Severe Combined Immunodeficiency (SCID) is an inherited condition that affects a dog’s ability to fight infection. These dogs are not able to produce a protein important for proper immune function which predisposes them to severe and recurring bacterial, viral and fungal infections. Symptoms of the disease typically present around 12 to 14 weeks of age and can include active infections of the skin, eye or ear. Additional symptoms can include poor growth, lethargy, failure to thrive, weight loss, diarrhea and vomiting. Pathology testing will typically show very low white blood cell count and low or no IgM antibodies in serum. Affected dogs will typically die by 4 months of age due to recurring infection.

• Jack Russell Terrier

A (CLEAR/NORMAL): These dogs have two copies of the normal gene and will neither develop severe combined immunodeficiency nor pass this mutation to their offspring.

B (CARRIER/NOT AFFECTED): These dogs have one copy of the normal gene and one copy of the mutation associated with this disease. They will not develop severe combined immunodeficiency but will, if bred, pass the mutation to 50% of its offspring, on average.

C (AT RISK/AFFECTED): These dogs have two copies of the mutation associated with this disease and will likely develop severe combined immunodeficiency.