Test Detail

Molecular test for hereditary thrombocytopathy of the Basset Hound and the Landseer, a platelet function disorder due to a signalling/aggregation defect that produces a bleeding phenotype with a normal platelet count. It affects the haematological/haemostatic system and makes premedication necessary for surgeries and wounds. The test reports clear/carrier/affected status for the corresponding variant.

Applicable breeds: Basset Hound and Landseer. Carrier frequencies are not published systematically (limited data); the clinical case series is well documented in the Basset Hound.

- Mucocutaneous bleeding tendency: epistaxis, gingivorrhagia\n- Petechiae and ecchymoses, spontaneous or after minimal trauma\n- Prolonged post-surgical or post-traumatic bleeding\n- Normal platelet count with prolonged bleeding time\n- Normal primary coagulation (normal PT/PTT)

Hereditary thrombocytopathy was described in the Basset Hound (Catalfamo et al. 1986) and later in the Landseer, as a platelet function defect with a normal count. Molecular characterisation identified mutations in the RASGRP2 gene (CalDAG-GEFI), involved in platelet aggregation signalling, with different variants in the Basset Hound and the Landseer (Boudreaux et al. 2007).

- Genotype breeding animals before mating\n- Do not cross carrier×carrier (25 % risk of affected homozygotes); carrier×clear produces 0 % affected and 50 % carriers\n- An affected animal must not be bred; a carrier can be crossed with a clear dog without producing affected offspring\n- After a confirmed clinical case, do not repeat the parental mating and inform the buyer of the status

Confirmation by complete blood count (normal platelet count), prolonged bleeding time and platelet aggregometry (abnormal aggregation pattern). Differentiate from Glanzmann thrombasthenia (GPIIb/IIIa defect, total absence of aggregation) and from von Willebrand disease. Management: avoid NSAIDs and anticoagulants; platelet or plasma transfusion in active bleeding; haematological assessment before surgery.

1. Boudreaux MK, Catalfamo JL, Klok M. (2007) Calcium-diacylglycerol guanine nucleotide exchange factor I gene mutations associated with loss of function in canine platelets. Transl Res 150:81-92. PMID: 17656327
2. Catalfamo JL, Raymond SL, White JG, Dodds WJ. (1986) Defective platelet-fibrinogen interaction in hereditary canine thrombopathia. Blood 67:1568-1577. PMID: 3011147
3. Christopherson PW, Alexander EA, King KB, Boudreaux MK. (2016) Basset Hound thrombopathia in a 4-month-old female Ba-Shar (Sharp Asset). Vet Clin Pathol 45:229-231. PMID: 27037855