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Severe Combined Immunodeficiency (Discovered in Frisian Water Dogs)

Severe Combined Immunodeficiency (SCID) is a dysfunction of the immune system, that leaves affected dogs prone to infection.

Key Signs

Poor growth, Diarrhea, Vomiting, Seizures, Ataxia, Blindness, Depletion of lymphoid tissues, Reduced level of immunoglobulin, Reduced levels of lymphocytes

Age of Onset

0 to 2 yrs

Juvenile 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 SCID

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 SCID

Severe combined immunodeficiency is characterized by T- and B-lymphocyte dysfunction resulting in a non-functional immune system. Affected dogs are predisposed to infections. The onset of signs typically occurs at 7 to 8 weeks of age and includes lethargy, poor growth, vomiting, diarrhea, ataxia, seizures, and blindness. Affected dogs rarely survive over 4 months of age. There is no treatment available for SCID.

Therapy is limited to symptomatic treatments for resulting infections and general supportive care. There is no cure.

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 SCID mutation can be safely bred with a clear dog with no copies of the SCID mutation. About half of the puppies will have one copy (carriers) and half will have no copies of the SCID 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 SCID mutation could develop due to a different genetic or clinical cause.

Technical Details

Gene RAG1
Variant G>T
Chromosome 18
Coordinate 31,631,772

All coordinates reference CanFam3.1

References & Credit

Credit to our scientific colleagues:

Verfuurden, B., Wempe, F., Reinink, P., Van Kooten, P. J. S., Martens, E., Gerritsen, R., … Leegwater, P. A. (2011). Severe combined immunodeficiency in Frisian Water Dogs caused by a RAG1 mutation. Genes and Immunity, 12(4), 310–313. View the article