Evaluation of human recombinant tissue factor-activated thromboelastography in 49 dogs with neoplasia

BACKGROUND: Abnormal routine coagulation assay results have been reported to be common in veterinary patients with neoplasia, but the overall hemostatic functional state, including hypercoagulability, has not been described. HYPOTHESIS: The overall hemostatic functional state, including hypercoagulability, can be assessed in dogs with neoplasia by tissue factor (TF)-activated thromboelastography (TEG). ANIMALS: Thirty-six dogs with malignant neoplasia and 13 dogs with benign neoplasia presented to the Small Animal Veterinary Teaching Hospital, The University of Copenhagen, Frederiksberg, Denmark. METHODS: Prospective study evaluating the overall hemostatic functional state in dogs with neoplasia by a newly validated TF-activated TEG assay and routine coagulation parameters activated partial thromboplastin time (aPTT), prothrombin time (PT), platelet count, and D-dimer concentration. RESULTS: Hemostatic dysfunction was observed in 28/49 (57%) dogs with neoplasia. Twenty-four were dogs with malignant neoplasia, the majority of which 18/36 (50%) were hypercoagulable, whereas 6/36 (17%) were hypocoagulable. All hypocoagulable dogs had metastatic disease. The proportion of dogs with altered hemostasis was significantly different between dogs with malignant and benign neoplasia. CONCLUSIONS AND CLINICAL IMPORTANCE: TF-activated TEG detected hypercoagulable and hypocoagulable states in this population of dogs with neoplasia. The most common hemostatic abnormality in dogs with malignant neoplasia was hypercoagulability. These findings suggest that this novel hemostatic function test may be of value as a cage side method for the assessment of overall hemostatic function in dogs with cancer, including the detection of both hyper- and hypocoagulable states as well as mixed disorders.     

Hemostatic abnormalities in dogs with carcinoma: a thromboelastographic characterization of hypercoagulability

Hemostatic abnormalities were investigated in 32 dogs with carcinoma and 19 age-matched healthy dogs. Thromboelastography, hemostasis profile (i.e. prothrombin time [PT], activated partial thromboplastin time [aPTT], fibrinogen concentration), platelet count (PLT), thrombin-antithrombin complexes (TAT), and plasminogen activator inhibitor-1 (PAI-1) activity were evaluated. Dogs with carcinomas had faster thrombus generation (TEG(TG), a mathematic value obtained from the first derivate of the thromboelastographic tracing; 834.8±91.1 vs. 707.8±75.8mm/min; mean±SD), increased fibrinogen concentration (276 vs. 151mg/dL), and PLT (425 vs. 324U×10(9)/L), but had decreased PAI-1 activity (15.7 vs. 26.2IU/mL).The most common hemostatic abnormalities found in carcinoma dogs were hypercoagulability (TEG(TG)>mean+2 SD of healthy dogs) and thrombocytosis (PLT>424×10(9)U/L) in 46% of cases, and hyperfibrinogenemia (fibrinogen >384mg/dL) in 32% of cases. Disseminated intravascular coagulation was uncommon and the extent of disease was not correlated with hypercoagulability. TEG(TG) showed good correlation with fibrinogen (r=0.80) and hyperfibrinogenemia seems to be a main factor of the hypercoagulable state in carcinoma dogs. In conclusion, TEG(TG) is a valid parameter to diagnose hypercoagulability.     

Use of thromboelastography in dogs with immune-mediated hemolytic anemia: 39 cases (2000–2008)

Objective – To analyze thromboelastograms (TEGs) of naturally occurring cases of immune-mediated hemolytic anemia (IMHA) in order to identify whether a hypercoagulable state was present and whether its presence was associated with differences in survival.
Design – Retrospective study spanning January 2000 to June 2008. Medical records of dogs were evaluated. Endpoints were considered death or discharge from the hospital.
Setting – Academic teaching hospital.
Animals – Thirty-nine dogs with a diagnosis of IMHA and at least one TEG performed during hospitalization were included.
Interventions – None.
Measurements and Main Results – Four values were evaluated from the TEG: the R time (R), K time (K), alpha angle (α), and maximum amplitude. From these values, a coagulation index (CI) was calculated to classify patients as normocoagulable, hypercoagulable, or hypocoagulable. Thirty-three of 39 patients were hypercoagulable based on the CI. The 6 remaining dogs were normocoagulable. The patients with a normocoagulable CI had an increased mortality rate (100%) when compared with the hypercoagulable patients using Fisher's exact test ( P =0.02). Additionally, prolongation of partial thromboplastin time did not preclude hypercoagulable TEG values.
Conclusions – The majority of dogs with IMHA were hypercoagulable as measured by TEG. A normal CI was associated with a worse outcome in this patient population. TEG may provide additional and complementary information to prothrombin time and partial thromboplastin time relating to coagulation status in dogs with IMHA and may help predict prognosis and potentially guide clinical decisions to utilize anticoagulant drugs.     

Prolonged activated prothromboplastin time and breed specific variation in haemostatic analytes in healthy adult Bernese Mountain dogs

Coagulation tests are often performed in dogs suspected of haemostatic dysfunction and are interpreted according to validated laboratory reference intervals (RIs). Breed specific RIs for haematological and biochemical analytes have previously been identified in Bernese Mountain dogs, but it remains to be determined if breed specific RIs are necessary for haemostasis tests. Activated prothromboplastin time (aPTT), prothrombin time (PT), selected coagulation factors, D-dimers, fibrinogen, von Willebrand factor and thromboelastography (TEG) were analyzed in healthy Bernese Mountain dogs using the CLSI model. Three analytes (aPTT, TEG [MA] and TEG [G]) were different according to the CLSI model. For aPTT the new RI was markedly different (0-100s). Whereas the new intervals for TEG (MA) and TEG (G) may be due to breed related biological variation, the cause of the prolonged RI for aPTT is at present uncertain.     

Diagnosis of disseminated intravascular coagulation in dogs admitted to an intensive care unit.

OBJECTIVE: To describe and evaluate hemostatic function in critically ill dogs with clinical signs of diseases that predispose to disseminated intravascular coagulation (DIC). DESIGN: Prospective case series. ANIMALS: 59 critically ill dogs (affected dogs) with clinical signs of diseases known to predispose to DIC and 52 clinically normal dogs (control dogs). PROCEDURE: Activated partial thromboplastin time (aPTT), prothrombin time (PT), thrombin clotting time (TCT), plasma fibrinogen concentration, serum concentration of fibrin and fibrinogen-related antigens (FRA), and plasma antithrombin III (AT III) activity were determined for all dogs. Results from affected dogs were compared with those of control dogs. In some affected dogs, postmortem tissue specimens were examined for evidence of microvascular thrombosis. A diagnosis of DIC was made by fulfilling at least 3 of the following criteria: 1) abnormal aPTT, PT, or TCT value, 2) low plasma fibrinogen concentration, 3) low plasma AT III activity, 4) high serum FRA concentration, or 5) low platelet count. To evaluate the severity of hemostatic dysfunction, 3 arbitrary categories (mild, moderate, and severe) were proposed. RESULTS: A diagnostic strategy based on moderate hemostatic dysfunction identified DIC in 16 of 59 (27.1%) affected dogs. The AT III activity was < 70% in 15 of 16 dogs with DIC. Microvascular thrombosis was observed in tissue specimens from 7 of 8 affected dogs. Serum FRA and plasma fibrinogen concentrations did not contribute in establishing a diagnosis of DIC. CONCLUSIONS AND CLINICAL RELEVANCE: A diagnosis of DIC can be made when hemostatic dysfunction is moderate in dogs with clinical signs of diseases associated with DIC.     

Exercise induced hypercoagulability,increased von Willebrand factor and decreased thyroid hormone concentrations in sled dogs

Background

Sled dogs performing endurance races have been reported to have a high incidence of gastric erosions or ulcerations and an increased risk of gastro intestinal bleeding leading to death in some cases. In addition, these dogs also become hypothyroid during training and exercise. Canine hypothyroidism has been shown to correlate with decreased von Willebrand factor antigen and potentially increased bleeding tendency. Whether increased gastro intestinal bleeding risk is exacerbated due to changes in the hemostatic balance is unknown. The aim of this study was to investigate the hemostatic balance in sled dogs before and after exercise and in addition evaluate any correlation to thyroid status. Twenty sled dogs have been assessed in untrained and trained condition and immediately after exercise. The first sample was collected in the autumn following a resting period, and subsequently the dogs were exposed to increased intensity of training. After four months the peak of physical condition was reached and a 68 km long sled pulling exercise was performed. Samples were collected before and immediately after the exercise. Evaluated parameters were: plasma thromboelastographic (TEG) R, SP, α and MA, activated partial thromboplastin time (aPTT), prothrombin time (PT), fibrinogen, von Willebrand factor (vWf), D-dimer, platelet number, thyroid hormones, hematocrit and C-reactive protein (CRP).

Results

Exercise induced an overall hypercoagulable state characterized by significant decreases of TEG R and SP and an increase of α, increased concentrations of plasma vWf and decreased aPTT. In addition, a proinflammatory status was seen by a significant increase of serum CRP concentrations. Thyroid status was confirmed to be hypothyroid as training and exercise induced significant decrease of thyroxin (T4), free thyroxin (fT4) and thyroxin stimulating hormone (TSH) concentrations. Fibrinogen decreased significantly and PT increased. The training-induced changes showed correlation between T4, fT4 and aPTT and correlation between TSH and fibrinogen. Exercise-induced changes showed correlation between T4 and PT.

Conclusions

Exercise was associated with a hypercoagulable state and an increase of vWf concentration in this group of sled dogs. Decreased thyroid hormone concentrations after training and exercise were confirmed, but were associated with increased and not decreased vWf in this group of sled dogs.     

Relationship between assays of inflammation and coagulation: A novel interpretation of the canine activated clotting time

The processes of inflammation and coagulation are known to be interconnected through several mechanisms; however, the influence of inflammation on the interpretation of coagulation assays remains unknown. Blood was collected from 87 dogs admitted to a tertiary referral intensive care unit (ICU) and 15 control dogs. The association between 2 markers of inflammation [mature neutrophil count and C-reactive protein (CRP)] and 5 coagulation parameters [activated clotting time (ACT), prothrombin time (PT), activated partial thromboplastin time (aPTT), antithrombin (AT), and platelet count (plt)] were evaluated through correlation analysis. The study population was then divided into 4 groups based on severity of ACT prolongation with comparisons to all other variables assessed through an analysis of variance (ANOVA) test. A strong correlation for a biological system was demonstrated between ACT and CRP (r = 0.66; P < 0.0001). Statistically significant results were also found between aPTT and AT with the markers of inflammation, but the correlations were weaker. Within ACT groups of increasing severity, higher CRP concentrations (P < 0.0001) and lower AT activities (P < 0.0001) were identified. This study provides evidence for an association between assays of inflammation and coagulation and suggests that modification of our traditional interpretations of coagulation assays may be required. As a point-of-care test, ACT is a simple and inexpensive tool that can be used to assess an underlying inflammatory or hemostatic process.     

Haemostatic alterations in a group of canine cancer patients are associated with cancer type and disease progression

Background

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.

Methods

The study population consisted of 71 dogs with malignant neoplasia presented to the University Hospital for Companion Animals, Faculty of Life Sciences, University of Copenhagen, Denmark. The study was designed as a prospective observational study evaluating the haemostatic function in canine cancer patients stratified according to type of cancer disease and disease progression. The coagulation response was evaluated by thromboelastrography (TEG), platelet count, activated partial thromboplastin time (aPTT), prothombin time (PT), fibrinogen and antithrombin (AT); and fibrinolysis by d-dimer and plasminogen.

Results

Hypercoagulability was the most common haemostatic dysfunction found. Non mammary carcinomas had increased clot strength (TEG G), aPTT and fibrinogen compared to the other groups. When stratifying the patients according to disease progression dogs with distant metastatic disease exhibited significantly increased fibrinogen, and d-dimer compared to dogs with local invasive and local non-invasive cancers.

Conclusion

Hypercoagulability was confirmed as the most common haemostatic abnormality in canine cancer patients and haemostatic dysfunction in canine cancer patients was found related to the cancer type and progression of disease. Increase in TEG G, aPTT and fibrinogen were observed in non-mammary carcinomas and were speculated to overall represent a proinflammatory response associated with the disease. Dogs with distant metastatic disease exhibited increased fibrinogen and d-dimer. Future studies are needed to elucidate the clinical importance of these results.     

The influence of inflammation and hematocrit on clot strength in canine thromboelastographic hypercoagulability

Objective

To investigate parameters causing canine thromboelastographic hypercoagulability and to investigate whether thromboelastography (TEG) with Cytochalasin D (Cyt D) added is related to parameters of platelet activity.

Design

Prospective observational study on hemostatic and inflammatory parameters. Data were collected between November 2012 and July 2013.

Setting

University teaching hospital.

Animals

Twenty‐eight dogs suffering from diseases predisposing to thrombosis and 19 clinically healthy dogs. Diseased dogs were enrolled if they fulfilled inclusion criteria regarding age, size, informed client consent, and obtained a diagnosis of a disease that has been associated with thrombosis or hypercoagulability.

Interventions

None.

Measurements and Main Results

Parameters of coagulation and anticoagulation, fibrinolysis, and antifibrinolysis, platelet activity, inflammation, platelet count, and hematocrit were measured using CBC, TEG, platelet aggregation on multiplate, platelet activity on flow cytometry, and hemostatic and inflammatory markers on plasma and serum analyses. ANOVA and multilinear regression analyses indicated that especially hematocrit and the inflammatory parameters C‐reactive protein and interleukin‐8 showed best association with overall clot strength in diseased dogs with hypercoagulable TEG tracings. Ratios presumed to reflect platelet contribution to the TEG tracing obtained in TEG analyses with Cyt D were related especially with hematocrit and P‐selectin expression of platelets measured after γ‐Thrombin activation on flow cytometry.

Conclusion

Overall clot strength in TEG analyses of the hypercoagulable dogs included in the present study appears to be primarily associated with inflammation as well as hematocrit. Furthermore, the ratio between standard TEG analyses and TEG analyses with Cyt D may reflect some degree of platelet activity.     

Effect of experimental endotoxemia on thrombelastography parameters, secondary and tertiary hemostasis in dogs

Background: Thrombelastography (TEG) and indicators of secondary and tertiary hemostasis might be altered in dogs with endotoxemia. Hypothesis: Endotoxemia influences measures of coagulation in dogs. Animals: Ten healthy cross‐bred dogs. Material and Methods: Prospective laboratory study between controls (n = 5) receiving 0.9% saline IV and the study group (n = 5) treated with low‐dose lipopolysaccharide (0.02 mg/kg IV). Physical examination and sampling for measurement of leukocytes, platelets, and coagulation variables were performed at time points 0, 1, 4, and 24 hours. Coagulation variables included kaolin‐activated TEG, 1‐stage prothrombin time (OSPT), activated partial thromboplastin time (aPTT), fibrinogen, factor VIII, antithrombin, protein C, protein S, activated protein C (APC)‐ratio calculated from aPTT with and without presence of APC), and D‐Dimers. Results: Endotoxemia‐induced clinical signs included lethargy (n = 5/5), diarrhea (n = 4/5), emesis (n = 4/5), and abdominal pain (2/5). After 1 hour there was severe leukopenia (2.5 ± 0.7 × 10⁹/L; mean ± SD, P < .0001) and a 2.2‐fold increase in D‐Dimers (0.81 ± 0.64 mg/L, P < .0001). After 4 hours there was hyperthermia (40.3 ± 0.4°C, P < .0001) and increases in OSPT (10.5 ± 2.7 seconds, P < .0001), aPTT (16.7±5.2 seconds, P= 0.002). A significant decrease in fibrinogen (1.5±1.0 g/L, P= 0.001), protein C (31 ± 33%, P <.0001), protein S (63 ± 47%, P < .0001), TEG α (58 ± 19, P= .007), and TEG maximal amplitude (50 ± 19 mm, P= .003) was seen compared with the controls. APC‐ratio rose significantly (2.5 ± 0.2, P < .0001) without exceeding the reference interval (n = 4/5). Conclusion and Clinical Importance: D‐Dimers are the earliest indicator for endotoxemia‐associated coagulation abnormalities followed by decreased protein C concentration. APC‐ratio and TEG were not good screening variables.     

Effect of citrate concentration on coagulation test results in dogs

OBJECTIVE: To determine the effect of citrate concentration (3.2 vs 3.8%) on coagulation tests in dogs. DESIGN: Original study. ANIMALS: 30 clinically healthy dogs and 12 dogs with hereditary hemostatic disorders. PROCEDURE: Blood was collected from all dogs directly into collection tubes containing 3.2 or 3.8% buffered citrate. Prothrombin time (PT), activated partial thromboplastin time (aPTT), and fibrinogen concentration were measured by use of 3 clot-detection assay systems (2 mechanical and 1 photo-optic). Factor VIII and factor IX coagulant activities (FVIII:C and FIX:C, respectively) were determined by use of a manual tilt-tube method and a mechanical clot-detection device. RESULTS: Significant differences were not detected in median PT, fibrinogen concentration, FVIII:C, or FIX:C between 3.2 and 3.8% citrate for any assay system. A significant prolongation in aPTT for 3.2% citrate, compared with 3.8% citrate, was found in 1 mechanical system. CONCLUSIONS AND CLINICAL RELEVANCE: Citrate concentration does not significantly affect results of most coagulation assays, regardless of assay system. The aPTT was mildly influenced by the citrate concentration, although this was animal-, instrument-, and reagent-dependent. The choice of 3.2 or 3.8% citrate as an anticoagulant for coagulation tests has minimal influence on assay results in healthy dogs or dogs with hereditary hemostatic disorders.     

Examination of hemostatic parameters to detect hypercoagulability in dogs with severe protein‐losing nephropathy

Objective – To identify hemostatic abnormalities in dogs with protein‐losing nephropathies (PLN) that represent risk factors for pathologic thrombosis. Design – Cross‐sectional observational study of client‐owned dogs with PLN, nonprotein losing renal failure (RF), and systemic illness (SI) exclusive of primary renal disease. Setting – Urban University Referral Center. Animals – A total of 29 dogs (n=11 PLN, n=7 RF, n=11 SI) were enrolled between January 2001 and July 2002. Samples were also collected from 20 clinically normal dogs to serve as hemostasis assay controls. Interventions – None. Hemostasis Testing – Citrate anticoagulated blood was collected for point‐of‐care testing with a viscoelastic monitor (thromboelastograph [TEG]) and citrate plasma was prepared for coagulation screening tests and specific assay of the following hemostatic proteins: antiplasmin, antithrombin, D‐dimer, Factor VIII, fibrinogen, plasminogen, protein C, and von Willebrand factor. Results – Dogs with PLN and RF demonstrated TEG abnormalities consistent with hypercoagulability (eg, short clotting time, high clot amplitude) and both groups had significantly lower antithrombin than the SI group. The PLN dogs had significantly higher protein C than either the RF or SI group. Hyperfibrinogenemia was a consistent finding among all 3 disease groups, and the coagulation index a measure of hypercoagulability derived from TEG parameters, directly correlated with fibrinogen values of all study dogs. Conclusions – Hemostatic abnormalities consistent with systemic hypercoagulability are common in dogs with RF and PLN, however, no prothrombotic factors unique to PLN were identified in our study. The thrombotic tendency of PLN may therefore involve parameters we did not directly assess such as platelet reactivity, fibrinolysis, perturbations in blood flow, and/or endothelial dysfunction. High protein C is a novel finding in PLN dogs of unknown clinical relevance.     

Thromboelastography in healthy horses and horses with inflammatory gastrointestinal disorders and suspected coagulopathies

Objectives – To evaluate the use of citrated recalcified (nonactivated) thromboelastography (TEG) in healthy horses and horses with colitis and suspected coagulopathies. Design – Prospective, observational study conducted between October 2007 and June 2009. Setting – Veterinary Teaching Hospital. Animals – Forty‐five healthy adult horses and 12 sick adult horses with colitis and prolonged prothrombin time (PT) or activated partial thromboplastin time (aPTT). Interventions – None. Measurements and Main Results – Whole blood was collected on admission. Coagulation profile (PT, aPTT, platelet count, and fibrinogen concentration) and citrated recalcified whole blood TEG analysis (R‐time [R], K‐time [K], angle [α], maximum amplitude [MA], G value [G], lysis at 60 min [LY60]) were evaluated. Mean values (SD) for TEG parameters in healthy horses were: R=10.4 (3.1) minutes; K=3.5 (1.2) minutes; α=46.3 (11.0)°; MA=55.6 (5.1) mm; G=6,429 (1,341) dyn/cm², and LY60=5.1 (2.4)%. Mean coefficients of variation for intra‐assay/interindividual variability in healthy horses were: R=4.7%/30.7%, K=4.8%/35.3%, α=4.4%/23.8%, MA=1.4%/9.3%, G=3.4%/20.8%, and LY60=13.1%/47.7%, respectively. Horses with colitis and prolonged PT and/or aPTT had longer mean values for R (P<0.001) and K (P<0.001), narrower mean α (P<0.001), decreased mean MA (P=0.001), and smaller mean G (P=0.02); changes consistent with hypocoagulability. Conclusions – Citrated recalcified (nonactivated) TEG demonstrated changes consistent with hypocoagulability in horses with colitis that had preidentified coagulation abnormalities. This technique has high interindividual variability and low intra‐assay variability. TEG may be useful for detecting hypocoagulable states in horses with colitis and suspected coagulopathies.     

The effect of unfractionated heparin on thrombelastographic analysis in healthy dogs

Objective – To determine the effect of single and multiple doses of SQ heparin (200 U/kg) on the thrombelastogram of healthy dogs. Design – Prospective study. Setting – University research facility. Animals – Six random‐source female dogs. Interventions – Baseline parameters, including a CBC with platelet count, prothrombin time, activated partial thromboplastin time (aPTT), and antithrombin were performed. Thrombelastography (TEG) and aPTT were performed hourly for 12 hours after unfractionated heparin dosing (200 U/kg, SQ). Anti‐Xa activity was assayed at 0, 3, 6, and 8 hours. Heparin was then administered every 8 hours for 3 days. The sampling protocol on Day 4 was identical to Day 1. Measurements and Main Results – On Day 1, percentage change from baseline for TEG parameter R, as well as absolute values of K, angle, and maximum amplitude (MA) were evaluated. Statistically significant (P<0.01) prolongation of the R time and a decrease in angle and MA was seen in all dogs by hour 3. R and MA were unmeasurable for most dogs between 3 and 5 hours. All TEG tracings returned to baseline by 12 hours. Day 4 TEG tracings mimicked those on Day 1. Only 1 dog achieved aPTT values outside the reference interval on both days. Anti‐Xa activity levels increased on Day 4 but not on Day 1. Based on post hoc in vitro analysis, prolongation of R time occurred at plasma heparin levels as low as 0.075 U/mL, well below the lower limit of detection of the anti‐Xa activity level assay. Conclusions – Administration of SQ heparin results in progressive changes in the TEG tracing, with maximal change occurring 3–5 hours after dosing. The extensive prolongation of the R time also indicates that TEG may be too sensitive and limits its utility as a monitoring tool for unfractionated heparin therapy.     

Thrombelastography in horses with acute gastrointestinal disease

Background: Coagulopathies in horses with gastrointestinal disease are frequently identified and associated with morbidity and fatality. Objective: Determine if thrombelastography (TEG) identifies abnormalities associated with lesion type, presence of systemic inflammatory response syndrome (SIRS), morbidity, and fatality more consistently than traditional coagulation testing. Animals: One‐hundred and one horses examined for gastrointestinal disease and 20 healthy horses. Methods: TEG, tissue factor (TF)‐TEG, and traditional coagulation panels parameters and percentages of horses with coagulopathies were compared for lesion type, presence of SIRS, complications, and survival. Results: Changes in individual parameters and increased incidence of coagulopathies were associated with fatality (R, P= .007; k‐value [K], P= .004; clot lysis [CL]30, P= .037; CL60, P= .050; angle [Ang], P= .0003; maximum amplitude [MA], P= .006; lysis [Ly]30, P= .042; Ly60, P= .027; CI, P= .0004; ≥ 2 TEG coagulopathies, P= .013; ≥ 3 TEG coagulopathies, P= .038; TF‐R, P= .037; TF‐K, P= .004; TF‐CL30, P < .0001; TF‐CL60, P < .0001; TF‐Ang, P= .005; TF‐Ly30, P= .0002; TF‐Ly60, P < .0001; TF‐CI, P= .043; ≥ 1 TF‐TEG coagulopathies, P= .003; ≥ 2 TF‐TEG coagulopathies, P= .0004; prothrombin tme [PT], P < .0001; activated partial throboplastin time [aPTT], P= .021), inflammatory lesions (MA, P= .013; TF‐CL30, P= .033; TF‐CL60, P= .010; TF‐Ly60, P= .011; ≥ 1 TF‐TEG coagulopathy, P= .036; ≥ 2 TF‐TEG coagulopathy, P= .0007; PT, P= .0005; fibrinogen, P= .019), SIRS (MA, P= .004; TF‐CL30, P= .019; TF‐CL60, P= .013; TF‐Ly30, P= .020; TF‐Ly60, P= .010; PT, P < .0001; aPTT, P= .032; disseminated intravascular coagulation, P= .005), and complications (ileus: aPTT, P= .020; diarrhea: TF‐CL30, P= .040; TF‐Ly30, P= .041; thrombophlebitis: ≥ 1 TF‐TEG coagulopathy, P= .018; laminitis: MA, P= .004; CL60, P= .045; CI, P= .036; TF‐MA, P= .019; TF‐TEG CI, P= .019). Abnormalities in TEG and TF‐TEG parameters were indicative of hypocoagulation and hypofibrinolysis. Conclusions and Clinical Importance: TEG identifies changes in coagulation and fibrinolysis associated with lesion type, SIRS, morbidity, and fatality in horses with gastrointestinal disease.     

Study on biological variation of haemostatic parameters in clinically healthy dogs

Thromboelastography (TEG) may be a valuable supplement to the coagulation assays activated partial thromboplastin time (aPTT), prothrombin time (PT), thrombin time (TT), fibrinogen, antithrombin (AT) and D-Dimer currently used in most clinical pathology laboratories. Allowable imprecision and bias reference limits for analytical tests can be calculated based on measurements of biological variation. No studies to date have examined the effect of biological variation on these haemostasis parameters in the same group of dogs. Plasma samples were collected after a set protocol once weekly for five consecutive weeks from eight healthy dogs (four males and four females) and stored at -80 degrees C until analysis. Randomized duplicate coagulation tests and TEG analyses were performed on all plasma samples within one run. The data were analyzed for outliers and subsequently subjected to nested analysis of variance to obtain the coefficient of analytical, intra-individual and inter-individual variation. From these objective analytical performance standards for imprecision, critical difference, total error and the index of individuality were calculated to assess the utility of conventional population-based reference ranges. All the clotting times (aPTT, PT and TT), fibrinogen, AT and D-Dimer showed a degree of individuality, which may make the use of population-based reference ranges alone an insensitive interpretation criterion, whereas a population-based reference interval seems to be sensitive for interpreting all TEG parameters. Analytical performance standards for imprecision were only met for one of the coagulation assays, whereas all TEG parameters except the alpha angle, alpha achieved this analytical goal.     

Coagulation profiles of healthy Andalusian donkeys are different than those of healthy horses

Background: Coagulation disorders are frequently diagnosed, especially in hospitalized equidae, and result in increased morbidity and mortality. However, hemostatic reference intervals have not been established for donkeys yet. Objectives: To determine whether the most common coagulation parameters used in equine practice are different between healthy donkeys and horses. Animals: Thirty‐eight healthy donkeys and 29 healthy horses. Methods: Blood samples were collected to assess both coagulation and fibrinolytic systems by determination of platelet count, fibrinogen concentration, clotting times (prothrombin time [PT] and activated partial thromboplastin time [aPTT]), fibrin degradation products (FDP) and D‐Dimer concentrations. Results: PT and aPTT in donkeys were significantly (P < .05) shorter than those of horses. In contrast, FDP and D‐Dimer concentrations were significantly (P < .05) higher in donkeys than in horses. Conclusions and Clinical Importance: The coagulation parameters most commonly determined in equine practice are different in donkeys compared with horses. Thus, the use of normal reference ranges reported previously for healthy horses in donkeys might lead to a misdiagnosis of coagulopathy in healthy donkeys, and unnecessary treatments in sick donkeys. This is the first report of normal coagulation profile results in donkeys, and further studies are warranted to elucidate the physiological mechanisms of the differences observed between donkeys and horses.     

Thromboelastographic changes after gonadectomy in retired racing greyhounds

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; TEG(R) OR: 1.269, P=0.06; TEG(K) OR: 1.696, P=0.05; TEG(LY60) 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 (TEG(angle) OR: 0.903, P=0.03); and the strength of the clot (TEG(MA) OR: 0.833, P=0.03) were considered predictors of the outcome.     

Serial assessment of the coagulation status of dogs with immune-mediated haemolytic anaemia using thromboelastography

This study investigated the coagulation status of dogs with immune-mediated haemolytic anaemia (IMHA) over time. Thirty animals with primary IMHA were blood sampled on three occasions over a 5 day period and assays performed included prothrombin time, activated partial thromboplastin time, D-dimer and fibrinogen concentration, antithrombin activity and recalcified unactivated thromboelastography (TEG). Based on TEG, dogs with IMHA were significantly hypercoagulable vs. controls (P<0.001) and over the 5 day period, 3/4 of the TEG parameters reflected increased clotting kinetics (P ≤ 0.02). The 30 day survival of these patients was 80% and, at hospital admission, the TEG maximum amplitude (MA) was significantly higher in survivors than non-survivors (P=0.015). Each unit increase in MA was associated with an increased odds of 30 day survival of 1.13 (95%; CI 1.02-1.25). Based on TEG, most dogs with IMHA were hypercoagulable on admission and their clotting kinetics increased with time. Relative hypocoagulability identified by TEG at initial assessment was found to be a negative prognostic indicator.     

Thromboelastographic evaluation of hemostatic function in dogs with disseminated intravascular coagulation

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, alpha, 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.