Glycogen storage disease II in Lapland dogs

Abstract

Glycogen storage diseases (GSD) are rare disorders in animals. Five different types of GSDs have been reported in dogs and cats. They are all due to inborn errors in the function of enzymes involved in glycogen metabolism. GSD type II has been reported in Lapland dog and an autosomal recessive inheritance is suspected. GSD II develops as a result of decreased activity of lysosomal acid α‐glucosidase enzyme. In humans the clinical outcome is variable partly due to the variable amount of remaining activity of the enzyme and the disease has an infantile and late onset form. In Lapland dogs the pathology in GSD II is very similar to the infantile form with the exception of megaesophagus which is present in the affected dog, however, the clinical outcome is different from human.We examined a 1,5 year old female Lapland dog from a litter of three affected dogs. The bitch exhibited progressive muscle weakness and was euthanized due to severe clinical illness. In necropsy markedly enlarged heart and dilated esophagus were present. At the light microscopic level there was accumulation of PAS‐positive material in the cytoplasm and vacuolar degeneration of myocytes within the heart, skeletal muscle and esophagus. Electron microscopy (EM) and measurement of the enzyme activity of the acid α‐glucosidase in blood leucocytes were performed. Further characterization of the cellular pathology is currently under investigation.