Thromboelastographic changes after gonadectomy in retired racing greyhounds

Abstract

Twenty-one healthy greyhounds with no history or clinical signs of bleeding disorders, and no abnormalities on physical examination, complete blood count, serum biochemistry profiles (in dogs more than five years of age), and SNAP-4DX test for vector borne diseases underwent routine gonadectomies at the Ohio State University Veterinary Teaching Hospital. Blood samples were collected 24 hours before and after surgery by jugular venepuncture for thromboelastography and haemostasis assays (prothrombin time [PT], activated partial thromboplastin time [aPTT], fibrinogen concentration). The magnitude of the bleeding in each patient was estimated using a bleeding scoring system recently validated in greyhounds. Eight dogs were classified as bleeders and 13 as non-bleeders. Thromboelastograph (TEG) tracings in bleeders were different to that of non-bleeders. Neither sex (odds ratio [OR]: 0.148, P=0.05), haematocrit (OR: 0.907, P=0.39), platelet count (OR: 0.996, P=0.65) or age (OR: 0.949, P=0.83) were predictors of the outcome. None of the variables that evaluated clot kinetics, and fibrinolysis (that is, aPTT OR: 0.781, P=0.51; PT OR: 1.337, P=0.63; TEGR OR: 1.269, P=0.06; TEGK OR: 1.696, P=0.05; TEGLY60 OR: 1.028, P=0.81) were able to predict the bleeding episodes. Only the TEG variables that represent the fibrin cross-linking of the clot (TEGangle OR: 0.903, P=0.03); and the strength of the clot (TEGMA OR: 0.833, P=0.03) were considered predictors of the outcome.

Assessment of coagulation utilizing thromboelastometry in dogs undergoing orthopedic surgery

“…The α angle has similar behavior and a similar explanation to the increased MCF; it significantly increased from T0 to T2 in the in‐TEM assay and in the ex‐TEM assay. These findings are similar to those reported by Vilar Saavedra and others, who demonstrated that TEG parameters representing fibrin cross‐linking (α angle) and clot strength (maximum amplitude) increase after gonadectomy in retired racing Greyhounds . In human patients undergoing a wide variety of surgical procedures, the risk of deep venous thrombosis was significantly higher in patients with a TEG maximum amplitude >68 mm, establishing a putative cutoff to assess the risk for the development of this complication …”

“…In brief, the MCF of the fib‐TEM assay (which is related to the functional fibrinogen concentration) was the only variable to significantly increase for each comparison. The changes observed in MCF are likely related to postoperative increases in fibrinogen concentration, a consistent postoperative finding in people . The α angle has similar behavior and a similar explanation to the increased MCF; it significantly increased from T0 to T2 in the in‐TEM assay and in the ex‐TEM assay.…”

“…TEM and platelet count b were performed at 3 time points: 1 hour before the surgery (T0), 24 hours after the conclusion of the surgery (T1), and 7 days after surgery (T2). These time points were chosen based on previous studies in dogs and people . Blood specimens were collected by jugular venipuncture with a 20‐Ga needle by exerting short duration occlusion of the vessel.…”

Thromboelastographic Evaluation of Dogs with Acute Liver Disease

“…In 1 study, the G value calculated from tissue factor‐activated TEG had a positive predictive value of 89% and a negative predictive value of 98% in identifying bleeding tendencies . In a separate study limited to greyhounds, MA, angle, and G predicted postoperative bleeding tendencies . Lastly, in a recent study, TEG was reliable in identifying thrombocytopenic dogs to be at a low risk of bleeding .…”

Platelet closure time in anesthetized Greyhounds with hemorrhagic shock treated with hydroxyethyl starch 130/0.4 or 0.9% sodium chloride infusions

“…In addition, they are known to have a higher PCV, resulting in higher blood viscosity, and a lower platelet count . Some Greyhounds are also known to have significant postoperative bleeding, which may be related to increased fibrinolysis or reduced fibrin cross‐link formation and clot strength . Despite postoperative bleeding, PCTs were found to be normal in one study .…”