Biochemical Basis for the Hypercoagulable State Seen in Cushing Syndrome

HYPOTHESIS Cushing syndrome (CS) is associated with a hypercoagulable state that results in a 4-fold increase in the incidence of pulmonary embolism, deep venous thrombosis, and a 4-fold mortality rate compared with the general population. The incidence of CS in humans is approximately 2 to 5 per million per year, whereas in dogs it is much higher. The clinical complications of CS in humans are also manifested in dogs. We used a dog model of CS to better define the biochemical basis for the hypercoagulable state seen in the disease. DESIGN A consecutive sample of dogs with CS and a cohort of healthy control dogs identified at a "well-dog check" were enrolled. All dogs underwent blood assays to identify the levels of procoagulant factors, natural antithrombotics, and the degree of ongoing activation of the coagulation cascade. SETTING University veterinary medical teaching hospital. RESULTS A total of 86 dogs were enrolled, 56 with CS and 30 control dogs. Levels of procoagulation factors II, V, VII, IX, X, XII, and fibrinogen were significantly increased in dogs with CS (P