Hemophilia A in a Male Parson Russell terrier puppy

Hemophilia A (HA) is the most common inherited bleeding disorder in dogs. It is sex-linked, and has been described in many breeds. This report describes the clinical course and the diagnosis of HA in a 7-month old Parson Russell Terrier puppy, which was presented due to repeated bleeding episodes. The diagnostic tests included complete blood counts, prothrombin time (PT), activated partial thromboplastin time (aPTT), buccal mucosal bleeding time (BMBT), thromboelstometry using a surface contact activator (INTEM) and tissue factor (EXTEM) and determination of activities of factors VIII, IX and XI. The platelet counts, BMBT, PT and EXTEM were within reference intervals. The activities of factors VIII, IX and XI were 0.97%, 71.0% and 84.4%, respectively, compared to their average activities in the samples of two healthy dogs. Testing also ruled out the presence of coagulation inhibitors. The results confirmed a diagnosis of inherited HA, with severe factor VIII:C deficiency (<1% compared to reference plasmas). The aPTT, measured both by coagulometric analyzers and a fibrometer were prolonged (1.05- to 2.3-fold the upper reference limits [URL]), as was the INTEM clotting time (2.3-fold the URL), and did not reflect the severity of the deficiency. The dog was treated with oral tranexamic acid, which failed to prevent repeating bleeding episodes, and was therefore euthanized at his owners’ request. This is the first report of HA in a Parson Russell Terrier in Israel, and the first report in which thromboelastomtry was also utilized as a diagnostic test in HA in dogs.