Bo Wiinberg

Haemostatic alterations are commonly detected in human and canine cancer patients. Previous studies have described haemostatic dysfunction in canine patients with haemangiosarcomas and carcinomas, and haemostasis has been assessed in dogs with various malignant and benign neoplasias. Few studies have addressed the effect of cancer type and progression of disease on the presence of haemostatic alterations in canine patients. The objective of the present study was to evaluate haemostatic variables of coagulation and fibrinolysis in a group of canine cancer patients, and to compare haemostatic changes to the cancer type and progression of disease.

Thromboelastography (TEG) has been used in experimental animal studies since the early 1960s and in a routine clinical setting for the past decade. From the data currently available, it is clear that both the scope and limitations of TEG in animals resemble those observed in humans. TEG has been used to diagnose hypercoagulability in animals with disseminated intravascular coagulation, various types of cancer, and critical illness. Its ability to detect and monitor animals with various types of coagulopathies has been well established, both clinically and in experimental studies. TEG is often used in animals to monitor the effect of different pro- and anticoagulant drugs and often performs better at this task than conventional coagulation assays. TEG is already well established in veterinary medicine, and with the rapid dissemination of the technique currently taking place, we can expect to see a wide variety of interesting animal data published in the near future.

During the last decade, thromboelastography (TEG) has gained increasing acceptance as a diagnostic test in veterinary medicine for evaluation of haemostasis in dogs, however the use of TEG in cats has to date only been described in one previous study and a few abstracts. The objective of the present study was to evaluate and compare three different TEG assays in healthy cats, in order to establish which assay may be best suited for TEG analyses in cats.

Background: There is considerable variation in the coagulation profile of dogs with disseminated intravascular coagulation (DIC), making it difficult to assess overall hemostatic function. Objectives: To characterize the overall hemostatic state in dogs with DIC, by use of tissue factor-activated thromboelastography (TF-TEG), and to determine whether there is an association between hemostasis and outcome. Animals: 50 dogs with DIC. Methods: Dogs admitted to the intensive care units, with an underlying disease known to predispose to DIC, were prospectively assessed with TF-TEG. Citrated blood samples were collected daily during hospitalization and an extended coagulation panel and TF-TEG were performed. Diagnosis of DIC was based on expert opinion. Results: Hemostatic dysfunction was observed on the TF-TEG profile in 33/50 of the dogs, of which 22/50 were hypercoagulable and 11/50 were hypocoagulable based on the TF-TEG G value alone. There were significant differences in k, α, and MA values (P < .0001) among hypo-, normo-, and hypercoagulable dogs. There was a significant difference in case fatality rate between hypo- (64%) and hypercoagulable (32%) dogs (relative risk = 2.38; P= .04). Dogs that died had significantly lower antithrombin activity (P= .03) and higher d-dimer concentration (P= .03) than survivors. Conclusions: The most common overall hemostatic abnormality in dogs diagnosed with DIC was hypercoagulability, and there was significant difference in survival between hyper- and hypocoagulable dogs. The results suggest TF-TEG is valuable in the assessment of hemostatic function in dogs diagnosed with DIC.

Monitoring of antiplatelet therapy in patients at cardiovascular risk is difficult because existing platelet function tests are too sophisticated for clinical routine. The whole blood TEG^® Platelet Mapping™ assay measures clot strength as maximal amplitude (MA) and enables for quantification of platelet function, including the contribution of the adenosine diphosphate (ADP) and thromboxane A2 (TxA2) receptors to clot formation. In 43 healthy blood donors, the analytical (CV _a ) and inter-individual variability (CV _g ) of the TEG^® Platelet Mapping™ assay were determined together with platelet receptor inhibition in response to arachidonic acid (AA) and ADP. The CV _a of the assay for maximal platelet contribution to clot strength (MA _Thrombin ) was 3.5%, for the fibrin contribution to clot strength (MA _Fibrin ) 5.2%, for MA _AA 4.5% and for MA _ADP it was 6.6%. The MA _Thrombin CV _g was 2.8%, MA _Fibrin 4.7%, MA _AA 6.6% and for MA _ADP it was 26.2%. Females had a higher MA _Thrombin compared to males (62.8 vs. 58.4 mm, p = 0.005). The platelet TxA2 receptor inhibition was 1.2% (range 0–10%) and lower than for the ADP receptor (18.6% (0–58%); p < 0.0001). The high variability in ADP receptor inhibition may explain both the differences in response to ADP receptor inhibitor therapy and why major bleeding sometimes develops during surgery in patients not treated with ADP receptor inhibitors. An analytical variation of ~5 % for the TEG^® enables, however, for routine monitoring of the variability in ADP receptor inhibition and of antiplatelet therapy.