Lysosomal Storage Diseases in Dogs

What are lysosomal storage diseases?

Lysosomal storage diseases are a group of disorders that occur when the body does not make certain metabolic enzymes that lysosomes need to break down materials in cells.

Lysosomes are “recycling centers” in the cells, and they use these enzymes to break down worn-out materials into substances the cells can reuse. If a specific enzyme is absent, the material it would normally break down begins to accumulate, or become “stored,” inside the cells. This buildup can damage tissues and eventually cause organ system failure.

What causes lysosomal storage diseases?

Lysosomal storage diseases are rare and are inherited through recessive genes, which means that both parents must carry a gene for the disease and both must pass it to their offspring for the disease to appear. Responsible breeders remove these dogs from their breeding programs.

What are the clinical signs of lysosomal storage diseases?

The clinical signs of lysosomal storage diseases vary depending on the enzyme missing, the cells involved, and the material that is accumulating. In general, the most common symptoms in puppies with lysosomal storage diseases include:

• Failure to thrive
• Incoordination and balance issues
• Exercise intolerance
• Abnormal vision or progression to blindness
• Fainting
• Seizures

What are some examples of lysosomal storage diseases in dogs?

Several lysosomal storage diseases occur in dogs. Each has different effects and tends to affect specific breeds. These diseases include:

Ceroid lipofuscinosis 

Dogs with ceroid lipofuscinosis lack the enzyme that breaks down a type of fat that otherwise accumulates in nerve cells and in the liver, kidneys, and spleen. Associated signs include decreased vision, head tilt, dilated pupils, lameness, dementia, seizures, and balance problems. Breeds most often affected include the Border Collie, Chihuahua, Cocker Spaniel, Dachshund, English Setter, Golden Retriever, and Saluki. Prognosis is poor, and many dogs are euthanized shortly after diagnosis.

Gangliosidosis 

Dogs with gangliosidosis lack the enzyme that breaks down a molecule on the surface of the brain and neural cells. Clinical signs include decreased vision, nystagmus (twitching of the eyes), lethargy, weakness, dementia, tremors, incoordination, seizures, and a stiff gait. Breeds most often affected include the Beagle, English Springer Spaniel, German Shorthaired Pointer, Japanese Chin, Portuguese Water Dog, Shiba Inu, Siberian Husky, and Toy Poodle. Prognosis is very poor, and most dogs are euthanized before one year of age.

Globoid cell leukodystrophy (GCL)

Dogs with GCL, also known as Krabbe's disease, lack an enzyme that breaks down a type of fat that affects nerve impulse transmission. Associated symptoms include decreased vision, tremors, incoordination, seizures, muscle atrophy, deafness, and partial paralysis. Breeds most often affected include the West Highland White Terrier, Cairn Terrier, and Irish Setter. Prognosis is very poor, and most dogs are euthanized before one year of age.

Mucopolysaccharidosis 

Dogs with mucopolysaccharidosis lack the enzyme that breaks down one of the building blocks of cartilage, bone, tendon, skin, connective tissues, and the corneas. Clinical signs include weakness that starts in the rear legs and progresses to all four limbs, muscle-bone disproportion, and clouded corneas. Commonly affected breeds include the Rottweiler, Boston Terrier, Retrievers (Chesapeake Bay, Labrador, and Golden), German Shepherd, Miniature Pinscher, and Plott Hound. Prognosis is poor, and many dogs don't make it to adulthood.

Pyruvate kinase deficiency 

Dogs with pyruvate kinase deficiency lack the enzyme that involves the metabolism of red blood cells. Clinical signs include anemia, weakness, muscle wasting, jaundice (yellowish mucous membranes), and elevated heart rate. Commonly affected breeds include the Basenji, Beagle, Cairn Terrier, Dachshund, Pug, and West Highland White Terrier. Prognosis is guarded (uncertain) and seems to vary depending on the breed. Some dogs live for a few years before succumbing to disease.

Is there any treatment for lysosomal storage diseases?

Unfortunately, lysosomal storage diseases are fatal. The disorders manifest shortly after birth, progress rapidly, and the affected dogs typically die between four and six months of age. The missing enzymes are involved in basic metabolic functions, and without them, the body cannot function and thrive.