HEMOSTATIC ABNORMALITIES IN DOGS SUFFERIN G FROM ACUTE LYMPHOBLASTIC-LEUKEMIA

Twelve dogs suffering from acute lymphoblastic leukaemia were investig ated concerning the following tests: platelet count, prothrombin time (PT, standard test, modified test), activated partial thromboplastin t ime (APTT), activity of the individual coagulation factors IT, V, VII, X, VIII:C, IX, XI, XII, prekallikrein,, and high-molecular weight kin inogen, the activity of antithrombin III (AT III), protein C, plasmino gen, and alpha(2)-antiplasmin as well as concentration of fibrinogen, soluble fibrin and fibrin(ogen) degradation products (FDP). All patien ts showed a decreased platelet count due to suppression of megakaryopo esis by infiltration of the bone marrow with leukaemic cells. In addit ion, in most of the patients a moderate activity decrease of one or mo re individual coagulation factors has been found, especially regarding factor II (median, x(0.50) = 51%, p 0.0001), but also factors X (x(0. 50) = 71%, p = 0.0003) and XI (x(0.50) = 68%), p = 0.0006). This was r eflected by the APTT and the PT activity (modified test), which were p rolonged or decreased, respectively, in the majority of the cases. Fur thermore, the activity of AT III and of plasminogen was distinctly dim inished (p < 0.001). Like the concentration of FDP, the plasma level o f soluble fibrin was significantly higher than in normal dogs (p < 0.0 01). This indicates that besides thrombocytopenia disseminated intrava scular coagulation occurs frequently in dogs with acute lymphoblastic leukaemia and is a main cause for the decreased activity of several pl asmatic components of the haemostatic system. The lack of correlation between the concentration of soluble fibrin as an indicator of intrava scular coagulation and the total blast cell count (r(S) = 0.011) shows the importance of other factors like degree of cell lysis as well as participation of organs such as the liver for generation of consumptio n coagulopathy in dogs with acute lymphoblastic leukaemia.