General Veterinary Pathology

GLYCOGEN STORAGE DISEASES (GLYCOGENOSES)

• The cells may accumulate abnormal amount of glycogen in the cytoplasm. The cells are swollen with foamy cytoplasm. The condition is not common in animals. It may be associated with prolonged hyperglycaemia and there may be lack of enzymes that metabolize carbohydrates. It is a group of disease in which two forms are recognized in animals.
• Type II or Pompe’s disease: There is deficiency of lysosomal α-glucosidase with accumulation of glycogen in the lysosome of brain, muscle and liver. This condition is seen in cattle, dogs, cats and sheep.
• Type III or Cori-Forbes' disease: There is deficiency of amylo-1,6-glucosidase which converts glycogen to glucose. Hence, glycogen is stored in the cytoplasm of liver, heart, skeletal and smooth muscle and nerve cells. This condition is reported in dogs and cats.
• Type Ia (von Gierke disease in humans): There is deficiency of glucose-6-phosphatase that catalyses hydrolysis of glucose-6-phosphate to glucose and phosphate. Affected pups show tremors, weakness and neurological signs due to hypoglycaemia and growth retardation and progressive hepatomegaly is found as they develop. Massively enlarged hepatocytes show vacuolations with aggregation of glycogen rosettes,