Metabolic Enzyme Deficiency in Cats

Lysosomal Storage Diseases in Cats

Lysosomal storage diseases are primarily genetic in cats and are caused by a lack of the enzymes that are needed to perform metabolic functions. It is a rare disease that most commonly is diagnosed in kittens. The disease causes an accumulation of various substances that would otherwise be eliminated by the enzymes, and which become stored in the cat’s tissues in abnormal amounts (usually occurring in the nervous system). As a result, cells swell and can no longer function normally. Unfortunately, lysosomal storage diseases are always fatal.

The following breeds are most likely to have the disease:

• Persian
• Siamese
• Korat
• Domestic shorthair
• Balinese

Symptoms and Types of Lysosomal Storage Diseases

Affected animals are usually born normal but develop symptoms within the first few months of life. Symptoms vary depending on the severity of the enzyme deficiency but may include:

• Failure to thrive
• Balance problems
• Exercise intolerance
• Inconsistent behavior
• Compromised vision
• Fainting
• Seizures

Diagnosis of Lysosomal Storage Diseases

If your cat has these symptoms and is one of the previously listed breeds, your veterinarian will want to know your cat’s history so that an initial diagnosis can be made. The following tests are likely to be performed to confirm the diagnosis:

• Complete blood count
• Biochemical profile
• Urinalysis
• X-rays of chest and abdominal area
• Ultrasound of abdomen
• Biopsy of tissue
• Enzyme measure 

Treatment for Lysosomal Storage Diseases

If the cat is weak and dehydrated, an IV will be inserted and fluids and electrolytes will be administered. A dietary plan will be also be arranged to ward off hypoglycemia (low blood sugar). Activity must be limited. Your cat will need to be restricted to a safe area where it cannot become injured, preferably a comfortable carrier or small confined area. Careful monitoring is required because there is a high risk of developing secondary infections.

Living and Management of Lysosomal Storage Diseases

Restrict activity and be alert to the cat's symptoms. In addition, maintain the prescribed nutritional plan. Blood sugar, growth, and hydration status must be monitored regularly. This disease is progressive, and unfortunately, it is ultimately fatal.

Remember that the disease is genetic and inbreeding should be carefully avoided when there is a defective gene anywhere in the family. Cats that have been diagnosed with the disease should also never be mated.