Hereditary thrombopathy due to CalDAG-GEFI (RASGRP2) deficiency, with markedly altered platelet aggregation. Three breed-specific mutations have been described: American Eskimo Dog (duplication), Basset Hound (three-base deletion) and Landseer (nonsense mutation). Affected dogs show mucocutaneous bleeding with normal platelet count and coagulation tests.

Each variant is documented in its breed (American Eskimo Dog, Basset Hound, Landseer; Boudreaux et al. 2007); no published population frequency figures.

- Epistaxis\n- Gingival haemorrhage\n- Petechiae and ecchymoses\n- Prolonged bleeding time\n- Normal platelet count and coagulation\n- Markedly reduced platelet aggregation in response to ADP, collagen and PAF

Boudreaux, Catalfamo and Klok (2007) identified the mutations in the CalDAG-GEFI gene (RASGRP2) in three dog breeds. Platelet defects had previously been described in the Basset Hound and in Spitz dogs.

- Test breeding animals of the affected breeds before mating\n- Autosomal recessive inheritance: do not use affected homozygotes as breeding animals\n- Do not cross two carriers (25 % homozygotes per litter)\n- A carrier can be crossed with a clear animal; test the offspring intended for breeding\n- Record the status in the pedigree

Differential diagnosis with von Willebrand disease and other platelet defects. The molecular test identifies carriers; functional confirmation (aggregometry, bleeding time) remains useful. Do not confuse with the CalDAG-GEFI mutations described in ruminants.

Boudreaux MK et al. 2007. Calcium-diacylglycerol guanine nucleotide exchange factor I gene mutations associated with loss of function in canine platelets. Transl Res. PMID: 17656327