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Lethal primary immunodeficiency characterised by functional absence of T and B lymphocytes due to failure of V(D)J recombination. Affected puppies do not develop adaptive immunity and die from opportunistic infections in the first months of life. The autosomal recessive form is recognised in terriers and related breeds, distinct from X-linked X-SCID of the Basset Hound and the Pembroke Welsh Corgi.

The Jack Russell Terrier is the best-characterised breed for autosomal SCID due to PRKDC (OMIA000220-9615). In related breeds (Parson Russell Terrier) the molecular evidence is more limited. The Frisian Water Dog (Wetterhoun) has autosomal SCID due to RAG1, not PRKDC.

- Failure to thrive, diarrhoea and recurrent pneumonia in nursing puppies\n- Hypoplastic lymph nodes\n- Opportunistic respiratory and digestive infections\n- Death usually before 4 months of age without treatment

Canine SCID was first described in the Basset Hound (X-linked form) and later in the Jack Russell Terrier as an autosomal entity with a defect in the catalytic subunit of DNA-PK encoded by PRKDC. Studies by the Henthorn and Felsburg groups characterised the V(D)J recombination failure in these animals. The Parson Russell Terrier, a related breed, carries the same mutation. Specific information on the Frisian Water Dog (Wetterhoun) is more limited.

- Genotype breeding animals from affected lines before mating\n- Do not cross two carriers: 25 % risk of affected homozygotes\n- A carrier can be crossed with a clear dog; offspring intended for breeding must be tested\n- Identify carriers in lines with a family history\n- Exclude affected animals from breeding

Differential diagnosis with the X-linked form (X-SCID, IL2RG) of the Basset Hound and the Pembroke Welsh Corgi. Bone marrow transplantation is the only curative option; without treatment, lethality is early.

1. Meek K et al. (2001) SCID in Jack Russell terriers: a new animal model of DNA-PKcs deficiency. J Immunol 167:2058-2065. PMID: 11489998
2. Ding Q et al. (2002) DNA-PKcs mutations in dogs and horses: allele frequency and association with neoplasia. Gene 283:123-129. PMID: 11867233
3. Verfuurden B et al. (2011) Severe combined immunodeficiency in Frisian Water Dogs caused by a RAG1 mutation. Genes Immun 12:303-307. PMID: 21293384
4. OMIA:000220-9615 (PRKDC, Jack Russell Terrier) y OMIA:001574-9615 (RAG1, Frisian Water Dog).