Glycogenosis in Cats (Type IV)
Glycogen storage disease, also known as glycogenosis, is a rare inherited disorder with various types, all characterized by deficient or defective activity of the enzymes responsible for metabolizing glycogen in the body. This leads to an abnormal accumulation of glycogen, the main carbohydrate storage material in the body which aids short term energy storage in cells by converting to glucose as the body needs it for metabolic requirements. Accumulation of glycogen in the tissues can result in the enlargement and dysfunction of various organs, including the liver, heart, and kidneys.
The Type IV classification found in cats is seen in the Norwegian Forest breed. Signs may manifest at five to seven months of age, or in some cases, the disease may manifest in the womb, resulting in a still birth.
SYMPTOMS AND TYPES
In cats, type IV glycogen storage disease is apparent in Norwegian Forest cats, and often results in death before birth. If your cat survives this condition, symptoms can include fever, muscle tremors, and weakness.
The various forms of glycogenoses all result from some sort of deficiency in glucose-metabolizing enzymes in the body. The types are distinguished by the specificenzymedeficiency. Type IV, the type found in cats, results from a deficiency of the glycogen branching enzyme.
Diagnostic procedures will vary depending on the symptoms and suspected type of glycogen storage disease at hand. A tissue enzyme analysis and determination of glycogen levels can serve as a definitive diagnosis. Other tests may include urine analysis, genetic testing, and electrocardiography (ECG) to check the electrical output from the heart for changes.
Care will vary depending on the type of glycogen storage disease diagnosed and the severity of symptoms. Hypoglycemia may need to be regulated with diet, feeding frequent portions of a high-carbohydrate diet.
LIVING AND MANAGEMENT
Upon diagnosis, your cat will need to be continuously monitored and treated, if necessary, for hypoglycemia. However, there is not much that can be done. Glycogenosis is fatal for most animals, or they are euthanized due to progressive physical deterioration.
Because this is an inherited disease, animals that develop glycogen storage disease should not be bred, nor should their parents breed again, in order to avoid the possibility of future cases.