Kaolin-activated Thromboelastography Research Articles

Effect of 10-Day Treatment with 50 mg Prednisolone Once-Daily on Haemostasis in Healthy Men-A Randomised Placebo-Controlled Trial.

Synthetic corticosteroids are widely used due to their anti-inflammatory and immunosuppressant effects. Their use has been associated with venous thromboembolism, but it is unknown whether thromboembolism has a causal relationship with corticosteroid treatment. In a randomised, double-blind, placebo-controlled trial in normal to overweight healthy men, the effect of the corticosteroid prednisolone on haemostasis using either 50 mg prednisolone or matching placebo once daily for ten days was investigated. The primary outcome was a change from baseline in the viscoelastic measurement maximal amplitude of clot in kaolin-activated thromboelastography (TEG). Changes from baseline in other TEG measurements, D-dimer, von Willebrand factor (VWF) antigen, and ristocetin cofactor activity (RCo), antithrombin, protein C, prothrombin, fibrinogen, INR, APTT, and platelet count were secondary outcomes. Thirty-four men participated in this study. Compared to placebo, prednisolone treatment did not affect maximal amplitude of clot (difference -0.77 (95% confidence interval (CI) -2.48, 0.94) mm, p = 0.37, missing: n = 2), but it altered VWF antigen (28%, p = 0.0004), VWF:RCo (19%, p = 0.0006), prothrombin (5%, p = 0.05), protein C (31%, p < 0.0001), antithrombin (5%, p = 0.013), and fibrinogen (-15%, p = 0.004). Thus, prednisolone treatment did not alter TEG-assessed maximal amplitude of clot, despite that it affected prothrombotic markers (increased prothrombin, VWF antigen, VWF:RCo, prothrombin, and decreased fibrinogen) and increased antithrombotic markers (protein C and antithrombin).

Safety profile of repeated infusion of platelet-like nanoparticles in healthy dogs.

To assess the safety and efficacy of the platelet-like nanoparticle (PLN), and to assess its safety in repeated administration. 6 purpose-bred dogs. The PLN was administered IV at 3 different doses using a randomized crossover design. Each dog received a full dose of 8 X 1010 particles/10 kg, half dose, and 10 times the dose, with a 14-day washout period between doses. Biochemical, prothrombin time, partial thromboplastin time, and fibrinogen analyses were performed at baseline and 96 hours postinfusion. A CBC, kaolin-activated thromboelastography, platelet function assay closure time, and buccal mucosal bleeding time were performed at baseline and 1, 6, 24, 48, 72, and 96 hours postinfusion. No significant changes were observed over time in the thromboelastography parameters, closure time, and buccal mucosal bleeding time. After the administration of the half dose, hematocrit levels decreased significantly at 1, 6, 24, 48, and 96 hours, with all values within the reference range. The platelet count was decreased significantly at hours 1, 6, 24, 48, and 72 after administration of the half dose, with values less than the reference range at all hours but hour 72. No significant changes in serum biochemistry, coagulation panel, and fibrinogen were observed for all doses. No adverse events were noted during the first infusion. Three dogs experienced transient sedation and nausea after repeat infusion. The PLN resulted in a dilution of hematocrit and platelets, and did not significantly alter hemostasis negatively. The safety of repeated doses should be investigated further in dogs.

In vitro evaluation of canine whole blood with the addition of Crotalus atrox (Western Diamondback Rattlesnake) venom and antivenom using thromboelastography.

To compare the efficacy of 2 equine-origin antivenom products on correction of coagulation abnormalities noted on thromboelastography (TEG) caused by Crotalus atrox venom in vitro. Prospective in vitro controlled study. Veterinary teaching hospital. Six healthy dogs. Blood from each dog was used for 4 separate kaolin-activated TEG analyses: A negative control (blood-saline) and positive control (blood-Crotalus atrox venom) were used to assess the dog's normal coagulation and the effect of venom on TEG parameters. Thromboelastographic analyses were then run with blood, venom, and either Argentinian or North American antivenom. All TEG analyses from each dog were compared for efficacy. The mean R values between the North American antivenom and negative controls were not significantly different (P=0.681), but were significantly different (P=0.024) between the Argentinian antivenom and negative controls. The mean fibrinolysis values measured 30minutes after maximum amplitude achieved between the North American antivenom and negative controls were not significantly different (P=0.198), but were significantly different (P<0.001) between the Argentinian antivenom and negative controls. The mean K values between the Argentinian antivenom and negative controls were not significantly different (P=0.274), but were significantly different (P=0.043) between the North American antivenom and negative controls. The North American antivenom normalized time to clot formation and fibrinolysis, while the Argentinian antivenom normalized rate of clot formation. Further studies in naturally envenomated patients are necessary to determine if these in vitro results would translate into different clinical outcomes.

Pre-operative Hemostatic Status in Dogs Undergoing Splenectomy for Splenic Masses

Portal system thrombosis is a rare but potentially fatal complication of splenectomy in dogs. The mechanism behind development of post-operative portal system thrombosis is unclear but may include alterations of portal blood flow following surgery, acquired hypercoagulability and endothelial dysfunction. The aim of the study was to evaluate hemostatic biomarkers in hemodynamically stable (heart rate <130 beats/min, blood lactate < 2.5 mMol/L) and non-anemic (hematocrit >35%) dogs prior to splenectomy for splenic masses. Our hypothesis was that this population of stable dogs would have pre-existing laboratory evidence of hypercoagulability unrelated to shock, bleeding, anemia, or other pre-operative comorbidities. Pre-operatively, abdominal ultrasonography was performed and blood was collected for platelet enumeration, prothrombin time (PT), activated partial thromboplastin time (aPTT), kaolin-activated thromboelastography (TEG), fibrinogen, von Willebrand factor activity (vWF:Ag), antithrombin and thrombin-antithrombin complex (TAT). Histopathological diagnosis and 30-day survival were recorded. None of the 15 enrolled dogs had pre-operative sonographic evidence of portal system thrombosis. Three of fifteen dogs were thrombocytopenic, three had thrombocytosis, three were hyperfibrinogenemic, one had low vWF:Ag, three had mild prolongations of PT and none had abnormal aPTT. Based on the TEG G value, 13/15 dogs were hypercoagulable (mean ± SD 13.5 ± 5.4 kd/s). Antithrombin deficiency was identified in 9/15 dogs (mean ± SD 68.7 ± 22.7%) with 5/9 having concurrently elevated TAT suggesting active thrombin generation. No dogs developed portal system thrombosis and all achieved 30-day survival. Pre-operative hypercoagulability was recognized commonly but its association with post-operative thrombosis remains undetermined.

Correlation Between D-Dimer Concentrations and Thromboelastography in Dogs With Critical Illness: A Retrospective, Cross-Sectional Study.

A hospital-based, retrospective, cross-sectional study was performed to assess the correlation of kaolin-activated thromboelastography (TEG) with D-dimer concentrations in 59 dogs with critical illness. Dogs were included if they had one or more serious disease detected upon performing TEG and D-dimer concentration determination based on the same blood sample. According to the coagulation index (CI), the 59 dogs were divided into two groups: a hypercoagulable state, with CI > 4 (44 dogs) and a normocoagulable state, with CI < 4 (15 dogs). Moreover, the 44 dogs with CI > 4 were divided into three sub-groups according to the disease etiology, i.e., inflammatory/tumor (I/T: 25 dogs), hemodynamic compromise (H: 11 dogs), and both conditions (I/TH: 8 dogs). The median values (interquartile ranges) of the CI and D-dimer concentration were 5.46 (4.55–6.33) and 410.25 (74.63–2206.12) in the 44 dogs with CI > 4 and 3.29 (2.92–3.75) and 1164.7 (50–2250.05) in the 15 dogs with CI < 4, respectively. The D-dimer concentration was significantly increased over the reference value in the 44 dogs with a CI > 4, particularly in dogs in the I/T group. It was also significantly increased in the 15 dogs with a CI < 4. D-dimer concentrations did not correlate with any of the TEG parameters in any of the dogs. Given this lack of correlation, the D-dimer concentration may be limited as an indicator of a possible hypercoagulable state in dogs with critical illness.

WHOLE BLOOD THROMBOELASTOGRAPHY IN HEALTHY ADULT CAMELIDS (VICUGNA PACOS AND CAMELUS DROMEDARIUS).

Thromboelastography (TEG) provides a global assessment of hemostasis and fibrinolysis and has broad applications to identify and monitor coagulation dysfunction in veterinary patients. Although alpacas are susceptible to a wide variety of coagulopathies, the assessment of TEG has not been reported in clinically healthy alpacas to date. The purpose of this study was to evaluate the analytical performance of recombinant human tissue factor (rhTF)- and kaolin-activated TEG and to establish reference intervals for TEG parameters (reaction [R] and clotting [K] times, angle [α], maximum amplitude [MA], and shear elastic modulus [G]) in healthy, adult alpacas. Kaolin and rhTF-activated TEG were performed using citrated whole blood samples from 20 clinically healthy, nonpregnant, adult Huacaya alpacas each after 30 min of sample storage at room temperature. Six individuals of a related species, dromedary camels, were also sampled for comparative purposes. All data were presented descriptively, assessed for normality, and compared using either independent-sample t tests or Mann-Whitney U tests, with P ≤ 0.05 considered significant. Reference intervals were calculated using a robust method and Box-Cox-transformed data. Mean TEG values (reference intervals) were determined for rhTF-activated TEG as follows: R 6.99 min (3.41-12.71), K 3.43 min (1.61-6.42), α 48.51° (27.21-67.38), MA 52.05 mm (21.53-65.92), and G 5.71 kdyn/cm2 (1.87-9.60), while mean values (reference intervals) for kaolin-activated TEG included R 7.72 min (4.48-11.43), K 4.24 min (2.03-9.20), α 45.06° (23.66-64.20), MA 52.18 mm (33.49-66.63), and G 5.78 kdyn/cm2 (NR-9.66). None of the measured TEG values differed significantly between activators, suggesting that activator choice may have a limited effect on TEG parameters in healthy alpacas. TEG results in alpacas were comparable to those of dromedary camels. These results will thus provide a useful starting point in the evaluation of hemostasis in adult camelids.

Influence of long-stay jugular catheters on hemostatic variables in healthy dogs.

To compare hemostatic variables performed on blood samples obtained from indwelling jugular catheters or direct venipuncture over a 72-hour period. Prospective experimental study. University research laboratory. Five healthy neutered male purpose-bred Beagle dogs. Each dog was sedated to facilitate placement of a long-stay 20-Ga polyurethane IV catheter into the jugular vein. Blood samples were obtained from the preplaced catheters at 4 time points corresponding to 0, 24, 48, and 72hours relative to placement. Blood samples were also obtained by direct venipuncture of a peripheral vein using a 21-Ga butterfly catheter and evacuated blood tubes at the same time points. Platelet count, platelet closure time, prothrombin time, activated partial thromboplastin time, fibrinogen, and kaolin-activated thromboelastography were performed on these paired samples at each time point. The patency of the indwelling catheters was maintained by flushing every 6hours with heparinized saline. No significant differences were identified in any of the hemostatic variables obtained by either blood collection technique at any time point during the study (P>0.05). There was also no significant day-to-day variation in any catheter-derived hemostatic variable obtained from individual dogs identified over the course of the study. These data suggest that accurate hemostatic variables may be obtained using blood collected from indwelling jugular catheters, maintained with heparinized saline for at least 72hours, in healthy dogs.

Thermally driven formation of polyphenolic carbonized nanogels with high anticoagulant activity from polysaccharides.

We have demonstrated that alginate with negligible anticoagulant activity can be converted into carbonized nanogels with potent anticoagulant activity through a solid-state heating process. The conversion of alginate into graphene-like nanosheet (GNS)-embedded polyphenolic-alginate nanogels (GNS/Alg-NGs) has been carried out through condensation and carbonization processes. The GNS/Alg-NGs exhibit much stronger anticoagulant activity (>520-fold) compared to untreated alginate, mainly because their polyphenolic structures have a high binding affinity [dissociation constant (Kd) = 2.1 × 10-10 M] toward thrombin. In addition, the thrombin clotting time delay caused by the GNS/Alg-NGs is 10-fold longer than that of natural polyphenolic compounds, such as quercetin, catechin, naringenin, caffeic acid, and ferulic acid. The thrombin- or kaolin-activated thromboelastography of whole-blood coagulation reveals that the GNS/Alg-NGs display a much stronger anticoagulant ability than that of untreated alginate and naturally sulfated polysaccharides (fucoidan). The GNS/Alg-NGs exhibit superior biocompatibility and anticoagulant activity, as observed with an in vivo rat model, revealing their potential as a blood thinner for the treatment of thrombotic disorders.

Thromboelastography in cats with cholestatic liver disease.

While thromboelastography (TEG) has helped define a complex state of hemostasis in dogs and humans with hepatobiliary disease, it has not been explored in cats with cholestatic liver disease (CLD). The objective of this study was to describe TEG parameters in cats with CLD and to compare these parameters with conventional plasma-based coagulation tests, white blood cell (WBC) count and biochemical indicators of liver disease grade and severity. Eighteen cats with CLD, defined by a serum bilirubin ⩾3 mg/dl and a greater than two-fold increase in serum alanine aminotransferase (ALT) and/or alkaline phosphatase (ALP) activity, were prospectively enrolled. All cats received vitamin K1 subcutaneously for 24-36 h prior to acquisition of blood for kaolin-activated TEG analysis, prothrombin time (PT) and activated partial thromboplastin time (aPTT). Patient total solids, packed cell volume, platelet count, WBC count, and serum liver enzymes and bilirubin were extracted from the medical record and correlated with coagulation test results. TEG global clot strength (TEG G) values defined 9/18 (50%), 5/18 (28%) and 4/18 (22%) cats as hypercoagulable, normocoagulable or hypocoagulable, respectively. TEG G was significantly negatively correlated with PT, aPTT and serum ALP activity and positively correlated with total solids. Five cats (5/18, 28%) were hyperfibrinolytic with clot lysis at 60 mins (LY 60) >15.3%. LY 60 was significantly positively correlated with PT. By TEG analysis, cholestatic cats replete with vitamin K1 display a variety of coagulation profiles. Indications of synthetic failure (prolonged PT and aPTT) were associated with hypocoagulable and hyperfibrinolytic TEG parameters. High disease activity (serum ALP) was associated with a hypocoagulable state.

The influence of packed cell volume versus plasma proteins on thromboelastographic variables in canine blood.

Determine the correlation between kaolin-activated thromboelastography (TEG) variables (R, K, angle, and maximum amplitude [MA]) and PCV, fibrinogen concentration (FC), and total fibrinogen (TF) in an ex vivo model. Two healthy adult mixed-breed dogs. Citrated whole blood was obtained and separated into packed red cells, platelet rich plasma, and platelet poor plasma (PPP). An aliquot of PPP was heated to denature heat labile proteins (fibrinogen, factor V, factor VIII). Blood components were recombined for analyses of 6 physiological scenarios: anemia with low fibrinogen; anemia with moderate fibrinogen; anemia with normal fibrinogen; anemia with normal saline; normal PCV and normal fibrinogen; and normal PCV and low fibrinogen. A Kruskal-Wallis test, along with linear regressions on pairwise combinations of TEG variables, was used to determine the correlation between TEG variables and PCV, FC, and TF. Maximum amplitude correlated with FC (R2 0.60, P< 0.001) and TF (R2 0.57, P< 0.001) but not PCV (R2 0.003, P= 0.7). Angle and K time were moderately correlated with FC ([angle: R2 0.53, P< 0.001]; [K: R2 0.55, P< 0.001]) and TF ([alpha angle: R2 0.52, P< 0.001]; [K: R2 0.51, P< 0.001]) but not PCV. The R time was weakly correlated with PCV (R2 0.15, P< 0.009) but not FC or TF. In an ex vivo model, plasma proteins but not PCV impacted TEG variables. This suggests that TEG changes noted with anemia are imparted by changes in available fibrinogen in a fixed microenvironment rather than artifact of anemia.

Establishment of thromboelastography reference intervals by indirect method and relevant factor analyses.

Thromboelastography (TEG) as a global coagulation test has been continuously developed for many decades in either research or clinical practice. The versatility of TEG test leads to difficulty in standardization and result interpretation. Reference intervals (RIs) of TEG may be one of the most controversial factors that influence its wide applications. RIs establishment with the traditional method is time‐consuming and laborious as well as beyond general laboratory capability. Indirect method using stored data and with statistical calculation and small cost is emerging as an alternative approach for RIs determination. Gender, age, or both affect RIs and must be taken into account before RIs estimation. The present study retrospectively collected a total of 930 TEG results as subjects and established RIs with indirect method for Kaolin‐activated TEG, including the parameters of R, K, αAngle, MA, and CI. Furthermore, gender, age, and gender‐dependent age subsets analyses were performed to determine their effects on RIs of TEG. In this study, we found that TEG parameters showed more hypercoagulability in female than male, most of the measured TEG variables were significantly associated with aging, but only in male statistical significance was found among different age stratification and 60‐year‐old could be considered as cutting point to differentiate coagulation ability in male. In addition, RIs of TEG were estimated by indirect method suitably and verified to be valid in our study. Finally, the RIs of TEG by indirect method were basically significantly different to the RIs recommended by manufacturer, but the consistent percentage is relatively high in the most of measured parameters. In conclusion, it is suggestive that the indirect method for RIs establishment is feasible, but relevant factors, such as gender and age, specifically gender‐dependent age effect, should be considered before RIs determinations.

Age- and gender-related reference ranges for thromboelastography from a healthy Indian population.

Thromboelastography (TEG) is a whole blood clotting assay largely used in major surgeries and trauma to monitor patients' in vivo hemostatic status. Standardization of kaolin-activated citrated whole blood thromboelastography is not done in the Indian population. This study primarily aims to derive reference ranges of kaolin-activated TEG for healthy volunteers in the Indian population. Secondarily, it aims to study the age- and gender-related hemostatic changes in the study population. A total of 120 healthy volunteers were enrolled (55 adult males, 32 adult females, and 33 children). The volunteers were interviewed for any bleeding history or drug intake which affects coagulation. Kaolin-activated TEG was performed on citrated whole blood, and parameters including R-time, K-time, angle, MA, LY30, and CI were analyzed. Derived reference range for total volunteers irrespective of age and sex were as follows: R-time: 3.8-10.6, K-time: 1.2-3.1, angle: 44.9-72.0, MA: 41.2-64.5, LY30: 0-9.9, and CI: -3.7 to 3.4. Statistically significant difference was observed in different age and sex groups for R-time, K-time, and angle. About 40% of the volunteers had at least one abnormal parameter according to the manufacturer's reference range which decreased to 12.5% when the derived reference ranges were considered. Gender- and age-related variances were observed in reference ranges of our population and which was also differed from the other ethnic population. Many of our healthy volunteers were categorized as coagulopathic when manufacturer's reference range was considered. So, it is important to derive the reference range of the target population before using the TEG into clinical practice.

Thromboelastography Better Reflects Hemostatic Abnormalities in Cirrhotics Compared With the International Normalized Ratio.

The goal of this study was to describe potential key differences in thromboelastography (TEG) variables in hospitalized cirrhotics compared with a healthy population, identify patterns of hematologic disturbance with disease progression, and assess the value of traditional tests such as international normalized ratio (INR) and platelet count to determine coagulopathy in cirrhotics. TEG, a functional assay of coagulation, has emerged as a useful tool for predicting bleeding risk in cirrhosis. Hospitalized cirrhotics who received a TEG before any blood products between January 2017 and February 2018 at a liver transplant center were included. Reaction time (r-time), coagulation time (k-time), angle-rate of clot polymerization (α) and maximum clot strength (maximum amplitude) were measured with kaolin-activated citrated blood TEG assays. A total of 106 cirrhotic patients (Child-Turcotte-Pugh A, B, C; n=25, 25, 56) were identified for comparison against data from 53 healthy controls. TEG parameters in cirrhotics were statistically different from controls. Mean INR and platelet count for all cirrhotics were largely outside the normal reference range, contrary to TEG parameters which demonstrated parameters mostly within the normal reference ranges. The r-time, k-time, and α values in the cirrhotics progressively increased and maximum amplitude values progressively decreased as the liver disease progressed. Regression analysis showed no significant correlations between INR and r-time across any Child-Turcotte-Pugh class (r=0.01, 0.18, 0.23; P=0.95, 0.39, 0.08, respectively). Although cirrhotics had TEG parameters within normal ranges, there was a propensity for decreased clot formation as liver function worsened. Importantly, the INR did not correlate with TEG parameters in cirrhotic patients, and given the precarious hemostatic balance in these patients, a TEG may be a better predictor of bleeding risk.

Trimester-specific reference intervals for kaolin-activated thromboelastography (TEG®) in healthy Chinese pregnant women

ObjectiveThere has been little published work about the reference intervals of thromboelastography (TEG®) tests in pregnancy. Our aim was to establish the trimester-specific reference intervals of TEG tests for healthy pregnant women. MethodsAfter excluding outliers, a total of 753 apparently healthy pregnant women aged from 19 to 44 years including 252 first trimester women, 340 second trimester women and 161 third trimester women were enrolled in our study. Non-fasting venous blood samples were collected. TEG tests were done on kaolin activated samples and processed on TEG 5000 Hemostasis Analyzer. Nonparametric 2.5th–97.5th percentile intervals were used to define the reference intervals. ResultsThere were significant differences for TEG tests in pregnant women compared with non-pregnant women. The reference intervals for R, K, Angle, MA, Ly30 and CI were 4.1–10.4 min, 0.9–3.1 min, 53.6–75.9°, 46.1–69.8 mm, 0–10.7% and −5.5–2.5 respectively at first trimester; 3.9–9.7 min, 0.8–2.4 min, 56.7–78.0°, 49.8–72.1 mm, 0–9.7% and −3.7–2.9 at second trimester; 3.8–9.0 min, 0.8–2.5 min, 57.6–79.3°, 49.4–75.9 mm, 0–8.8% and −3.0–2.6 at third trimester. ConclusionsWe established trimester-specific reference intervals of TEG® tests for healthy pregnant women. It's critical to accurate assessment of global haemostatic status during pregnancy and in pregnancy complications.

A prospective evaluation of oral Yunnan Baiyao therapy on thromboelastographic parameters in apparently healthy cats

To determine the effect of Yunnan Baiyao (YB) on hemostatic parameters measured by thromboelastography (TEG) in apparently healthy cats administered 1 capsule of YB orally twice daily for 1 week. Prospective study of client-owned cats at a small animal specialty hospital. One private referral center. Twenty client-owned adult cats were prospectively enrolled. All cats underwent echocardiographic examination by the same board-certified cardiologist to rule out occult cardiomyopathy. Blood samples were collected for analysis of baseline CBC, fibrinogen, and kaolin-activated TEG values. Cats were administered 1 capsule (250 mg/capsule) of YB twice daily orally for 1 week and the physical examination, CBC, fibrinogen, and TEG were re-evaluated. Any side effects attributed to YB were noted at this time. Three cats were excluded as 2 cats were identified with underlying cardiomyopathy and another cat had a cystic mass in the cranial mediastinum identified via echocardiography. Seventeen cats were treated with YB; however, 1 cat could not complete the study due to severe vomiting associated with YB administration. The remaining 16 cats completed the study, although 2 additional cats experienced transient vomiting. Yunnan Baiyao administration was associated with a significant decrease in HCT and red blood cell count, although no cat became anemic. None of the TEG parameters significantly changed compared to baseline after 1 week of YB therapy. The results of this study suggest YB at a dose of 1 capsule orally twice daily in cats fails to produce any significant change in hemostatic parameters as measured by TEG, although it did significantly reduce HCT and red blood cell count. Yunnan Baiyao was tolerated for most of the cats, although 3 of 17 (17.6%) cats experienced vomiting. Clinicians should be aware of these effects before considering the use of YB in cats.

A prospective evaluation of rivaroxaban on haemostatic parameters in apparently healthy dogs.

The purpose of this study was to determine the effect of rivaroxaban (RIV) on haemostatic parameters assessed by prothrombin time (PT), activated partial thromboplastin time (aPTT) and kaolin‐activated thromboelastography (TEG) in apparently healthy dogs administered 1 mg kg−1 orally once daily for 1 week. Eleven dogs had a baseline complete blood count (CBC), fibrinogen, platelet count, serum chemistry profile, PT, aPTT, and TEG performed. Each dog was then administered approximately 1.0 mg kg−1 of RIV orally once daily for 1 week and the CBC, fibrinogen, platelet count, serum chemistry profile, PT, aPTT, and TEG was re‐evaluated. Any side effects attributed to RIV were noted at this time. One dog was excluded due to identification of a macrocytic thrombocytopenia on pre‐treatment blood work. The remaining 10 enrolled dogs completed the study. Dogs received a median dose of 1.02 mg kg−1 (range 0.94–1.17 mg kg−1) of RIV once daily and was associated with a significant increase in pulse, packed cell volume, total solids, platelet count, fibrinogen and a significant decrease in mean corpuscular haemoglobin and mean corpuscular haemoglobin concentration. There was no significant change in PT, aPTT or any TEG parameters. The RIV appeared well tolerated with one dog having one episode of vomiting on day 4 but otherwise no other side effects were identified clinically or on recheck blood work. The results of this study suggests that RIV at a dose of 1 mg kg−1 orally once daily is safe and well tolerated but does not cause a significant prolongation of PT, aPTT or TEG parameters.

Evaluation of kaolin-activated thromboelastography and sample stability in healthy horses

Thromboelastography is an accurate alternative to routine coagulation testing for the monitoring of haemostasis. However, its use in equine medicine is limited not only by the lack of reference interval values for kaolin-activated citrated samples, but also by the limited accessibility of the test for field practitioners within the 2-hour storage time recommended by the manufacturer. To address this issue, we here evaluated kaolin-activated thromboelastography using a TEG&lt;sup&gt;®&lt;/sup&gt; 5000 Thrombelastograph&lt;sup&gt;®&lt;/sup&gt; Hemostasis System in 36 healthy horses, and sample stability was evaluated at four timepoints post collection in seven horses. Reference values were established as follows: reaction-time 5.0–16.0 min, K-time (period in which the clot strength reaches 20 mm of amplitude) 1.1–5.2 min, α-angle (speed of fibrin cross-linking) 36.5–79.0°, maximal amplitude 44.5–69.7 mm, fibrinolysis 30 minutes after maximal amplitude was reached 0.0–2.8%. During storage, the trends in the changes of values were similar for most parameters, and values remained mostly within the reference intervals. Thromboelastography is thus useful in defining thrombohaemorrhagic complications in horses but can be sensitive to preanalytical factors and storage.

Thromboelastographic evaluation of dogs bitten by rattlesnakes native to southern California.

OBJECTIVE To validate that dogs become hypocoagulable following rattlesnake envenomation and to determine whether thromboelastographic abnormalities are correlated with envenomation severity for dogs bitten by rattlesnakes native to southern California. ANIMALS 14 dogs with observed or suspected rattlesnake envenomation (envenomated dogs) and 10 healthy control dogs. PROCEDURES For each dog, a citrate-anticoagulated blood sample underwent kaolin-activated thromboelastography. For each envenomated dog, a snakebite severity score was assigned on the basis of clinical findings, and prothrombin time, activated partial thromboplastin time, and platelet count were determined when the attending clinician deemed it necessary and owner finances allowed. RESULTS For 12 of 14 envenomated dogs, the thromboelastographically determined clot strength was below the 25th percentile for the clot strength of control dogs, which was indicative of a hypocoagulable state. No envenomated dog had thromboelastographic results indicative of a hypercoagulable state. One envenomated dog had a prolonged prothrombin time, but the activated partial thromboplastin time and all thromboelastographic variables were within the respective reference ranges for that dog. Seven of 13 envenomated dogs were thrombocytopenic (platelet count, ≤ 170,000 platelets/μL). Snakebite severity score was negatively correlated with platelet count but was not correlated with any thromboelastographic variable. CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that dogs generally become hypocoagulable following rattlesnake envenomation. Thromboelastography might provide an objective measure of the coagulation status of envenomated dogs and aid in the identification of dogs that are in a hypocoagulable state and in need of antivenin treatment prior to the onset of progressive clinical signs.

THROMBOELASTOGRAPHY IN THE HEALTHY ASIAN ELEPHANT ( ELEPHAS MAXIMUS): REFERENCE INTERVALS AND EFFECTS OF STORAGE.

Hemorrhagic disease associated with elephant endotheliotropic herpesvirus infection is the most-frequent cause of mortality in captive Asian elephants ( Elephas maximus). Survival relies on intensive monitoring of hemostatic status. Thromboelastography (TEG) utilizes whole blood samples containing all the blood components of hemostasis and is therefore a sensitive indicator of the clinical status in the patient. This study was performed to assess the practicability of TEG in Asian elephants in a zoo environment. Citrated stabilized whole blood samples were obtained from 44 healthy Asian elephants. Kaolin-activated TEG was performed on whole blood at 60 min and 24 hr postsampling (to replicate shipment to an external laboratory) as well as on freeze-thawed plasma samples, 12-14 mo postsampling. Reference intervals were calculated for fresh whole blood and freeze-thawed plasma samples. In the 24-hr analysis, storage artifacts, likely due to cellular degeneration, resulted in a hypercoagulable thromboelastogram and thus reduced sensitivity for detecting coagulopathies. Therefore, delayed analysis of whole blood samples is not recommended.

Evaluation of thromboelastography in bitches with pyometra.

We investigated the effect of pyometra on kaolin-activated thromboelastography (TEG). Eighteen client-owned dogs with pyometra and 8 healthy spayed dogs were recruited. TEG parameters and packed cell volume were determined. Results from spayed females and from intact females with pyometra were compared using a Student t-test and Wilcoxon rank sum test. Bitches with pyometra were hypercoagulable compared to spayed bitches as evidenced by elevated maximum amplitude, G, and alpha angle. There were no significant group differences in R time, K time, or clot lysis at 30 or 60 min. Dogs with pyometra should be anticipated to have hypercoagulable TEG variables, and this should be addressed when planning surgical and medical therapy.