Platelet and fibrinogen kinetics in canine tumors.

Fifty-three dogs with spontaneously occurring tumors were evaluated for abnormalities in the concentration and in vivo survival of platelets and fibrinogen. Thrombocytopenia occurred only in animals with extensive tumor involving spleen or marrow. Platelet survival was shortened in 6 of 15 (40%) dogs with localized tumor [mean 4.4 days +/- 0.3 (S.E.); normal 5.4 days +/- 0.1] and 30 of 35 (80%) dogs with metastatic tumor (mean 3.2 days +/- 0.2). Platelet survival progressively shortened during studies performed in dogs with ongoing disease. Fibrinogen concentration was increased (mean 420 +/- 30 mg/dl) in 44 of 53 (83%) of tumor-bearing dogs (normal 210 +/- 10 mg/dl). Neither history nor extent of disease, including presence of hepatic metastases, appeared to influence fibrinogen concentration significantly. Fibrinogen survival was below the normal range in 3 of 15 (20%) dogs with localized tumor and in 9 of 34 (26%) dogs with metastatic tumors. Thus, platelet consumption appeared to be the most significant hemostatic abnormality in tumor-bearing dogs. This model may be useful in evaluating the efficiency of antithrombotic therapy in preventing tumor-related hemostatic abnormalities.