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Mucopolysaccharidosis Type IIIA (Discovered in the Dachshund)

Mucopolysaccharidosis Type IIIA (MSP IIIA) is a disease of progressive incoordination, first in the pelvic legs and later progressing to all four legs. Leg movements become erratic when walking and affected dogs have difficulty balancing.

Key Signs

Pelvic limb ataxia, Severe generalized spinocerebellar ataxia, Hypermetria, Exaggerated reflexes

Age of Onset

1 to 4 yrs

Junior to adult onset


Autosomal Recessive

For autosomal recessive disorders, dogs with two copies of the variant are at risk of developing the condition. Dogs with one copy of the variant are considered carriers and are usually not at risk of developing the disorder. However, carriers of some complex variants grouped in this category may be associated with a low risk of developing the disorder. Individuals with one or two copies may pass the disorder-associated variant to their puppies if bred.

Likelihood of the Condition

High likelihood

At risk dogs are highly likely to show signs of this disease in their lifetime.

What to Do

Here’s how to care for a dog with MPS IIIA

Partner with your veterinarian to make a plan regarding your dog’s well-being, including any insights provided through genetic testing. If your pet is at risk or is showing signs of this disorder, then the first step is to speak with your veterinarian.

For Veterinarians

Here’s what a vet needs to know about MPS IIIA

Mucopolysaccharidosis type IIIA is characterized by progressive ataxia (uncoordinated movements), and first clinical signs are usually observed in the third year of life. The signs of ataxia are initially seen in pelvic limbs progressing later to all four limbs. The clinical signs include dysmetric gait and loss of balance. An affected dog may also sway while standing.

This disorder is progressive with no cure. Wellbeing of affected dogs should be monitored. Owners should be advised that as clinical signs progress, affected dogs may have difficulties on smooth surfaces and with climbing stairs. Euthanasia is often elected on welfare grounds when clinical signs become severe.

For Breeders

Planning to breed a dog with this genetic variant?

There are many responsibilities to consider when breeding dogs. Regardless of test results it is important that your dog is in good general health and that you are in a position to care for the puppies if new responsible owners are not found. For first time or novice breeders, advice can be found at most kennel club websites.

This disease is autosomal recessive meaning that two copies of the mutation are needed for disease signs to occur. A carrier dog with one copy of the MPS IIIA mutation can be safely bred with a clear dog with no copies of the MPS IIIA mutation. About half of the puppies will have one copy (carriers) and half will have no copies of the MPS IIIA mutation. Puppies in a litter which is expected to contain carriers should be tested prior to breeding. Carrier to carrier matings are not advised as the resulting litter may contain affected puppies. Please note: It is possible that disease signs similar to the ones caused by the MPS IIIA mutation could develop due to a different genetic or clinical cause.

Technical Details

Variant C>A
Chromosome 9
Coordinate Start 1,544,373
Coordinate End 1,544,375

All coordinates reference CanFam3.1

References & Credit

Credit to our scientific colleagues:

Aronovich, E. L., Carmichael, K. P., Morizono, H., Koutlas, I. G., Deanching, M., Hoganson, G., … Whitley, C. B. (2000). Canine heparan sulfate sulfamidase and the molecular pathology underlying Sanfilippo syndrome type A in Dachshunds. Genomics, 68(1), 80–84. View the article