chance of being carriers, and a 25% chance of being clear of the condition.
• If only one parent is a carrier, puppies will not develop the disease but half may be carriers.
• If neither parent carries the gene, none of the puppies will have the condition or be carriers.

This genetic pattern highlights the importance of testing prior to breeding to avoid producing affected pups and to reduce the prevalence of this fatal disease in affected breeds.

Testing Dogs For Glycogen Storage Disease Type II

Testing involves collecting a DNA sample, typically via a vet, which is sent to approved laboratories. The Kennel Club provides a DNA screening scheme database where owners and breeders can check if their dog's breed has recognised hereditary conditions including GSDII. For UK testing laboratories, see The Kennel Club's approved laboratories list.

Living Responsibly With Glycogen Storage Disease Risks

While GSDII in dogs is rare, its fatal nature demands responsible breeding practices and awareness. Testing breeding dogs helps prevent suffering and reduces disease spread. Owners and breeders should prioritise genetic health screening and select only non-carrier dogs for breeding. Early diagnosis supports better management and informed care decisions.

Key Points Summary

• GSDII is a hereditary, fatal enzyme deficiency leading to glycogen build-up in organs and muscles.
• Primarily affects northern breeds like Finnish and Swedish Lapphunds.
• Inherited autosomal recessive; both parents must carry gene faults for puppies to be affected.
• DNA testing is essential for responsible breeding.
• Preventing GSDII reduces suffering and maintains healthier breed populations.

Understanding and addressing Glycogen Storage Disease Type II is vital for breeders and owners of at-risk breeds. Using DNA tests from reputable sources and supporting ethical breeding protects future generations of dogs from this devastating disease.