Exercise Intolerance of a Catalan Sheepdog

A 5-year-old male neutered Gos d'atura catala was referred to the Utrecht University Clinic for Companion Animals for evaluation of progressive exercise intolerance since 2 months, weight loss, polyphagia and tachypnoe. He had always been a very quiet dog and never was very energetic.

At presentation he had a stiff gait in the front limbs and could only walk for a few meters before he had to lie down. He presented with a breathing frequency of 80/min and showed no further abnormalities on clinical examination.

During the workup of exercise intolerance elevated muscle and liver enzymes, elevated lactate, hypoglycemia and myoglobinuria were detected. A storage disease was suspected and liver and muscle biopsies were taken. Glycogen storage was identified in the liver biopsies whereas lipid storage was diagnosed in the muscle biopsies

Canine lipid storage myopathies are usually associated with primary or secondary carnitine deficiency, abnormal function of mitochondria or deranged fatty acid oxidation.

Glycogen storage diseases are rare diseases in dogs.

In humans different glycogen storage diseases are recognized. Storage diseases as a cause of myopathies are also rare. In human literature there are a few reports in which glycogen storage disease with concurrent muscular lipid storage or glycogen storage and carnitine deficiency are described. How the two storage problems are connected is not completely understood.

The dog was supplemented with L-carnitine, coenzyme Q, Riboflavin and fed with a high protein diet with multiple portions divided over the day. The dog improved clinically.
If a muscular and hepatic storage disease is suspected, it is important to take biopsies of both the liver and the muscles, because the storage products can differ. In human medicine it has been documented that patients only improve clinically when both problems are treated.