Print

Metabolic Disorders Due to Lysomal Enzyme Deficiency in Dogs

Mucopolysaccharidoses are a group of metabolic disorders characterized by the accumulation of GAGs (glycosaminoglycans, or mucopolysaccharides) due to the impaired functions of lysosomal enzymes. It is the mucopolysaccharides which help in building bones, cartilage, skin, tendons, corneas, and the fluid responsible for lubricating joints.

Plott hounds, Labrador retrievers, wire-haired dachunds, Huntaway (sheep) dogs, miniature pinschers, miniature schnauzers, Welsh corgis, mixed breeds, and German shepherds are predisposed to mucopolysaccharidoses.

Symptoms and Types

Symptoms and signs depend upon the type of enzyme deficiency, type of GAG stored, and the tissue in which storage occurs. Some of the more common ones include:

• Dwarfism
• Severe bone disease
• Degenerative joint disease (DJD), including partial dislocation of hip joint
• Facial structural deformity
• Enlarged liver
• Enlarged tongue
• Eye cloudiness

Causes

Mucopolysaccharidoses is a genetic abnormality. However, inbreeding increases the risk, especially if the defective gene is present in the family.

Diagnosis

You will need to give a thorough history of your dog’s health, including the onset and nature of the symptoms, to your veterinarian. He or she will then perform a complete physical examination, as well a biochemistry profile, urinalysis, and complete blood count (CBC). These tests may reveal valuable information for initial diagnosis, including the presence of characteristic granules within neutrophils and monocytes (types of white blood cells). Your pet’s veterinarian will also take a sample from other body sites and organs -- such as the liver, bone marrow, joints, and lymph nodes -- for further analysis.

Definitive diagnosis, however, is typically made by measuring the lysosomal enzyme levels in blood or liver. Bone X-rays, meanwhile, will reveal decreased bone density and other bone- and joint-related abnormalities.