Blood clotting changes in dogs with untreated and treated Cushing's

Abstract

OBJECTIVE: To determine whether or not there are differences in coagulation parameters (eg, thrombelastography [TEG], activated partial thromboplastin time [aPTT], prothrombin time [PT], and fibrinogen) among dogs with naturally occurring hyperadrenocorticism (HAC), dogs with HAC undergoing medical management, and dogs without HAC. DESIGN: Prospective, observational study. SETTING: Veterinary teaching hospital. ANIMALS: Forty-six client-owned dogs undergoing adrenal function testing. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Nine dogs were diagnosed with HAC de novo, 19 dogs were presented for therapeutic monitoring of previously diagnosed HAC, and 18 dogs did not have HAC. Variables compared between groups were age, body weight, platelet count, mean platelet volume, serum concentrations of cholesterol, triglycerides, antithrombin, PT, aPTT, fibrinogen, and TEG parameters (eg, alpha angle, R, K, and maximum amplitude [MA]). Dogs with HAC and dogs treated for HAC had higher serum cholesterol than dogs without HAC (P < 0.05). All groups had mean MA greater than the institutional reference interval. There was a weak, positive correlation between hematocrit and MA that was independent of diagnosis (r(2) = 0.266, P = 0.004). CONCLUSIONS: The results of this study do not support the supposition that a significant difference exists in coagulation tendencies between dogs with HAC prior to treatment, dogs with HAC during treatment, and dogs without HAC. This disagreement with the classically accepted notion that HAC leads to a hypercoagulable state could be due to a couple of possibilities. Namely, the link between HAC and hypercoagulability may be relatively weak, or our findings may be the result of a type II error either as a result of a small sample size or the use of coagulation assays that are insensitive to the effects of HAC on the hemostatic system.