Effects of hematocrit and red blood cell-independent viscosity on canine thromboelastographic tracings

Viscoelastic coagulation monitoring parameters in cats with acute arterial thromboembolism

BACKGROUND

Hypercoagulability has been documented in cats with cardiac disease. However, hemostatic parameters, including viscoelastic coagulation monitoring (VCM) have not been reported in cats with arterial thromboembolism (ATE).

HYPOTHESIS/OBJECTIVES

Compare VCM parameters in cats with acute cardiogenic ATE and in control cats.

ANIMALS

Sixteen cats with ATE and 30 control cats.

METHODS

Multicenter university-based prospective study. Cardiogenic ATE was diagnosed based on physical examination and by ultrasonographically-diagnosed left atrial enlargement. Viscoelastic coagulation monitor analysis, CBC, serum biochemistry profile and coagulation profile were performed at admission in cats with ATE. Analysis from healthy control cats was performed using blood collected by direct venipuncture. Our objective was comparison of VCM parameters clot time (CT), clot formation time (CFT), alpha angle (Angle), maximum clot formation (MCF), amplitude at 10 and 20 minutes (A10 and A20, respectively) and clot lysis index at 30 and 45 minutes (LI30 and LI45, respectively) between ATE and control cats.

RESULTS

Cats with ATE had a decreased angle compared to control cats, with a median (range) of 43° (30-48°) compared to 47° (14-59°; P = .01). The parameters A10, A20 and MCF were decreased in ATE cats compared to control cats with a median (range) of 19 units (8-32) compared to 22 units (6-38), 24.5 units (11-40) compared to 29 units (10-47) and 29.5 units (13-44) compared to 33.5 units (14-53), respectively (P = .01, .01 and .01, respectively). The parameters CT, CFT, LI30 and LI45 were similar between groups (P = .22, .09, .62 and .34, respectively).

CONCLUSIONS AND CLINICAL IMPORTANCE

Cats with cardiogenic ATE cats have VCM parameters consistent with hypocoagulability compared with healthy cats.

Prothrombin and activated partial thromboplastin times, thromboelastography, hematocrit, and platelet count in a feline hemorrhage/over-resuscitation model using lactated Ringer's solution or 6% tetrastarch 130/0.4

OBJECTIVE

To describe and compare prothrombin time (PT), activated partial thromboplastin time (aPTT), thromboelastography (TEG), HCT, and platelet count measurements in a hemorrhage/over-resuscitation model.

DESIGN

Randomized crossover study.

SETTING

University teaching hospital.

ANIMALS

Six cats.

INTERVENTIONS

Anesthetized cats underwent 3 treatments at 2-month intervals. The treatments were as follows: NHR-no controlled hemorrhage and sham resuscitation; LRS-controlled hemorrhage and lactated Ringer's solution (LRS) for resuscitation; and Voluven-controlled hemorrhage and 6% tetrastarch 130/0.4 for resuscitation. The LRS and Voluven were administered at 60 and 20 mL/kg/h, respectively, for 120 minutes. Blood samples were drawn for PT, aPTT, TEG, HCT, and platelet count measurements at a healthy check (T - 7d), after controlled hemorrhage (T0), at 60 and 120 minutes of resuscitation (T60 and T120), and at 24 hours after completion of resuscitation (T24h). Data were analyzed using a general linear mixed model approach (significance was P < 0.05).

MEASUREMENTS AND MAIN RESULTS

Total median blood loss (controlled hemorrhage and blood sampling from T0 to T120) at T120 was 11.4, 31.0, and 30.8 mL/kg for NHR, LRS, and Voluven, respectively. PT and aPTT during LRS and Voluven were prolonged at T60 and T120 compared to NHR (P < 0.001). On TEG, the reaction time, kinetic time, and alpha-angle were within reference intervals for cats at all time points in all treatments, while maximum amplitude was less than the reference interval (40 mm) at T0, T60, and T120 during Voluven and at T60 and T120 during LRS compared to NHR (both P < 0.001). The HCT and platelet count were significantly lower at T60 and T120 during LRS and Voluven compared to NHR (P < 0.001).

CONCLUSIONS

Hypocoagulopathy was observed during hemorrhage and liberal fluid resuscitation. Prolongation of PT and aPPT and decreased clot strength may have been caused by hemodilution and platelet loss.

Evaluation of coagulation and platelet activation state and function in heartworm-infected dogs

BACKGROUND

Enhanced platelet responses have been demonstrated in heartworm-infected (HWI) dogs; however, the cause and clinical implications of altered platelet function have not been fully elucidated.

OBJECTIVE

This study evaluated platelet function in HWI dogs.

METHODS

Anticoagulated whole blood collected from eight HWI and eight uninfected dogs was evaluated using turbidometric platelet aggregometry, a platelet function analyzer (PFA-100), a total thrombus analysis system (T-TAS), tissue factor-activated and tissue plasminogen activator modified thromboelastography (TF- and tPA-TEG), CBC, von Willebrand Factor activity, and fibrinogen concentrations. Platelet activation state and the presence of reticulated platelets were assessed via flow cytometric expression of P-selection (CD-62P) and thiazole orange staining.

RESULTS

Platelet aggregation responses to adenosine diphosphate (ADP, 10 μM) or collagen (20 μg/mL), PFA-100 closure times, and T-TAS occlusion times did not differ between groups. TEG values TF-R, tPA-R, TF-K, and TF-LY60 were decreased (P = .025, P = .047, P  = .038, P  = .025) and TF-MA, tPA-MA, TF-G, tPA-G and TF-alpha angle were increased (P  < .04) in HWI dogs. HWI dogs had higher fibrinogen concentrations (465.6 ± 161 mg/dL vs 284.5 ± 38 mg/dL, P  = .008) and eosinophil counts (0.686 ± 0.27 × 103/μL vs 0.267 ± 0.20 × 103/μL, P  = .003). There was no difference in hematocrit, activation state, or percent of reticulated platelets. Non-activated reticulated platelets exhibited higher CD62P expression compared with mature platelets.

CONCLUSIONS

Chronic canine heartworm disease was accompanied by hypercoagulability, hyperfibrinogenemia, and decreased fibrinolysis. Enhanced platelet activation was not identified in this group of HWI dogs.

Standard tests of haemostasis do not predict elevated thromboelastographic maximum amplitude, an index of hypercoagulability, in sick dogs

OBJECTIVES

To compare standard tests of haemostasis in hypercoagulable and normocoagulable sick dogs as identified by thromboelastography.

MATERIALS AND METHODS

We compared prothrombin time, activated partial thromboplastin time, D-dimers, packed red blood cell volume and platelet counts in client-owned sick dogs with hypercoagulable (n = 36) and normocoagulable (n = 35) states as identified by thromboelastography maximum amplitude above or within the established reference interval, respectively.

RESULTS

Seventy-one dogs were included. Thirty-six dogs were hypercoagulable and 35 were normocoagulable on thromboelastography. Using multivariable linear models, prothrombin time, activated partial thromboplastin time and D-dimers were not associated with hypercoagulability. Platelet counts and packed red blood cell volume were significantly associated with hypercoagulability.

CLINICAL SIGNIFICANCE

Prothrombin time, activated partial thromboplastin time and D-dimers were not useful in the identification of hypercoagulability in dogs as defined by thromboelastography.

INVESTIGATION OF A POINT-OF-CARE VISCOELASTIC COAGULATION MONITOR AND ITS COMPARISON TO THROMBOELASTOGRAPHY IN CLINICALLY HEALTHY AFRICAN ELEPHANTS (LOXODONTA AFRICANA)

Elephant endotheliotropic herpesvirus (EEHV) can induce fatal hemorrhagic disease (HD) in African elephants (Loxodonta africana). Once clinical signs develop, progression is rapid, even with aggressive treatment. There is a critical need to develop point-of-care diagnostic tests to aid in identification of EEHV-HD prior to the onset of overt clinical signs. Study objectives were to investigate a novel, point-of-care viscoelastic coagulation monitor (VCM Vet), compare the results to thromboelastography (TEG), and report traditional hemostatic analytes in adult African elephants. Whole blood was collected from seven clinically healthy elephants (four females and three males, 18-47 yr) and analyzed in duplicate via VCM Vet and kaolin-activated TEG 1-3 and 30 min following collection, respectively. Separated plasma was frozen for ancillary coagulation testing. Both analyses generated quantifiable clotting reactions with variables (median [range]) describing clot formation rate (VCM Vet, clot time = 682 s [530-987 s], clot formation time = 244 s [186-744 s], Alpha = 40° [14-47°]; TEG, reaction time = 6.2 min [3.7-11.8 min], kinetic time = 1.3 min [0.9-2.6 min], Alpha = 70° [57-77°]), clot strength (VCM Vet, maximum clot formation = 34 units [20-45 units]; TEG, maximum amplitude = 75 mm [69-80 mm], shear elastic modulus strength = 14.7 Kdynes/s [11.3-19.5 Kdynes/s]), and clot lysis (VCM Vet, lysis index at 30 min = 100% [100-99%], lysis index at 45 min = 98% [95-100%]; TEG, lysis index at 30 min = 0% [0-0.4%], lysis index at 60 min = 1.4% [0-2.6%]) recorded. Additional testing (median [range]) included D-dimer concentration (33 ng/ml [28-94 ng/ml]), prothrombin time (12.4 s [12.2-13.2 s]), activated partial thromboplastin time (17.2 s [14.2-18.8 s]), and fibrinogen concentration (297 [282-383] mg/dL). Tracings generated by VCM Vet and TEG were clinically similar, and there was visual agreement and minimal difference between quantitative variables for duplicate tests. VCM Vet is a promising, user-friendly tool for use in identification and management of coagulopathies in African elephants.

Hemoglobin Concentration Impacts Viscoelastic Hemostatic Assays in ICU Admitted Patients

OBJECTIVES

Low hemoglobin concentration impairs clinical hemostasis across several diseases. It is unclear whether hemoglobin impacts laboratory functional coagulation assessments. We evaluated the relationship of hemoglobin concentration on viscoelastic hemostatic assays in intracerebral hemorrhage (ICH) and perioperative patients admitted to an ICU.

DESIGN

Observational cohort study and separate in vitro laboratory study.

SETTING

Multicenter tertiary referral ICUs.

PATIENTS

Two acute ICH cohorts receiving distinct testing modalities: rotational thromboelastometry (ROTEM) and thromboelastography (TEG), and a third surgical ICU cohort receiving ROTEM were evaluated to assess the generalizability of findings across disease processes and testing platforms. A separate in vitro ROTEM laboratory study was performed utilizing ICH patient blood samples.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Relationships between baseline hemoglobin and ROTEM/TEG results were separately assessed across patient cohorts using Spearman correlations and linear regression models. A separate in vitro study assessed ROTEM tracing changes after serial hemoglobin modifications from ICH patient blood samples. In both our ROTEM (n = 34) and TEG (n = 239) ICH cohorts, hemoglobin concentrations directly correlated with coagulation kinetics (ROTEM r: 0.46; p = 0.01; TEG r: 0.49; p < 0.0001) and inversely correlated with clot strength (ROTEM r: -0.52, p = 0.002; TEG r: -0.40, p < 0.0001). Similar relationships were identified in perioperative ICU admitted patients (n = 121). We continued to identify these relationships in linear regression models. When manipulating ICH patient blood samples to achieve lower hemoglobin concentrations in vitro, we similarly identified that lower hemoglobin concentrations resulted in progressively faster coagulation kinetics and greater clot strength on ROTEM tracings.

CONCLUSIONS

Lower hemoglobin concentrations have a consistent, measurable impact on ROTEM/TEG testing in ICU admitted patients, which appear to be artifactual. It is possible that patients with low hemoglobin may appear to have normal viscoelastic parameters when, in fact, they have a mild hypocoagulable state. Further work is required to determine if these tests should be corrected for a patient's hemoglobin concentration.

Point-of-care global coagulation assay parameters in normal dogs and dogs with primary immune-mediated hemolytic anemia

OBJECTIVE

To compare viscoelastic parameters between healthy control dogs and dogs with primary immune-mediated hemolytic anemia (pIMHA) using a new, point-of-care viscoelastic coagulation monitor (VCM).^a DESIGN: Retrospective study from 2017 to 2021.

SETTING

Three regional private referral centers.

ANIMALS

Eighteen client-owned dogs with pIMHA and 33 healthy control dogs. pIMHA dogs were defined based on established criteria.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Medical records of dogs with pIMHA and VCM performed at diagnosis from 2017 to 2021 and apparently healthy control dogs voluntarily enrolled in the blood donor program from 2017 to 2018 were reviewed. For the healthy control dogs, consent was obtained to perform VCM in addition to traditional screening. Compared to healthy control dogs, dogs with pIMHA had mean VCM parameters consistent with hypercoagulability, demonstrated by lower mean (SD) clot formation time (108 s [30] vs 233 s [55]; P < 0.0001), higher mean alpha angle (62 degrees [6] vs 52 degrees [6]; P < 0.0001), higher mean maximum clot formation (49 VCM units [11] vs 32 VCM units [5]; P < 0.0001), higher mean amplitude at 10 minutes (40 VCM units [11] vs 19 VCM units [3]; P < 0.0001), and higher mean amplitude at 20 minutes (47 VCM units [11] vs 25 VCM units [4]; P < 0.0001). pIMHA dogs also had significantly higher median (interquartile range) lysis index at 30 minutes (100% [100-100] vs 98% [90-100]; P < 0.0001). When compared to 3 established normal canine reference intervals, dogs with pIMHA had a significantly higher proportion of VCM variables (48%-57%) consistent with hypercoagulability, and a significant percentage of pIMHA dogs (78%-89%) had VCM tracings consistent with hypercoagulability overall, irrespective of the interval utilized for interpretation.

CONCLUSIONS

This study demonstrates hypercoagulability in dogs with pIMHA when compared to healthy control dogs using VCM. Prospective evaluation is warranted to further characterize these findings as well as to evaluate their clinical impact.

Effectiveness of aspirin vs. clopidogrel in dogs with immune mediated haemolytic anaemia evaluated by serial thromboelastography and platelet mapping

Most dogs with immune mediated haemolytic anaemia (IMHA) are hypercoagulable, as measured by thromboelastography (TEG). Thromboelastography-platelet mapping (TEG-PM) has been used to assess platelet function in human patients treated with aspirin or clopidogrel. The aim of this study was to compare platelet thromboxane A₂-receptor inhibition (TXA_2-RI) and platelet adenosine diphosphate (ADP)-receptor inhibition (ADP-RI) as measured by TEG-PM in dogs with primary IMHA receiving aspirin or clopidogrel to determine if TEG-PM might be useful to monitor treatment. Eighteen client-owned dogs with IMHA were enroled in a prospective double blinded study. Dogs were randomised to receive aspirin or clopidogrel in addition to standard therapy. Thromboelastography was measured before, and 1 and 4 days after commencing treatment. Thromboelastography-PM was performed on days 1 and 4. Non-responders were defined as < 50 % platelet thromboxane A₂-receptor inhibition (TXA_2-RI) in the aspirin group and < 50 % platelet adenosine diphosphate (ADP)-receptor inhibition (ADP-RI) in the clopidogrel group, on day 4. Mean platelet TXA₂-RI and platelet ADP-RI were not significantly different between groups at any timepoint (P > 0.05). The overall mean percentage inhibition of TXA₂-receptor was 25 % (aspirin 33 %, clopidogrel 15 %), and of ADP-receptor was 82 % (aspirin 83 %, clopidogrel 80 %). On day 4, 6/9 dogs (66 %) in the aspirin group and 2/8 dogs (25 %) in the clopidogrel group were non-responders (P = 0.086). Two dogs defined as responders based on TEG-PM developed thromboembolism. Overall, there was no significant difference in efficacy between aspirin and clopidogrel based on measurement of receptor inhibition using TEG-PM (P > 0.05), and routine TEG was not reliable for monitoring treatment response in dogs with IMHA. In some dogs, there was a discrepancy between TEG-PM results and clinical response. Further investigation of TEG-PM use in dogs, including its usefulness to monitor treatment response and adjust treatment in individual dogs and any effect of anaemia, is warranted.

Evaluation of the Effect of Storage Time on ROTEM S® Parameters in Healthy and Ill Dogs

Simple Summary

Bleeding disorders can cause life-threatening illness in dogs. The need for fast recognition and diagnosis of these conditions is therefore of the utmost importance to have a positive impact on the patients’ survival. In the past decade, the use of viscoelastic testing for rapid assessment of global haemostasis has gained popularity. However, the most reliable time for testing after blood collection has not been determined. For this reason, blood samples were taken from healthy client-/staff-owned dogs and repeated measurements were performed at three different time points (10 min, 30 min, and 70 min after blood collection). Additionally, a group of currently ill patients was included and Ex-TEM S measurements were performed at the same three timepoints. We found that there was a significant change of results over time, suggesting the need for time-specific reference intervals. Which of these time points reflects the “true” coagulation status of our patients currently remains unknown.

Abstract

Viscoelastic testing as a bedside test to assess global haemostasis has gained popularity in the past decade, with rotational thromboelastometry (ROTEM) and thromboelastography (TEG) being the two commonly used devices. TEG studies suggest analysis 30 min after blood sampling. However, the reproducibility of results over time for ROTEM analysis using lyophilized samples in dogs has not been established. In this study, we investigated the influence of time on viscoelastic testing, using 33 healthy staff-/client-owned dogs for blood sampling and repeated measurements of ROTEM tracings at three different time points after blood collection. Additionally, a group of 21 hospitalized patients with suspected coagulation disorders were included to investigate whether stability over time was comparable between healthy and ill dogs. We demonstrated a significant difference of ROTEM tracings over time, with a tendency towards hypocoagulability over time. These changes do have a clinical relevance as they exceed reference intervals and could therefore lead to erroneous conclusions about a patient’s coagulation status. Therefore, time-specific reference intervals are proposed and presented in this publication.

Lipid and Haematologic Profiling of Regular Blood Donors Revealed Health Benefits

Background

Objective

Materials and Methods

Results

Conclusion

Aberrant inflammation in rat pregnancy leads to cardiometabolic alterations in their offspring and intrauterine growth restriction in the F2 generation

Children of women with pre-eclampsia have increased risk of cardiovascular (CV) and metabolic disease in adult life. Furthermore, the risk of pregnancy complications is higher in daughters born to women affected by pre-eclampsia than in daughters born after uncomplicated pregnancies. While aberrant inflammation contributes to the pathophysiology of pregnancy complications, including pre-eclampsia, the contribution of maternal inflammation to subsequent risk of CV and metabolic disease as well as pregnancy complications in the offspring remains unclear. Here, we demonstrate that 24-week-old female rats (F1) born to dams (F0) exposed to lipopolysaccharide (LPS) during pregnancy (to induce inflammation) exhibited mild systolic dysfunction, increased cardiac growth-related gene expression, altered glucose tolerance, and coagulopathy; whereas male F1 offspring exhibited altered glucose tolerance and increased visceral fat accumulation compared with F1 sex-matched offspring born to saline-treated dams. Both male and female F1 offspring born to LPS-treated dams had evidence of anemia. Fetuses (F2) from F1 females born to LPS-treated dams were growth restricted, and this reduction in fetal growth was associated with increased CD68 positivity (indicative of macrophage presence) and decreased expression of glucose transporter-1 in their utero-placental units. These results indicate that abnormal maternal inflammation can contribute to increased risk of CV and metabolic disease in the offspring, and that the effects of inflammation may cross generations. Our findings provide evidence in support of early screening for CV and metabolic disease, as well as pregnancy complications in offspring affected by pre-eclampsia or other pregnancy complications associated with aberrant inflammation.

Comparison of healthy blood donor Greyhounds and non-Greyhounds using a novel point-of-care viscoelastic coagulometer

OBJECTIVE

To measure and compare viscoelastic coagulation in 2 canine blood donor populations using a novel, point-of-care device (VCM Vet Analyzer, VCM).

DESIGN

Cohort study.

SETTING

Academic and commercial veterinary blood banks.

ANIMALS

Non-Greyhounds from community-based blood donor program and Greyhounds from a blood bank colony.

INTERVENTION

Blood was collected from all dogs via direct venipuncture for a complete hemogram, biochemistry, and point-of-care viscoelastic coagulation.

MEASUREMENT AND MAIN RESULTS

All biochemical measurements for all dogs in Group NG (n = 38, non-Greyhounds) and Group G (n = 53, Greyhounds) were within local reference intervals. Hematology data showed significant statistical differences between groups in hemoglobin, RBC, platelet, and WBC concentrations. Group G demonstrated lower maximum clot firmness (MCF) with 17 VCM units (26 VCM units in Group NG), increased lysis with 30 VCM units at 30 minutes (LI30) and 27 VCM units at 45 minutes (LI45) (86 VCM units LI30 and 85 VCM units LI45 in Group NG), and decreased amplitude of 13 VCM units 10 minutes (A10) after clot time (CT) and 6 VCM units 20 minutes after CT (A20) (18 VCM units [A10] and 22 VCM units [A20] in Group NG).

CONCLUSION

This study found differences between healthy Greyhound and non-Greyhound blood donors in measures of clot strength and fibrinolysis as measured by the VCM. Whereas Greyhound have unique hematologic and hemostatic profiles, these measured viscoelastic differences are important to note prior to and following surgical intervention to aid in clinical decision-making if bleeding complications develop.

Use of Thromboelastography in Clinical Practice

Viscoelastic testing, such as thromboelastography or thromboelastometry, is performed on whole-blood samples, which include both soluble plasma factors as well as blood cells and platelets bearing tissue factor and phospholipid. This methodology allows identification of fibrinolysis and can provide analysis of platelet function. Viscoelastic testing has become increasingly accessible and popular in emergency and critical care settings in recent years and can provide important information for the diagnosis and management of patients with hemostatic disorders. This article discusses the principles and interpretation of viscoelastic testing, application to small animal emergency and critical care medicine, and potential advantages and disadvantages.

Disturbances of the hemostasis system and expression of inflammatory reaction in patients with new coronaviral pneumonia

Disorders of the hemostatic system and inflammation play a key role in the pathogenesis of new coronavirus pneumonia (NCP), determining its course and outcome. To study the dynamics of the state of the hemostasis system and the severity of the acute phase response in patients with new coronavirus pneumonia. We determined APTT, prothrombin time (PT), fibrinogen (F), D-dimers (D-d), antitrombin III (AT III), C-reactive protein (CRP), platelet count in 22 patients. In 49 patients, the viscoelastic properties of a blood clot were studied by thromboelastography (TEG) with koalin. The age of the patients ranged from 40 to 77 years. According to CT, the severity of 100% cases corresponded to CT2-CT3. Acute respiratory failure (ARF) was diagnosed in 16 patients. A control group included 25 apparently healthy subjects. During hospitalization, patients with NCP were characterized by: an increase in the concentration of D-d, CRP, Fg, lengthening of APTT and PT, ATIII activity and platelet count not differing from the normal range. 10 days after hospitalization and against the background of ongoing therapy, patients with NCP showed positive dynamics in the hemostasiological profile and the severity of the inflammatory response. Thromboelastography indices in patients with LCP did not differ from control values both at hospitalization and on day 10.Thus, in patients with novel coronavirus pneumonia, an increased prothrombotic activity and a pronounced inflammatory response are recorded. Against the background of treatment, there is a positive dynamics in both the coagulation status and the inflammatory response. Additional studies are needed to determine the diagnostic capabilities of thromboelastography in patients with NCP.

Blood loss and coagulation profile in pregnant and non-pregnant queens undergoing elective ovariohysterectomy

OBJECTIVES

The aims of this study were to determine if there is increased risk of intraoperative bleeding in pregnant cats undergoing elective ovariohysterectomy (OHE), and to compare coagulation in queens in various stages of estrus and pregnancy subjected to elective OHE using a whole-blood viscoelastic assay.

METHODS

Intraoperative blood loss was compared between non-pregnant and pregnant cats undergoing elective OHE. Viscoelastic evaluations of whole blood drawn pre- and postoperatively were performed using a point-of-care device measuring clot time (CT), clot formation time (CFT), alpha angle, maximum clot formation (MCF), amplitude at 10 and 20 mins (A10 and A20, respectively), and lysis index at 30 and 45 mins after MCF (LI30 and LI45, respectively).

RESULTS

One hundred and ninety-three cats underwent OHE by a ventral midline approach. Median blood loss was greater for pregnant cats (2.0 ml, range <0.5-13 ml) than non-pregnant cats (<0.5 ml, range <0.5-15 ml; P <0.0001). Preoperatively, pregnant cats had a shorter median CFT (165 s vs 190.5 s), increased median A10 (31 from 25.5 VCM units) and A20 (38 from 35 VCM units), and a lower median LI45 (99% from 100%) than non-pregnant cats. Postoperatively, A10 and A20 increased, and LI30 and LI45 decreased in both non-pregnant and pregnant queens. In pregnant queens, mean CT also increased postoperatively.

CONCLUSIONS AND RELEVANCE

Pregnant cats were relatively hypercoagulable and had an increased rate of clot lysis than non-pregnant cats. Intraoperative blood loss was increased in pregnant vs non-pregnant cats, but no clinically relevant bleeding conditions occurred.

Systematic review of viscoelastic testing (TEG/ROTEM) in obstetrics and recommendations from the women's SSC of the ISTH

Thromboelastography (TEG) and rotational thromboelastometry (ROTEM) are point-of-care viscoelastic devices that use whole blood samples to assess coagulation and fibrinolysis. These devices have been studied extensively in cardiac surgery, but there is limited robust evidence supporting its use in obstetrics. The hesitancy toward its routine use in obstetrics may be due to the current lack of randomized controlled trials and large observational studies. The study aims to systematically review studies that investigated TEG/ROTEM use in pregnancy or peripartum, and to provide recommendations for future studies to fill current research gaps. We performed a systematic review of studies on viscoelastic testing in obstetrics. Included studies were original research, used TEG or ROTEM during pregnancy or peripartum, and published in English. Ninety-three studies, spanning 31 years from 1989 to 2020 and with a total of 32,817 participants, were included. Sixty-two (66.7%) of the studies used TEG and 31 (33.3%) used ROTEM. To date, there are a total of two randomized controlled trials on TEG/ROTEM use in obstetrics. ROTEM may be used to guide transfusion therapy for postpartum hemorrhage. TEG and ROTEM can detect the hypercoagulable changes associated with pregnancy. Variability between study protocols and results suggests the need for future large prospective high-quality studies with standardized protocols to investigate the utility of TEG/ROTEM in assessing risk for thrombosis and hemorrhage as well as in guiding prophylaxis and treatment in obstetric patients. This review identifies the gaps and provides concrete recommendations for future studies to fill those gaps.

Haemostatic changes associated with fluid resuscitation in canine parvoviral enteritis

The haemostatic status of dogs with canine parvovirus (CPV) enteritis, within 24 h of admission after initial fluid administration, has been described previously, but the haemostatic status at admission and after standard fluid resuscitation, as well as after initial fluid redistribution, has not been investigated previously. The objective of this study was to characterise the haemostatic status at admission and describe the effect of crystalloid fluid resuscitation on haemostatic variables in dogs with CPV enteritis. Twenty-seven client-owned, hospitalised dogs with confirmed natural CPV infection and 15 healthy age-matched controls were included in a prospective, observational clinical study. The volume of resuscitation fluid, haematocrit (HCT), platelet count, thromboelastography (TEG) variables, antithrombin (AT) activity, fibrinogen- and C-reactive protein (CRP) concentrations were measured in all dogs at admission, after fluid resuscitation and, in 10 dogs, after receiving an additional 3 hours of maintenance-rate crystalloid fluids. For the CPV group at admission, the median TEG reaction time (R) and maximum amplitude (MA) or clot strength, as well as the median HCT, fibrinogen and CRP concentrations, were significantly increased compared to the controls. After fluid resuscitation, median R was significantly shorter, MA significantly increased and HCT and AT activity significantly decreased compared to admission values. The haemostatic variables remained unchanged after 3 h of maintenance-rate crystalloid therapy. The increased clot strength present in dogs with CPV enteritis at admission was exacerbated after fluid resuscitation and persisted for hours after large-volume crystalloid fluid administration.

Effect of packed red blood cell transfusion on thromboelastographic tracings in dogs with naturally occurring anemia

OBJECTIVE

To assess the effect of packed RBC (pRBC) transfusion on thromboelastographic (TEG) tracings in dogs with naturally occurring anemia.

ANIMALS

22 clinically anemic dogs that received a pRBC transfusion.

PROCEDURES

For each dog, a blood sample was collected before and within 3 hours after completion of the pRBC transfusion for a CBC, nonactivated TEG analysis, and measurement of blood viscosity. Wilcoxon signed rank tests were used to compare CBC, viscosity, and TEG variables between pretransfusion and posttransfusion blood samples. Multivariable linear regression was used to assess the effects of pretransfusion-posttransfusion changes in Hct, WBC count, and platelet count on changes in TEG variables.

RESULTS

Median posttransfusion Hct (21%; range, 13% to 34%) was significantly greater than the median pretransfusion Hct (12.5%; range, 7% to 29%). Packed RBC transfusion was associated with a median increase in Hct of 6.2% (range, 1.2% to 13%). Maximum amplitude significantly decreased from 74.9 to 73.8 mm and clot strength significantly decreased from 14,906 to 14,119 dynes/s after pRBC transfusion. Blood viscosity significantly increased, whereas platelet and WBC counts significantly decreased after transfusion. Multivariable linear regression revealed that pretransfusion-posttransfusion changes in Hct, WBC count, and platelet count were not associated with changes in TEG variables.

CONCLUSIONS AND CLINICAL RELEVANCE

Results indicated that pRBC transfusion had only small effects on the TEG tracings of hemodynamically stable dogs. Therefore, large changes in TEG tracings following pRBC transfusion are unlikely to be the result of the transfusion and should be investigated further.

Postoperative thrombocytosis and thromboelastographic evidence of hypercoagulability in dogs undergoing splenectomy for splenic masses

OBJECTIVE

To determine the frequency and severity of thrombocytosis and thromboelastographic evidence of hypercoagulability during the first 2 weeks after splenectomy in dogs with splenic masses and to investigate relationships between platelet counts and thromboelastography values.

ANIMALS

34 dogs undergoing splenectomy for splenic masses.

PROCEDURES

Blood samples for platelet counts and thromboelastography were obtained at induction of anesthesia (day 0) prior to splenectomy and on days 2, 7, and 14.

RESULTS

Mean platelet counts were 167.9 × 10³/μL, 260.4 × 10³ μ/L, 715.9 × 10³/μL, and 582.2 × 10³/μL on days 0, 2, 7, and 14, respectively, and were significantly higher at all postoperative assessment points than on day 0. Thrombocytosis was observed in 3% (1/34), 6% (2/33), 81% (21/26), and 69% (18/26) of dogs on days 0, 2, 7, and 14. Platelet counts > 1,000 × 10³/μL were observed in 1 dog on day 2 and in 5 dogs on day 7. One or more thromboelastography values suggestive of hypercoagulability were observed in 45% (15/33), 84% (26/31), 89% (24/27), and 84% (21/25) of dogs on days 0, 2, 7, and 14. At each assessment point, higher platelet counts were correlated with thromboelastography values suggestive of hypercoagulability.

CONCLUSIONS AND CLINICAL RELEVANCE

Marked thrombocytosis and thromboelastography values suggestive of hypercoagulability were common during the first 2 weeks after splenectomy for the dogs of this study. If present, hypercoagulability could increase the risk for development of postsplenectomy thrombotic conditions such as portal system thrombosis and pulmonary thromboembolism.

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

OBJECTIVE

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.

ANIMALS

Two healthy adult mixed-breed dogs.

PROCEDURES

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.

RESULTS

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.

CONCLUSIONS AND CLINICAL RELEVANCE

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.

Platelet Function and Therapeutic Applications in Dogs: Current Status and Future Prospects

Significant progress has been made in the functional characterization of canine platelets in the last two decades. The role of canine platelets in hemostasis includes their adhesion to the subendothelium, activation, and aggregation, leading to primary clot formation at the site of injury. Studies on canine platelet function and advancements in laboratory testing have improved the diagnosis and understanding of platelet-related disorders as well as the knowledge of the mechanisms behind these diseases. This review focuses on the most recent discoveries in canine platelet structure, function, and disorders; and discusses the efficacy of various tests in the diagnosis of platelet-related disorders. With the relatively recent discovery of angiogenetic and reparative effects of growth factors found in platelets, this review also summarizes the use of canine platelet-rich plasma (PRP) alone or in association with stem cells in regenerative therapy. The characterization of proteomic and lipidomic profiles and development of platelet gene therapy in veterinary species are areas of future study with potential for major therapeutic benefits.

Determination of reference intervals for single vial rotational thromboelastometry (ROTEM) parameters and correlation with plasmatic coagulation times in 49 clinically healthy dogs

The objectives of this prospective study were determination of reference intervals (RI) for rotational thromboelastometry (ROTEM) parameters in single use reagents and to evaluate correlations between plasmatic coagulation times and ROTEM parameters. Blood was sampled from a jugular vein in 49 client-owned healthy dogs and ex-tem S, in-tem S, fib-tem S and ap-tem S parameters, prothrombin time (PT), activated partial thromboplastin time (aPTT), fibrinogen, haematology, blood chemistry and venous blood gas analysis was performed. Determination of RI was performed using Excel add-in Reference Value Advisor and correlations between PT, aPTT and fibrinogen with selected ROTEM parameters were determined by Spearman correlation. Ex-tem S maximum clot firmness (MCF) RI are smaller compared to RI in people and liquid ex-tem in dogs while maximum lysis was comparable to those in people but smaller than previously reported in dogs. A strong correlation was found between fibrinogen measured by Clauss and fib-tem S and in-tem S MCF (r = 0.541, P < .001 and r = 0.610, P < .001, respectively). PT showed a significant but moderate correlation with ex-tem S CT (r = 0.340, P = .030), in-tem S CFT (r = 0.433, P = .003), fib-tem S CT (r = 0.426, P = .009) and ap-tem S CT (r = 0.354, P = .015) while aPTT was not significantly correlated with any of the evaluated parameters. In conclusion, this study provides single use reagent ROTEM parameter RIs that are different from RI determined with liquid reagents. Significant correlations between fibrinogen concentrations measured by Clauss and clot firmness of fib-tem S and in-tem S profiles and between PT and clotting times of all reagents were identified.

A review of hyperfibrinolysis in cats and dogs

The fibrinolytic system is activated concurrently with coagulation; it regulates haemostasis and prevents thrombosis by restricting clot formation to the area of vascular injury and dismantling the clot as healing occurs. Dysregulation of the fibrinolytic system, which results in hyperfibrinolysis, may manifest as clinically important haemorrhage. Hyperfibrinolysis occurs in cats and dogs secondary to a variety of congenital and acquired disorders. Acquired disorders associated with hyperfibrinolysis, such as trauma, cavitary effusions, liver disease and Angiostrongylus vasorum infection, are commonly encountered in primary care practice. In addition, delayed haemorrhage reported in greyhounds following trauma and routine surgical procedures has been attributed to a hyperfibrinolytic disorder, although this has yet to be characterised. The diagnosis of hyperfibrinolysis is challenging and, until recently, has relied on techniques that are not readily available outside referral hospitals. With the recent development of point-of-care viscoelastic techniques, assessment of fibrinolysis is now possible in referral practice. This will provide the opportunity to target haemorrhage due to hyperfibrinolysis with antifibrinolytic drugs and thereby reduce associated morbidity and mortality. The fibrinolytic system and the conditions associated with increased fibrinolytic activity in cats and dogs are the focus of this review article. In addition, laboratory and point-of-care techniques for assessing hyperfibrinolysis and antifibrinolytic treatment for patients with haemorrhage are reviewed.

A prospective evaluation of oral Yunnan Baiyao therapy on thromboleastographic parameters in apparently healthy dogs

OBJECTIVE

To determine the effect of Yunnan Baiyao (YB) on hemostatic parameters measured by thromboelastography (TEG) in healthy dogs administered 1 capsule of YB orally twice daily for 1 week.

DESIGN

Prospective study of client-owned dogs at a small animal specialty hospital.

SETTING

Private referral center.

ANIMALS

Eighteen client-owned adult dogs weighing at least 15 kg.

INTERVENTIONS

Dogs had a baseline TEG performed and then each dog was administered 1 capsule of YB twice daily by mouth for 1 week and the TEG was reevaluated. Any side effects attributed to YB were noted at this time.

MEASUREMENTS AND MAIN RESULTS

All 18 enrolled dogs completed the study. Dogs that received 1 capsule (250 mg/capsule) of YB orally twice daily had significantly increased G as well as A30 and A60 values. There was also a significantly decreased LY30 and LY60 values after 1 week. The YB appeared well tolerated as only one dog developed mild diarrhea.

CONCLUSIONS

The results of this study suggest that YB at 1 capsule orally twice daily in healthy medium to large breed dogs increases the strength of the clot as measured by TEG and that YB was apparently well tolerated in the study population reported here. Larger prospective studies in different disease states are warranted to further evaluate these preliminary findings.

Influence of immune-mediated hemolytic anemia on flow velocities in the portal vein and caudal vena cava measured by use of pulsed-wave Doppler ultrasonography in dogs

OBJECTIVE To compare blood flow velocities of the portal vein (PV) and caudal vena cava (CVC) measured by use of pulsed-wave Doppler ultrasonography in clinically normal dogs and dogs with primary immune-mediated hemolytic anemia (IMHA). ANIMALS 11 client-owned dogs admitted to a veterinary teaching hospital for management of primary IMHA and 21 staff- or student-owned clinically normal dogs. PROCEDURES Flow velocities in the PV and CVC at the porta hepatis were evaluated in conscious unsedated dogs with concurrent ECG monitoring; evaluations were performed before dogs with IMHA received heparin or blood transfusions. Three measurements of peak velocity at end expiration were obtained for each vessel, and the mean was calculated. Results were compared between IMHA and control groups. RESULTS Mean ± SD blood flow velocity in the CVC differed between control (63.0 ± 18.6 cm/s) and IMHA (104 ± 36.9 cm/s) groups. Variance in dogs with IMHA was significantly greater than that for the clinically normal dogs. No significant difference in blood flow velocity in the PV was detected between IMHA and control dogs. CONCLUSIONS AND CLINICAL RELEVANCE Higher blood flow velocities were detected by use of pulsed-wave Doppler ultrasonography in the CVC of dogs with naturally occurring IMHA and may be used to predict anemia in patients suspected of having IMHA.

Development of a fibrinolysis assay for canine plasma

Unbalanced coagulation and fibrinolysis leads to hemorrhage or thrombosis. Thromboelastography has been used to characterize hypo- and hyper-fibrinolysis in dogs, however the technique requires specialized instrumentation and proprietary reagents that limit its availability. The aim of this study was to develop a simple microplate method for assessment of fibrinolysis in canine plasma. Plasma from healthy dogs was mixed in a microwell plate with tissue factor, calcium, phospholipid and tissue plasminogen activator. Light absorbance was measured at regular intervals until return to baseline. Peak optical density (milli-absorption units, mAU), formation velocity (mAU/s), lysis velocity (mAU/s) and area under the curve (mAU.s) were calculated. The influence of potential interferents, variation in fibrinogen and ex vivo addition of heparin and aminocaproic acid on assay performance was determined. Inter-day coefficients of variation were ≤15% for all variables. Bilirubin≤1.88mg/dL and hemoglobin≤0.09mg/dL did not interfere with assay variables. Aminocaproic acid (40μg/mL) and heparin (0.125U/mL) caused almost complete inhibition of fibrinolysis and coagulation, respectively. All variables except lysis velocity (R²=0.08) were associated with fibrinogen concentration (R²>0.8). This assay showed acceptable performance characteristics for measurement of fibrinolysis in normal canine plasma. The assay utilizes small volume citrate plasma samples and readily available instrumentation and reagents, is not influenced by mild to moderate hemolysis or icterus and detects the presence of fibrinolysis inhibitors.

Viscoelastic Monitoring to Guide Hemostatic Resuscitation in Liver Transplantation Surgery

Coagulopathic bleeding must be anticipated during liver transplantation (LT) surgery. Patients with end-stage liver disease (ESLD) often present with disease-related hematologic disturbances, including the loss of hepatic procoagulant and anticoagulant clotting factors and thrombocytopenia. Transplantation surgery itself presents additional hemostatic changes, including hyperfibrinolysis. Viscoelastic monitoring (VEM) is often used to provide targeted, personalized hemostatic therapies for complex bleeding states including cardiac surgery and major trauma. The use in these coagulopathic conditions led to its application to LT, although the mechanisms of coagulopathy in these patients are quite different. While VEM is often used during transplant surgeries in Europe and North America, evidence supporting its use is limited to a few small clinical studies. The theoretical and clinical applications of the standard and specialized VEM assays are discussed in the setting of LT and ESLD.

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.

Targeted Thromboelastographic (TEG) Blood Component and Pharmacologic Hemostatic Therapy in Traumatic and Acquired Coagulopathy

Trauma-induced coagulopathy (TIC) is a recently described condition which traditionally has been diagnosed by the common coagulation tests (CCTs) such as prothrombin time/international normalized ratio (PT/INR), activated partial thromboplastin time (aPTT), platelet count, and fibrinogen levels. The varying sensitivity and specificity of these CCTs have led trauma coagulation researchers and clinicians to use Viscoelastic Tests (VET) such as Thromboelastography (TEG) to provide Targeted Thromboelastographic Hemostatic and Adjunctive Therapy (TTHAT) in a goal directed fashion to those trauma patients in need of hemostatic resuscitation. This review describes the utility of VETs, in particular, TEG, to provide TTHAT in trauma and acquired non-trauma-induced coagulopathy.

Thromboelastography in Dogs with Chronic Hepatopathies

BACKGROUND

The coagulation status of dogs with liver disease is difficult to predict using conventional coagulation testing.

HYPOTHESIS/OBJECTIVES

To evaluate thromboelastography (TEG) results and associations with conventional coagulation results and indicators of disease severity and prognosis in dogs with chronic hepatopathies (CH).

ANIMALS

Twenty-one client-owned dogs.

METHODS

Dogs with CH were prospectively (10 dogs) and retrospectively (11 dogs) enrolled from 2008 to 2014. Kaolin-activated TEG was performed and compared with reference intervals by t-tests or Mann-Whitney tests. Correlation coefficients for TEG results and conventional coagulation and clinicopathologic results were determined. Significance was set at P < .05.

RESULTS

Dogs with CH had significant increases in R (5.30 min vs 4.33 min), K (3.77 min vs 2.11 min), and LY30 (4.77% vs 0.68%) and decreased angles (55.3° vs 62.4°). G value defined 9 of 21, 7 of 21, and 5 of 21 dogs as normocoagulable, hypercoagulable, and hypocoagulable, respectively. G and MA were correlated with fibrinogen (r = 0.68, 0.83), prothrombin time (PT; r = -0.51, -0.53), and activated partial thromboplastin time (aPTT; r = -0.50, -0.50). K was correlated with PT (r = 0.75) and protein C activity (r = -0.92). Angle was correlated with aPTT (r = -0.63). Clinical score was correlated with PT (r = 0.60), MA (r = -0.53), and R (r = -0.47). Dogs with hyperfibrinolysis (LY30 > 3.04%; 5 of 21) had significantly higher serum transaminase activities. Dogs with portal hypertension had significantly lower G, MA, and angle and prolonged, K, R, and PT.

CONCLUSIONS AND CLINICAL RELEVANCE

Dogs with CH have variable TEG results. Negative prognostic indicators in CH correlate with hypocoagulable parameters on TEG. Hyperfibrinolysis in dogs with CH is associated with high disease activity.

Correlation between thromboelastography and traditional coagulation test parameters in hospitalized dogs

A hospital-based, prospective cross-sectional study was used to compare kaolin-activated thromboelastography (TEG) parameters with traditional coagulation tests in 29 hospitalized dogs. Cases were included if the attending clinician requested coagulation testing. Blood was obtained from each dog and coagulation (prothrombin time, partial thromboplastin time, antithrombin activity, d-dimer concentration, and fibrinogen concentration) and TEG analyses were performed. Hematocrit (Hct) was also measured. Traditional coagulation results were evaluated for correlation with those from kaolin-activated TEG. Spearman’s correlation was used to calculate correlation coefficients. Fibrinogen was positively correlated with maximum amplitude (Pearson r=0.72, P<0.001) and global clot strength (Pearson r=0.72, P<0.001). There was no correlation between any of the remaining coagulation variables, TEG parameters, or Hct. Results of kaolin-activated TEG and traditional coagulation tests are not interchangeable means of monitoring coagulation derangements in this intensive care unit patient population. Determination of a true outcome measure is necessary to establish TEG’s clinical relevance to veterinary medicine.

Hemorrhagic, Hemostatic, and Thromboelastometric Disorders in 35 Dogs with a Clinical Diagnosis of Leptospirosis: A Prospective Study

Background

Leptospirosis in dogs is occasionally associated with a hemorrhagic syndrome, the pathophysiology of which is not fully understood.

Hypothesis/Objectives

To characterize hematologic, hemostatic, and thromboelastometric abnormalities in dogs with leptospirosis and to study their association with hemorrhagic diatheses and outcomes.

Animals

Thirty‐five client‐owned dogs.

Methods

A prospective observational single cohort study was conducted. Results from the CBC, coagulation tests (prothrombin, activated partial thromboplastin and thrombin times, fibrinogen, fibrin(ogen) degradation products, and D‐dimer concentrations), rotational thromboelastometry (TEM), signalment, hemorrhagic diatheses, occurrence of disseminated intravascular coagulation (DIC) at admission, and survival to discharge were recorded.

Results

The most common hematologic and hemostatic abnormalities were anemia (30/35), thrombocytopenia (21/35), and hyperfibrinogenemia (15/35). Eight dogs were diagnosed with DIC. A normal TEM profile was found in 14 dogs, a hypercoagulable profile in 14 dogs, and a hypocoagulable profile in 7 dogs. The 8 dogs with hemorrhagic diatheses at admission had significantly decreased platelet counts (P = .037) and increased D‐dimer concentrations (P = .015) compared with other dogs. Dogs with a hypocoagulable profile exhibited more hemorrhagic diatheses compared with the dogs that had normal and hypercoagulable profiles (P = .049). The mortality rate was lower in dogs with a hypercoagulable profile than in those with a hypocoagulable profile (21% vs 57%; P = .043). Disseminated intravascular coagulation was not a significant prognostic factor.

Conclusions and Clinical Importance

Thromboelastometric parameters were altered in dogs with both hypercoagulable and hypocoagulable profiles. A hypocoagulable profile was significantly correlated with hemorrhagic diathesis and higher mortality rate.

Laboratory tests for diagnosing and monitoring canine leishmaniasis

Although several reviews on canine leishmaniasis have been published, none thoroughly described clinicopathologic abnormalities and their clinical usefulness. The aim of this review was to provide information concerning current diagnostic tests relevant for clinical pathologists and from a practical perspective. Specifically, in canine leishmaniasis, nonregenerative normocytic normochromic anemia, thrombocytopenia, or leukogram changes may be present. Clinical chemistry and urinalysis may indicate renal dysfunction (azotemia, decreased urine specific gravity, proteinuria) and an inflammatory/immune response (increased acute phase proteins [APP] or α₂ - and/or γ-globulins). Although a potential gammopathy is usually polyclonal, it may also appear oligo- or monoclonal, especially in dogs coinfected by other vector-borne pathogens. When lesions are accessible to fine-needle aspiration (lymphoadenomegaly, nodular lesions, joint swelling), cytology is strongly advised, as the presence of Leishmania amastigotes in a pattern of pyogranulomatous inflammation or lymphoplasmacytic hyperplasia is diagnostic. If the cytologic pattern is inconclusive, the parasite should be identified by histology/immunohistochemistry or PCR on surgical biopsies. Alternatively, cytology and PCR may be performed on bone marrow samples where amastigotes, along with erythroid hypoplasia, myeloid hyperplasia, plasmacytosis, or secondary dysmyelopoiesis can be observed. Dogs with overt leishmaniasis generally have high antibody titers, while low titers predominate in immunologically resistant infected dogs or in exposed dogs with no parasite confirmation. Quantitative serology is recommended in clinically suspect dogs as high-titer antibodies titers may confirm the clinical diagnosis. In confirmed and treated dogs, renal function and inflammatory/immune response variables should be periodically monitored.

Thromboelastographic monitoring of the effect of unfractionated heparin in healthy dogs

OBJECTIVE

To characterize the correlation between thromboelastography (TEG) variables using strong activators and anti-Xa (AXa) activity in healthy dogs administered subcutaneous unfractionated heparin (UFH).

DESIGN

Prospective experimental study.

SETTING

University research facility.

ANIMALS

Eight adult random-source male dogs.

INTERVENTION

Dogs were randomized to receive subcutaneous UFH at 200, 250, or 300 IU/kg every 8 hours for a total of 10 injections. Blood samples were collected at time 0 (preheparin) and 3, 6, and 8 hours after the 1st (Day 1) and 10th (Day 4) UFH injection.  After the 8-hour blood sample was obtained on day 4, a 100 IU/kg IV bolus of UFH was administered and an additional blood sample was collected 1 hour later (hour 9). AXa activity, activated partial thromboplastin time (aPTT), and TEG (with up to 5 activators) were performed at each time point.  Modes of activation for TEG included  recalcified (Ca), Ca with heparinase (CaH), CaH and tissue factor 1:3600 (CTF3600H), Ca with tissue factor 1:100 (CTF100), and RapidTEG. Spearman rank correlations were calculated for each of the aforementioned parameters and the AXa activity. P-values were corrected for multiple comparisons with a Bonferroni correction.

MEASUREMENTS AND MAIN RESULTS

Significant correlations were found between AXa activity and the TEG R values generated with CTF100 (R = 0.83, P ≤ 0.0001) and RapidTEG (R = 0.90, P < 0.0001), as well as both forms of aPTT measurement (R = 0.86 and 0.84, P < 0.0001).

CONCLUSIONS

This study demonstrates that TEG variables derived using robust activation correlate with AXa activity as well as aPTT and have the potential to be used for monitoring UFH therapy in healthy dogs.  Future studies are warranted to evaluate its diagnostic utility in critically ill animals.

Retrospective comparison of thromboelastography results to postmortem evidence of thrombosis in critically ill dogs: 39 cases (2005-2010)

OBJECTIVE

To determine whether there is an association between thromboelastography (TEG) data and necropsy evidence of thrombosis in a cohort of critically ill dogs.

DESIGN

Retrospective study (2005-2010).

SETTING

University teaching hospital.

ANIMALS

Thirty-nine client-owned critically ill dogs for which TEG was performed within 7 days of complete necropsy.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Thrombi were found in 26 (67%) dogs. Spayed females (n = 20) were significantly more likely to have thrombosis (P = 0.0127). No significant association was found between presence of thrombosis and any TEG parameter, the calculated coagulation index, results of coagulation testing, type of vascular access, or clinical diagnosis. D-dimers were significantly higher in dogs with thrombosis (P = 0.0207) and a weak positive correlation was found between D-dimer value and number of sites of thrombosis (ρ = 0.18, P = 0.0045). Dogs with WBC > 16 × 10(3) /μL were more likely to have thrombosis compared to others (odds ratio 5.56, 95% confidence interval 1.2-25.7, P = 0.025).

CONCLUSIONS

This study found no association between any TEG parameter and the presence of thrombosis on postmortem examination.

Micro-elastometry on whole blood clots using actuated surface-attached posts (ASAPs)

We present a novel technology for microfluidic elastometry and demonstrate its ability to measure stiffness of blood clots as they form. A disposable micro-capillary strip draws small volumes (20 μL) of whole blood into a chamber containing a surface-mounted micropost array. The posts are magnetically actuated, thereby applying a shear stress to the blood clot. The posts' response to magnetic field changes as the blood clot forms; this response is measured by optical transmission. We show that a quasi-static model correctly predicts the torque applied to the microposts. We experimentally validate the ability of the system to measure clot stiffness by correlating our system with a commercial thromboelastograph. We conclude that actuated surface-attached post (ASAP) technology addresses a clinical need for point-of-care and small-volume elastic haemostatic assays.

Relationship Between Hematocrit Level and Cardiovascular Risk Factors in a Community-Based Population

BACKGROUND

This study aimed to determine the relationship between hematocrit (HCT) levels and cardiovascular risk factors in a community-based population of middle-aged adults.

METHODS

From April 2011 to February 2012, a total of 1,884 middle-aged adults were selected from a community-based population in China. Blood and urine samples were collected for routine blood and urine tests, and measurement of plasma glucose and lipid levels. Baseline information including traditional cardiovascular risk factors was obtained by standard questionnaire to analyze. We evaluated the distribution of the HCT values for middle-aged adults with or without cardiovascular risk factors. There were 548 males and 1,336 females in this study. The mean age of all subjects was 54.7 ± 6.7 years. There were 1,209 subjects with risk factors and 675 without risk factors.

RESULTS

The HCT levels in subjects with risk factors were higher than those without risk factors (P = 0.005). According to a simplified tool for evaluation of the 10-year risk of ischemic cardiovascular diseases (CVDs) in Chinese populations, all subjects were divided into four groups: the ultralow-risk group (1,367, 72.6%), low-risk group (232, 12.3%), intermediate-risk group (201, 10.7%), and high-risk/ultrahigh-risk group (84, 4.4%). Compared with HCT levels in the ultralow-risk group, significant differences were found in the low-risk, intermediate-risk, and high-risk/ultrahigh-risk groups (all P < 0.05).

CONCLUSION

Our results indicate that elevated HCT levels may be positively associated with cardiovascular risk factors. Thus, the combination of HCT values and cardiovascular risk factors may enable early diagnosis of CVDs.