Partnership on Rotational ViscoElastic Test Standardization (PROVETS): Evidence-based guidelines on rotational viscoelastic assays in veterinary medicine

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.

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.

Thromboelastometry for assessment of hemostasis and disease severity in 42 dogs with naturally-occurring heatstroke

BACKGROUND

Thromboelastometry (TEM) provides a comprehensive overview of the entire coagulation process and has not been evaluated in heatstroke-induced coagulopathies in dogs.

OBJECTIVES

To determine the diagnostic and prognostic utility of TEM in dogs with heatstroke.

ANIMALS

Forty-two client-owned dogs with heatstroke.

METHODS

Prospective observational study. Blood samples for intrinsic and extrinsic TEM (INTEM and EXTEM, respectively) were collected at presentation and every 12 to 24 hours for 48 hours. Coagulation phenotype (hypo-, normo-, or hypercoagulable) was defined based on TEM area under the 1st derivative curve (AUC).

RESULTS

Case fatality rate was 31%. Median TEM variables associated with death (P < .05 for all) included longer INTEM clotting time, lower AUC at presentation and at 12 to 24 hours postpresentation (PP), lower INTEM alpha angle, maximum clot firmness, and maximum lysis (ML) at 12 to 24 hours PP, and lower EXTEM ML at 12 to 24 hours PP. Most dogs were normo-coagulable on presentation (66% and 63% on EXTEM and INTEM, respectively), but hypo-coagulable 12 to 24 PP (63% for both EXTEM and INTEM). A hypo-coagulable INTEM phenotype was more frequent at presentation and 12 to 24 PP among nonsurvivors compared to survivors (55% vs 15% and 100% vs 50%, P = .045 and .026, respectively). AKI was more frequent (P = .015) in dogs with hypo-coagulable INTEM tracings at 12 to 24 hours. Disseminated intravascular coagulation was more frequent (P < .05) in dogs with a hypo-coagulable INTEM phenotype and in nonsurvivors at all timepoints.

CONCLUSIONS AND CLINICAL RELEVANCE

Hypocoagulability, based on INTEM AUC, is predictive of worse prognosis and occurrence of secondary complications.

Point-of-care viscoelastic coagulation monitor parameters in Amazon parrots (Amazona spp.)

OBJECTIVE

To evaluate the feasibility of the point-of-care viscoelastic coagulation monitor (VCM) in Amazon parrots (Amazona spp.) and describe the parameters with fresh whole-blood samples in healthy Amazon parrots.

DESIGN

A total of 18 Amazon parrots were enrolled. Physical examinations, a CBC, and a biochemistry profile, including bile acids, were performed on all parrots. VCM tracings were obtained at the time of venipuncture for baseline laboratory work.

MEASUREMENTS AND MAIN RESULTS

The median clot time was 2102 seconds (range: 38.6-3599 s), median clot formation time was 929 seconds (range: 21.4-1711 s), median alpha angle was 20 (range: 6-67), and the median maximum clot formation was 8.5 (range: 0-36). The median lysis index at 30 minutes (LI30) was 100 (range: 98-100), and the median lysis index at 45 minutes (LI45) was 100 (range: 90-100). Of 18 samples, alpha angles were not reported in 7 samples, LI30 was not reported in 10 samples, and LI45 was not reported in 12 samples. Of the qualitative curves, 6 reflected normal mammalian curves, and the remainder were consistent with a hypocoaguable state.

CONCLUSIONS

The results were markedly variable, with the majority of VCM tracings being hypocoagulable in comparison with reference intervals established for dogs and cats. Using these protocols, the VCM is not reliable in Amazon parrots. Future areas of investigation include altering the temperature during sample analysis, the use of activators, or an exchange of clotting reagents for an extrinsic pathway activator, which may contribute to the success of this device in avian species.

Prospective evaluation of platelet function and fibrinolysis in 20 dogs with trauma

OBJECTIVES

To determine platelet function and assess fibrinolysis in dogs following trauma using multiple electrical impedance aggregometry and a modified thromboelastographic (TEG) technique. To determine if the severity of trauma, as assessed by the Animal Trauma Triage (ATT) score and clinicopathological markers of shock, is associated with a greater degree of platelet dysfunction and fibrinolysis.

SETTING

University teaching hospital.

ANIMALS

Twenty client-owned dogs with trauma (occurring <24 h prior to admission and blood sampling) and ATT score of >4 were prospectively recruited. A control group of 10 healthy dogs was included.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Platelet function was measured using multiple electrode platelet aggregometry (MEPA) utilizing arachidonic acid, ADP, and collagen agonists. Fibrinolysis was assessed in citrated whole blood with the addition of tissue plasminogen activator (tPA; 50 U/mL) using kaolin-activated TEG. Conventional statistical analysis was performed to compare coagulation parameters between the groups and assess linear correlations. Median (interquartile range) ATT score was 5 (5-7), and 65% (n = 13) of dogs suffered polytrauma. Mean (± SD) time from trauma to blood sampling was 9 hours (± 6). Median (interquartile range) shock index and plasma lactate concentration were 1.1 (0.7-2.0, n = 16) and 2.9 mmol/L (0.9-16.0, n = 18), respectively. Four dogs did not survive to discharge (20%). There were no differences between the trauma and control group coagulation variables. A moderate negative correlation between ATT score and area under the curve for ADP was found (P = 0.043, r2  = -0.496).

CONCLUSIONS

Preliminary evaluation of platelet function measured by MEPA, and fibrinolysis measured by tPA-modified TEG, is not significantly different in this population of dogs with traumatic injury compared to healthy dogs.

Thromboelastographic results and hypercoagulability in dogs with surgically treated hepatocellular adenoma and carcinoma: A Veterinary Society of Surgical Oncology prospective study

BACKGROUND

The most common haemostatic abnormality in dogs with cancer is hypercoagulability. A transient hypercoagulability has been documented in people with hepatocellular carcinoma (HCC) that resolves within weeks following hepatic tumour resection.

OBJECTIVE

The objective was to compare the haemostatic status of dogs with liver tumours and healthy control dogs, by comparing coagulation and thromboelastography (TEG) measurements at three time points.

METHODS

Liver tumour and healthy control dogs receiving surgery for liver lobectomy and ovariohysterectomy, respectively, were prospectively enrolled. All dogs had blood collected at three time points: pre-operative, 24 h post-operative and ~2 weeks post-operative. Haematological and haemostatic values were compared across time points in each group using repeated measures ANOVA tests.

RESULTS

Ten and eight dogs were enrolled for the liver and control groups, respectively. Platelet count was significantly higher in the liver group than the control group at all time points, but within the normal range (pre-operative: 438.7 vs. 300.9 × 109 /L, p = .0078; 24 h post-operative: 416.2 vs. 283.9 × 109 /L, p = .0123; 10-14 days post-operative: 524.6 vs. 317.3 × 109 /L, p = .0072). The measure of the overall coagulant state (G-value) was significantly increased for the liver group compared to the control group at all time points (pre-operative: 15.6 vs. 8.6 d/sc, p = .0003; 24 h post-operative: 18.3 vs. 11.2 d/sc, p = .039; 10-14 days post-operative: 15.1 vs. 9.6 d/sc, p = .015).

CONCLUSION

The liver group was hypercoagulable based on elevated G-values at all time points compared to the control group. This hypercoagulability was attributed to the effect of hepatic tumours alone, and not secondary to surgery and anaesthesia.

Preliminary evaluation of reference intervals for a point-of-care viscoelastic coagulation monitor (VCM Vet) in healthy adult horses

OBJECTIVE

To evaluate a point-of-care viscoelastic coagulation monitor (VCM Vet) for use in horses by assessing variability between devices and establish reference intervals (RIs) for healthy adult horses.

DESIGN

Prospective observational study.

SETTING

Two university teaching hospitals.

ANIMALS

Healthy adult horses (n = 68).

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Blood collected by direct jugular venipuncture was applied directly from the syringe into 2 VCM Vet cassettes to establish coefficients of variation (CVs) and RIs for reported parameters of clotting time (CT), clot formation time (CFT), alpha angle, amplitude at 10 and 20 minutes, maximum clot firmness, and lysis index at 30 and 45 minutes. CVs for each parameter were within clinical tolerance. There was a significant difference in CT between institutions (P < 0.001). Differences in CV were found between institutions for CT (P = 0.003) and CFT (P = 0.01). Healthy horse RIs were calculated for the overall data set and each individual institution. Calculated RIs were as follows: CT, 255.6-1233.9 seconds; CFT, 89.4-581 seconds; alpha angle, 11.4-53.6°; maximum clot firmness, 18-37.7; lysis index at 30 minutes, 97.3%-102.1%; lysis index at 45 minutes, 80.8%-103.3%; amplitude at 10 minutes, 8.7-28.3; and amplitude at 20 minutes, 17.4-35.7.

CONCLUSIONS

VCM Vet is a repeatable and practical option for rapid point-of-care assessment of hemostasis in horses but has a wide RI and is susceptible to variability. Establishment of institution-specific RIs is recommended.

Evaluation of thrombin generation in dogs administered clopidogrel

Introduction

The antiplatelet effect of clopidogrel can vary between patients. A modified thromboelastography (TEG) protocol (TEG-Platelet Mapping assay® [TEG-PM]) can be used for clopidogrel monitoring but is not widely available. Thrombin generation (TG) assays could offer a novel alternative. The main objective of this pilot study was to assess TG assay variables (lag time, peak, endogenous thrombin potential [ETP]) in dogs before and after 7 days of clopidogrel administration and compare with TEG-PM variables (maximum amplitude [MA]-ADP and percentage (%) inhibition).

Methods

Six healthy mix-breed dogs were enrolled in this pilot study. Blood samples for platelet count, TG assays, and TEG-PM were obtained at two time points, corresponding to baseline, and after 7 days of clopidogrel administration (mean 2.3 +/- 0.3 mg/kg PO q24 hours). Data were then compared with a Student's t-test.

Results

There was no significant change in TG assay variables performed on platelet poor plasma after 7 days of clopidogrel administration: lag time (Day 1: 1.8 +/- 0.2 min, Day 7: 1.8 +/- 0.2 min, p = 0.42); peak (Day 1: 76 +/- 7 nM, Day 7: 72 +/- 10 nM, p = 0.49); and ETP (Day 1: 399 +/- 27 nM*min, Day 7: 392 +/- 32 nM*min; p = 0.49). There were significant changes in TEG MA-ADP (Day 1: 19 +/- 8 mm, Day 7: 9 +/- 6 mm, p = 0.04) and % inhibition (Day 1: 58 +/- 27, Day 7: 99 +/- 0.3, p = 0.02).

Discussion

Clopidogrel administration did not lead to changes in TG assay variables performed on platelet poor plasma samples, despite concomitant changes in TEG-PM variables consistent with platelet inhibition. Based on this pilot study, thrombin generation performed on platelet poor plasma may not be a useful antiplatelet monitoring tool in dogs.

Hemostatic and thromboelastographic parameters in dogs with renal azotemia

Background and Aim

Humans and dogs with azotemia can develop coagulation disorders. Therefore, this study aimed to evaluate the coagulation profiles and thromboelastographic parameters in dogs with acute kidney injury (AKI) and chronic kidney disease (CKD).

Materials and Methods

In this prospective study, 31 client-owned dogs with renal azotemia (creatinine >220 μmol/L) were enrolled. Clinical signs of hemostatic disorders, complete blood count, coagulation profile, D-dimers, thromboelastography, and 28-day survival data were obtained and analyzed using the t-test, Mann-Whitney U test, and Chi-square test. Statistical significance was set at p < 0.05.

Results

Seventeen dogs with AKI, 10 with CKD, and four with acute-on-chronic kidney injury (AoC) were enrolled. Ten dogs (AKI, 8/17; CKD, 2/10) had thrombocytopenia. Prothrombin time was prolonged in four dogs with AKI and longer in dogs with AKI than in dogs with CKD (p = 0.004). The activated partial thromboplastin time was prolonged in 23 dogs (AKI, 14/17; CKD, 7/10; AoC, 3/4) and was longer in azotemic dogs than in healthy control dogs (p = 0.003). Thromboelastographic tracings were hypocoagulable in three dogs with AKI and hypercoagulable in 16 dogs (AKI 4/17, CKD 9/10, AoC 3/4). The thromboelastographic values for maximum amplitude (p < 0.001) and global clot strength (p < 0.001) were lower in dogs with AKI than in those with CKD.

Conclusion

Hypercoagulable thromboelastographic tracings were observed in dogs with CKD, whereas coagulation times were prolonged in dogs with AKI. However these findings should be validated by further studies.

Comparison of a viscoelastic point-of-care coagulation monitor with thromboelastography in sick dogs with hemostatic abnormalities

BACKGROUND

Viscoelastic coagulation monitor (VCM-Vet) is a point-of-care device that has been used to characterize hemostatic abnormalities in sick pets but has not been validated in veterinary patients.

OBJECTIVES

We aimed to compare VCM-Vet and thromboelastography (TEG) in sick dogs with suspected disorders of hemostasis.

METHODS

Duplicate VCM-Vet tests using untreated native blood performed concurrently on two VCM-Vet machines, and simultaneous TEG tests were performed (one citrated native (CN), and one activated with tissue factor (TF) at a 1:3600 dilution). Each VCM-Vet result was compared with both TF-activated and CN TEG.

RESULTS

Fifty-three dogs were enrolled. Eleven cases displayed apparent hyperfibrinolysis. Spearman correlation coefficients for individual VCM-Vet devices and CN and TF TEG were obtained between R and CT values and ranged from 0.21 to 0.27, CFT and K (r = 0.60-0.67), angles (r = 0.51-0.62), and MCF and MA (r = 0.85-0.87). Comparison of the two VCM-Vet devices displayed positive correlations for all clot formation parameters with Lin's concordance correlation coefficients of 0.75-0.95. Variable lysis parameter agreement existed between the VCM-Vet devices and VCM-Vet and TEG. When samples were classified as hypercoagulable or coagulopathic, VCM-Vet had a low positive predictive value (17-33%) for the detection of hypercoagulable states and a moderate negative predictive value (64-74%) for the detection of coagulopathy as defined by TEG.

CONCLUSIONS

VCM-Vet and TEG had variable correlations in clot formation values and a strong correlation for final clot strength. More information is needed to make conclusions about the lysis parameters. Artifact in the fibrinolysis portion of the test can confound the interpretation of VCM-Vet results.

Evaluation of a Viscoelastic Coagulation Monitoring System (VCM Vet®) and Its Correlation with Thromboelastometry (ROTEM®) in Diseased and Healthy Dogs

Thromboelastometry provides a real-time assessment of global coagulation in whole blood. A novel bed-side viscoelastic coagulation monitor (VCM) has been developed for use in small animals. The aims of the study were to determine inter-device agreement of two VCM devices, to evaluate the correlation between VCM and rotational thromboelastometry as a reference method (ROTEM), and to determine the sensitivity and specificity of VCM to diagnose hypo-, normo-, and hypercoagulability. ROTEM (extrinsic and intrinsic activation) analysis was performed using citrated blood and VCM analysis using native blood. Twenty healthy and forty diseased dogs with and without coagulopathies were enrolled. The VCM inter-device agreement was moderate to strong for most of the parameters, depending on the grading scale. Correlation between VCM and ROTEM was moderate to strong for parameters of clotting time and clot strength. The VCM most likely detects true hypocoagulability and reliably rules out hypocoagulability. The VCM has a high sensitivity in diagnosing normocoagulability, but incorrectly classified dogs with abnormal coagulation as normocoagulable. The VCM was not able to detect hypercoagulability. ROTEM and VCM cannot be used interchangeably.

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.

The hemostatic profile of cold-stored whole blood from non-greyhound and greyhound dogs over 42 days

Objectives

To compare the hemostatic characteristics of cold-stored whole blood (CSWB) from non-greyhound dogs (NGD) and greyhound dogs (GD) over 42 days of storage, notably, platelet closure time (PCT) (NGD only), manual platelet count (PLT) (GD only), ellagic acid (INTEM) and tissue factor activated (EXTEM) rotational thromboelastometry, prothrombin (PT) and activated partial thromboplastin time (aPTT), fibrinogen concentration (FIB), and the activities of factors (F) FII, FV, FVII, FVIII, FIX, FX, FXIII antigen (FXIII:Ag), and von Willebrand factor antigen (vWF:Ag).

Design

Whole blood from 10 NGD and 10 GD, was refrigerated in CPD blood bags at 4°C for 42 days. Blood was analyzed before refrigeration (day 0) and at day 1 (d1), 3, 5, 7, 10, 14, 17, 21, 24, 28, 31, 35, 38, and 42. Multivariate linear mixed effects models were created to evaluate coagulation parameters over time and compare NGD and GD. Data are summarized as estimated marginal means with 95% confidence intervals. Significance was set at P < 0.05.

Results

The PCT for all NGD CSWB was above the device limit by d7. The PLT for GD CSWB did not change during storage. The mean alpha-angle for INTEM and EXTEM decreased to <50% of baseline at d38 and d31 for NGD, and d31 and d17 for GD CSWB. The mean maximum clot firmness (MCF) for INTEM and EXTEM reduced to <50% of baseline at d42 and d28 for both GD and NGD. PT and aPTT for NGD and GD increased over time. For NGD CSWB, the mean FVIII and vWF:Ag activities decreased to <50% of baseline at d7 and d28, respectively, and FIB reached 0.982 g/dL by d24. For GD CSWB, FVIII, FXIII:Ag and FV activities decreased to <50% of baseline by d3, d38, and d38, respectively, and FIB was 0.982 g/dL at baseline. Alpha-angle and MCF for both INTEM and EXTEM, and activities for FII, FV, FIX, FXIII:Ag were significantly lower, and vWF:Ag was significantly higher overall in GD CSWB compared with NGD. A significant difference in the pattern of change over time was detected between NGD and GD in EXTEM alpha-angle, INTEM and EXTEM MCF, FII, and FVIII activities.

Conclusions

The in vitro viscoelastic parameters of GD and NGD CSWB declines over 42 days, but numerous hemostatic parameters (INTEM and EXTEM alpha-angle and MCF, activity of FII, FV, FV, FVII, FIX, FX, FXIII:Ag, vWF:Ag, and FIB) remain within 50% of baseline for more than 14 days. CSWB from GD compared to NGD has reduced hemostatic activity overall, but a similar pattern of decline for most parameters over time.

Evaluation of Haemostasis in Dogs Affected by Resectable Malignancy

Dogs with neoplasm are at risk of thrombosis, yet there is no information on the haemostatic alterations that may result from the surgeries performed to remove neoplastic masses. The aim of this study was to observe the characteristics of haemostasis in dogs undergoing surgery to remove a malignancy by means of rotational thromboelastometry and thrombin generation. Haemostasis was assessed immediately before surgery (T0), 24 h after surgery (T1), and two weeks after surgery (T2). Statistically significant differences were found between the thromboelastometric parameters at T0 vs. T1, with increases observed in MCF, the α angle, and G parameters in the ex-TEM and in-TEM profiles. In the thromboelastometric analysis performed after surgery differences were identified between T1 and T2, with a decrease observed in parameters such as CFT, MCF, the α angle, and G. Between T0 and T2, only a significant decrease in CT was detected in the fib-TEM profile. No differences were found in the comparison among the results obtained via thrombin generation. In dogs with resectable malignancies, the surgeries performed to remove cancer affected coagulation, causing a tendency towards hypercoagulability. The interference with coagulation was transient, and 2 weeks after surgery, the thromboelatometric results returned to those obtained before surgery (T0).

Point-of-care viscoelastic coagulation assessment in healthy dogs during the perianesthetic period

Background

The viscoelastic coagulation monitor (VCM Vet) is a novel, portable device that provides a global assessment of hemostasis. The study aims were to evaluate serial viscoelastic analysis during the perianesthetic period in healthy dogs and to compare the agreement between two VCM Vet devices. Twenty healthy dogs undergoing orthopedic surgery were enrolled. Whole blood samples were collected from an intravenous catheter at four time points: baseline, 15 min after premedication, 60 min after inhalant initiation, and 60 min after inhalant termination. Viscoelastic tests were performed in duplicate on different devices, providing: clot time (CT; seconds), clot formation time (CFT; seconds), alpha angle (α; degrees), amplitude (units) at 10 (A10) and 20 (A20) minutes post clot time, maximum clot firmness (MCF; units), and lysis index (%) at 30 (Li30) and 45 (Li45) minutes post maximum clot formation.

Results

One hundred sixty samples were analyzed. The speed of CT and CFT significantly decreased an average of 25.5 s (95% confidence interval [CI]15.9–35.0) and 6.9 s (95% CI 3.1–10.7) per time point, respectively. There were no significant changes in clot strength or lysis variables. The Bland–Altman style plot shows an acceptable rate of agreement for all variables with intra-class correlation ranging from 0.64–0.94.

Conclusion

The rate of clot formation (CT and CFT) decreased over the perianesthetic period in healthy dogs undergoing surgery. These changes were small and occurred without changes in clot strength or fibrinolysis rate, thus were not clinically relevant. There was clinically acceptable consistency between devices.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12917-022-03442-x.

Comparison of assessment of coagulation in healthy dogs by the TEG 6s and TEG 5000 viscoelastic analyzers

The TEG 6s (Haemonetics) point-of-care viscoelastic analyzer is portable, compact, simple to use, and has the potential for rapid viscoelastic analysis that can guide the treatment of veterinary patients at the site of care. Although approved for use in people, the TEG 6s has yet to be evaluated for hemostatic analysis in veterinary medicine. Citrated whole blood (CWB) was collected from 27 healthy dogs. An aliquot of CWB from each dog was diluted by 33% with an isotonic crystalloid, representing an in vitro model of hemodilution. Unaltered and diluted CWB samples were analyzed using 2 TEG 6s and 6 TEG 5000 (Haemonetics) analyzers. The 6 TEG 5000 analyzers ran duplicate analyses of either unaltered or diluted samples using 1 of 3 reagents (Haemonetics): Kaolin TEG, RapidTEG, or TEG Functional Fibrinogen. Duplicate TEG 5000 analyses were averaged and compared with a single TEG 6s analysis. Lin concordance correlation coefficient and Bland-Altman plots were used to evaluate agreement of reaction time, kinetic time, alpha angle, maximum amplitude (MA), and G value (G) for samples activated with Kaolin TEG, and agreement of MA for samples activated with RapidTEG between the 2 machines. Overall, agreement between the TEG 6s and TEG 5000 analyzers was poor. Viscoelastic measurements by the TEG 6s and TEG 5000 in healthy dogs were not all interchangeable. Agreement was satisfactory only for MA and G measurements of diluted blood samples activated with Kaolin TEG, and MA measurements for both unaltered and diluted blood samples activated with RapidTEG.

Comparison of Jugular vs. Saphenous Blood Samples, Intrarater and In-Between Device Reliability of Clinically Used ROTEM S Parameters in Dogs

Rotational Thromboelastometry (ROTEM) allows for the global assessment of hemostasis in whole blood samples. Preanalytical and analytical factors may influence test results, and data about the reliability and reproducibility of lyophilized ROTEM tests are scarce. Therefore, the objective of this study was to evaluate the influence of blood collection site on ROTEM S parameters and to assess intrarater and in-between device variability. A total of thirty, healthy, staff-owned dogs were included. Blood collection and ROTEM analysis were performed by trained staff according to a standardized protocol. Extrinsically activated (tissue factor; Ex-TEM S), with the addition of cytochalasin for platelet inhibition (Fib-TEM S), and intrinsically activated (In-TEM) analyses were performed. Analysis of our data showed significant variability for various Ex-TEM S and Fib-TEM S parameters from different collection sites and intrarater and in-between device measurements. We conclude that serial monitoring with ROTEM should be performed on the same device, with blood always taken from the same collection site using a standardized blood sampling technique. While In-TEM S, apart from maximum lysis, showed very stable and reliable results, we suggest interpreting especially clotting and clot formation parameters from Ex-TEM S and Fib-TEM S tests with caution and using duplicate measurements to detect outliers and to prevent initiation of incorrect therapies.

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.

Circulating hyaluronan as a marker of endothelial glycocalyx damage in dogs with myxomatous mitral valve disease and dogs in a hypercoagulable state

The endothelial glycocalyx (eGlx) lines the luminal surface of endothelial cells, maintaining vascular health. Glycocalyx damage is pathophysiologically important in many diseases across species however few studies have investigated its breakdown in naturally occurring disease in dogs. The aims of the study were to investigate eGlx damage in dogs with myxomatous mitral valve disease (MMVD) diagnosed on echocardiography, and dogs in a hypercoagulable state diagnosed using thromboelastography (TEG), by measuring serum hyaluronan concentrations. Serum hyaluronan was quantified in dogs with MMVD (n = 27), hypercoagulability (n = 21), and in healthy controls dogs (n = 18). Serum hyaluronan concentrations were measured using a commercially-available ELISA validated for use in dogs. Hyaluronan concentrations were compared among groups using Kruskal-Wallis tests, and post-hoc with Dunn’s tests. Serum hyaluronan concentrations (median [range]) were significantly increased in dogs with MMVD (62.4 [22.8–201] ng/mL; P = 0.031) and hypercoagulability (92.40 [16.9–247.6] ng/mL; P < 0.001) compared to controls (45.7 [8.7–80.2] ng/mL). Measurement of serum hyaluronan concentration offers a clinically applicable marker of eGlx health and suggests the presence of eGlx damage in dogs with MMVD and dogs in a hypercoagulable state.

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Few studies have investigated endothelial glycocalyx breakdown in disease in dogs.

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Serum hyaluronan is a clinically applicable marker of endothelial glycocalyx health.

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Serum hyaluronan was significantly increased in dogs with mitral valve disease.

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Serum hyaluronan was significantly increased in dogs in a hypercoagulable state.

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Increased serum hyaluronan may indicate glycocalyx shedding in these diseases.

Use of Citrated Whole Blood for Point-of-Care Viscoelastic Coagulation Testing in Dogs

Background

A new, portable bedside coagulation monitor (VCM Vet) has provided a user-friendly, cartridge-based method to perform viscoelastic testing. However, the use of native whole blood limits the time to analyze the sample to minutes. The objective of this study is to assess whether citrated whole blood can be utilized with the cartridge-based system and whether the results are comparable to those of native whole blood. A secondary objective is to assess the viability of citrated whole blood results after up to 4 hours of resting.

Methods

The study population consisted of 10 healthy mixed breed dogs. Whole blood samples were collected via jugular venipuncture. Blood was immediately transferred to the VCM test cartridge for native whole blood control group analysis per the manufacturer's instructions, and the remainder was used to fill two 3.2% sodium citrate vacutainer tubes. Test group analysis was performed on samples from each tube concurrently after a rest period of 30 min (baseline), 2 h, and 4 h. Citrated whole blood samples were recalcified for analysis immediately prior to introduction into the test cartridge. Data was recorded for all reported parameters. Results from the citrate groups were compared to the control group and to the citrated baseline to assess for differences. Overall results were compared using mixed ANOVA models. Where found, specific differences were evaluated using Tukey's test. Within-sample variation was investigated and reported as median (range). A p < 0.05 was considered significant.

Results

Samples were obtained for a total of 10 control runs and 20 citrated whole blood runs. Comparison of controls to the citrated test groups revealed significant differences in CT (p < 0.001) and MCF (p < 0.002). There were no significant differences between test groups compared to citrated baselines for any parameter. Selected median coefficients of variation were 6.8% (0–68.8%) for CT, 2.4% (0–19.46%) for alpha angle, 3.2% (0–27.4%) for MCF, and 0% (0–16.3%) for 45-min LY45.

Conclusion

Citrated whole blood samples can be used with the VCM Vet device; however, new reference intervals for use with citrated whole blood will be required. Results using citrated whole blood samples are not significantly different from baseline after up to 4 h of resting.

Comparison of the effects of open-tube and evacuated tube-assisted sampling methods on thromboelastography variables for blood samples from healthy dogs

OBJECTIVE

To compare the effects of open-tube blood sampling with previously investigated blood sampling methods via evacuated tube on thromboelastography variables for blood samples from dogs.

ANIMALS

10 healthy Beagles from the research colony owned by the Clinic of Small Animal Internal Medicine, University Veterinary of Medicine, Vienna, were used.

PROCEDURES

In this prospective study, blood was sampled from each dog serially into citrate solution-containing tubes via 20-gauge needle. One evacuated tube was filled from a jugular vein via the evacuated tube port, and the second tube was opened and filled by catching blood flowing through the needle from a lateral saphenous vein. Venipuncture quality was scored with a previously described method. Thromboelastography was performed for each sample.

RESULTS

Inferential statistics used with the Wilcoxon signed rank test showed significant differences in reaction time (R) of 3.43 ± 0.84 minutes versus 4.53 ± 0.62 minutes (mean ± SD) between evacuated tube assisted and open-tube sampling, respectively. No other significant differences were identified.

CLINICAL RELEVANCE

The sampling methods compared have a small but significant effect on R in thromboelastographic analysis for blood samples from healthy dogs. Shear stress by vacuum sampling seems to accelerate coagulation in jugular blood samples harvested by evacuated tube, resulting in a shortened R. Results suggested that the open-tube method avoids shear stress induced activation of coagulation and is an appropriate sampling method for thromboelastography when used within a standardized protocol.

Assessment of hemostasis in dogs with gastric-dilation-volvulus, during resuscitation with hydroxyethyl starch (130/0.4) or hypertonic saline (7.5%)

OBJECTIVE

To compare the impact of an IV bolus of hydroxyethyl starch 130/0.4 (HES) or hypertonic saline 7.5% (HS) on hemostasis in dogs resuscitated for gastric-dilation-volvulus (GDV).

DESIGN

Open-label, parallel-group randomized clinical trial.

ANIMALS

Twenty-three client-owned dogs.

INTERVENTIONS

Dogs affected by GDV and shock were randomly assigned to receive HES at 10 mL/kg or HS at 4 mL/kg every 15 minutes. Blood samples were collected for blood gas analysis, PCV, total plasma protein, albumin, standard coagulation profile, and thromboelastometry (ROTEM) at baseline (T0) and at the end of bolus (T1). To assess the differences between the 2 groups at T1, Student's t-test or Wilcoxon rank-sum test was used. To evaluate the differences between T0 and T1, ANOVA for paired data or Wilcoxon matched-pairs signed-ranks test was used. P < 0.05 was considered significant.

MEASUREMENT AND MAIN RESULTS

Hemostasis was evaluated by means of prothrombin time, activated partial thromboplastin time, fibrinogen, and ROTEM. The study included 13 dogs in the HES group and 10 dogs in the HS group. Differences were found between groups at T1: increase in clotting time (P = 0.018) and decrease in fibrinogen level (P = 0.021) in the HS-treated group. Between T0 and T1, there were differences for the HES group: increase in clot formation time (P = 0.046), decrease in maximum clot firmness (P = 0.002) in ex-TEM profile, and decrease in maximum clot firmness (P = 0.0117) in fib-TEM profile. Between T0 and T1, the following differences were noted for the HS group: increase in clotting time (P = 0.048) and clot formation time (P = 0.0019), decrease in maximum clot firmness (P = 0.031) and α angle (P = 0.036) in ex-TEM profile, decrease in α angle (P = 0.036) in in-TEM profile, and decrease in maximum clot firmness (P = 0.017) in fib-TEM profile.

CONCLUSION

In dogs affected by GDV, HES or HS infusion caused a similar tendency toward hypocoagulability, with few differences between the 2 groups.

The effect of analytical temperature on thromboelastography tracings in dogs

Viscoelastic testing methods such as thromboelastography (TEG) are becoming increasingly available to veterinarians in a clinical setting. TEG is useful in determining therapeutic transfusion needs and assessing global abnormalities of hemostasis of patients, given that it provides a more comprehensive assessment of coagulation than traditional tests. TEG is standardly performed at 37°C, which is considered a normal body temperature for human patients; however, 37°C is lower than normal body temperature for most canine patients. In an in vitro study, we investigated the potential effect that this difference in body temperature and test temperature might have on TEG results. Citrated blood samples were collected from clinically normal, as well as sick, dogs with various body temperatures. Samples were analyzed concurrently at the patient's body temperature and at 37°C. There was very high correlation between TEG performed at body temperature and at 37°C for R (min) and MA (mm), high correlation for K (min) and alpha angle (deg), and moderate correlation for LY30 (%) and LY60 (%). For canine patients with normal to mildly abnormal body temperatures, performance of TEG at the standard 37°C is acceptable.

Completeness of reporting of systematic reviews in the animal health literature: A meta-research study

Systematic reviews are a valuable tool for evaluating the efficacy of interventions and for quantifying associations. To be properly assessed, reviews must be comprehensively reported. The primary objective of this study was to evaluate the completeness of reporting of systematic reviews and meta-analyses in animal health. The secondary objective was to further characterize methods for literature searches and risk of bias assessments and to document whether the risk of bias component represented an assessment of risk of bias, study quality, or levels of evidence based on the primary studies included. The dataset comprised 91 systematic reviews or meta-analyses of interventions or exposures with at least one health outcome measured at the animal or animal byproduct level, in any companion or food animal species and published between 2014 and 2018. Two reviewers independently collected information on whether each item in the PRISMA reporting guidelines was reported, with disagreements resolved by consensus. There was considerable variability in the completeness of reporting among reviews; some items, such as eligibility criteria for inclusion, were reported in most reviews (>65 %). Other items were not consistently reported; for instance, in 60 % (54) of the reviews there was no information provided on the sample size of individual studies, populations, interventions and comparators, outcomes, or follow up period. Although 89 % (81) of systematic reviews with meta-analysis included the effect size estimate and confidence intervals, it was not possible to determine which study designs were included for 30 % (14) of reviews. Results from individual PRISMA item questions were combined to determine whether all aspects of each recommended item were reported; 71 % of items were adequately reported in less than half the systematic reviews without a meta-analysis, 35 % of the items were adequately reported in less than half the systematic reviews with a meta-analysis, and 71 % of items were adequately reported in less than half of the meta-analyses without a systematic review component. An assessment of individual study level bias was included in 64 % of the reviews, although this component included an evaluation of risk of bias (35 reviews), study quality (25 reviews), or levels of evidence based on study design (12 reviews). Reporting guidelines or clinical guidelines were inappropriately used to assess risk of bias in 9 reviews. Overall, the results of this study reveal that reporting of systematic reviews in the animal health literature is suboptimal and improvements are needed to enhance utility of these reviews.

Pharmacokinetics and Biologic Activity of Apixaban in Healthy Dogs

Thrombosis is common in critically ill dogs and causes considerable morbidity and mortality. The direct factor Xa inhibitor apixaban is safe, efficacious, and convenient in humans. This study aimed to determine the pharmacokinetics (PK), bioactivity, protein binding, and bioavailability of apixaban following intravenous (IV) and oral (PO) administration to healthy dogs. Six healthy, adult, mixed-breed dogs were administered apixaban 0.18 mg/kg IV and then following a minimum 2-week washout period administered apixaban 0.2 mg/kg PO. Dogs were monitored using an apixaban-calibrated anti-Xa bioassay, prothrombin time (PT) and activated partial thromboplastin time (aPTT) and tissue-factor thromboelastography (TF-TEG). Plasma apixaban concentrations were measured using liquid chromatography-tandem mass spectrometry. Concentration-time plots were constructed, and PK modeling performed using compartmental methods. Administration of IV and PO apixaban was well-tolerated. Following IV administration, mean half-life was 4.1 h, and volume of distribution was 177 ml/kg. Apixaban was highly protein bound (98.6%). Apixaban concentrations and anti-Xa activity were highly correlated (R2 0.994, P < 0.0001). Intravenous apixaban significantly prolonged PT at time points up to 1 h, and aPTT at time points up to 0.25 h post-administration. Coagulation times were positively correlated with apixaban concentrations (PT R2 0.599, P < 0.0001; aPTT R2 0.430, P < 0.0001) and TF-TEG R-time was significantly prolonged 0.25 h post-administration. Following oral administration, mean bioavailability was 28.4%, lag time was 2 h, time to Cmax was 5 h and the apparent elimination half-life was 3.1 h. Oral apixaban significantly prolonged PT at 4, 6, and 8 h but aPTT and TF-TEG were not consistently affected by oral apixaban. Apixaban concentrations are best monitored using anti-Xa activity. Future studies should determine PK and bioactivity of other doses using commercial tablets and following multidose administration and establish safe, effective dosing ranges in sick dogs.

Utility of the Sonoclot analyzer to assess hyperfibrinolysis in dogs

BACKGROUND

Coagulation abnormalities, including hyperfibrinolysis, have been documented in sick veterinary patients. Viscoelastic tests, including the Sonoclot Coagulation and Platelet Function Analyzer, are useful in detecting hyperfibrinolysis. Tissue plasminogen activator (tPA) assays have been used to quantify fibrinolysis using thromboelastography.

OBJECTIVES

We aimed to document and evaluate changes in the whole blood of healthy dogs exposed to in vitro tPA at varying concentrations using the Sonoclot analyzer.

METHODS

Ten milliliters of blood was collected from healthy adult dogs. Sonoclot tests were run in duplicate and included a control sample and five tPA concentrations: 50, 75, 100, 150, and 200 IU/mL of blood.

RESULTS

Eleven dogs were enrolled in the study. Based on standard Sonoclot Signature changes, a numeric value fibrinolysis time (FTi) was derived to aid in the quantification of hyperfibrinolysis. Activated clotting time and clot rate Sonoclot values were not significantly affected by any tPA concentration. There was a significant decrease in platelet function (PF) at tPA concentrations equal to and above 75 IU/mL on channel 1 and tPA concentrations of 150 IU/mL and higher on channel 2. There was a progressive decrease in FTi at increasing tPA concentrations.

CONCLUSIONS

The Sonoclot analyzer can be used to evaluate hyperfibrinolysis. Predictable changes were seen in the Sonoclot Signature and a decrease in PF and FTi was found with increasing tPA concentrations. The Sonoclot assay with a tPA concentration of 100 IU/mL is suggested a baseline measure of hyperfibrinolysis and has a resultant median FTi of 42 minutes, which is a practical time for clinical applications.

Diagnosis of primary hyperfibrinolysis and in vitro investigation of the inhibitory effects of tranexamic acid in a group of dogs with sarcomas - A pilot study

Primary hyperfibrinolysis is not well characterised in canine cancer. This prospective case-control pilot study aimed to evaluate tissue plasminogen activator-modified thromboelastography (tPA-TEG) for diagnosis of primary hyperfibrinolysis in dogs with cancer and establish the in vitro therapeutic concentration of tranexamic acid (TXA). Nine dogs with sarcomas and normocoagulable thromboelastograms and 11 healthy dogs were included. For each a whole blood tPA-TEG, and four tPA-TEGs with added TXA in different concentrations were analysed. Lysis percentage at 30/60 min following maximal amplitude (LY30/60), clot lysis index (CL30/60), maximum rate of lysis (MRL), and total lysis (L) were investigated as diagnostic parameters of primary hyperfibrinolysis. In vitro TXA concentrations needed to inhibit 50% (IC50) and 90% (IC90) of the fibrinolytic potential were compared between groups. Significant primary hyperfibrinolysis (LY30 (P = 0.0001), LY60 (P = 0.003), CL30 (P = 0.01), and L (P = 0.02)) was observed in dogs with sarcomas. IC50 and IC90 of in vitro TXA for normalizing LY30 were 13.34 (SE 1.52) and 31.10 (SE 3.01) mg/L for dogs with sarcomas and 4.41 (SE 5.84) and 20.00 (SE 6.18) mg/L for healthy dogs. IC50 and IC90 for normalizing LY60 were 22.18 (SE 1.27) and 58.94 (SE 5.47) mg/L for dogs with sarcomas and 11.25 (SE 2.82) and 56.20 (SE 11.61) mg/L for healthy dogs. The IC50 for LY60 was significantly increased for dogs with sarcomas (P = 0.0003). Primary hyperfibrinolysis was documented by tPA-TEG in dogs with sarcomas. In vitro IC50 and IC90 for TXA were established. Clinical studies are required to establish therapeutic dosages in vivo.

Hemostatic capacity of canine chilled whole blood over time

OBJECTIVE

To determine the hemostatic potential of canine chilled whole blood maintained at clinically relevant storage conditions.

DESIGN

In vitro experimental study.

SETTING

Government blood and coagulation research laboratory and government referral veterinary hospital.

ANIMALS

Ten healthy Department of Defense military working dogs.

INTERVENTIONS

One unit of fresh whole blood was collected from each of 10 military working dogs using aseptic technique. Blood was maintained in a medical-grade refrigerator for 28 days at 4°C (39°F) and analyzed before refrigeration (day 0) and after (days 2, 4, 7, 9, 11, 14, 21, and 28).

MEASUREMENTS AND MAIN RESULTS

Ten units of canine blood were analyzed with whole blood platelet aggregation, thromboelastography, CBC, biochemical analysis, blood gas, and prothrombin/activated partial thromboplastin/fibrinogen assay. Clotting strength of chilled blood was maintained up to 21 days despite significant decreases in platelet aggregation to ADP, collagen, or γ-thrombin, significant prolongation of prothrombin and activated partial thromboplastin times, and reduced speed of clot formation (K time, alpha angle). Fibrinogen concentration, WBC, RBC, and platelet counts did not change over time.

CONCLUSIONS

Chilled canine whole blood loses a small percentage of clot strength through 21 days of refrigerated storage. Further research is needed to determine if this hemostatic potential is clinically relevant in hemorrhaging dogs who require surgical intervention or are exposed to traumatic events.

Thromboelastometry assessment of mycophenolate mofetil effect on thrombotic risk in dogs with primary and secondary immune-mediated hemolytic anemia and by Erhlichia canis infection

ABSTRACT This study aimed to identify, by means of thromboelastometry assessment, altered thrombotic risk in dogs with primary and secondary IMHA by E. canis infection after initiating the immunosuppressive therapy with mycophenolate mofetil. The animals’ screening was based on complete blood count (CBC), biochemical and urine tests. Dogs with moderate to severe anemia (hematocrit ≤ 25%) which showed symptoms of immune-mediated hemolysis, such as spherocytosis, positive saline agglutination, bilirubinuria and/or hemoglobinuria, were included. Blood and urine samples were collected at two different moments. The first sample (M1) was collected at the time of diagnosis, when hematocrit was lower or equal to 25% before treatment with mycophenolate mofetil (Accord ®); the second sample (M2) was collected after treatment with mycophenolate mofetil, when hematocrit was greater or equal to 30%. Five out of the twelve animals selected died before the end of the study. No reduction in thrombotic risk was observed in the animals treated with mycophenolate mofetil. The animals that presented hypocoagulation at the time of diagnosis showed the worst prognosis, and their reticulocyte count displayed a better prognostic value than their erythrocytes count at the time of diagnosis.

A systematic review of moxidectin as a treatment for parasitic infections in mammalian species

Moxidectin (MOX) is a macrocyclic lactone approved worldwide for the treatment of both endo- and ecto-parasites in many mammalian species. The aim of this study was to assess the efficacy of MOX as a treatment against parasites in a range of mammalian species. An electronic literature search was performed for publications to the 1^st September 2020. A total of 205 papers were retrieved and screened against all required criteria; hence, 35 were papers were reviewed in this study. The level of evidence and methodological quality was analysed, where a total of 13 publications were categorised as a 'randomised control trial', seven were categorised as a 'non-randomised control trial' and 15 as an 'experimental control trial'. The overall methodological quality of the publications was considered low, low to moderate, moderate, moderate to high and high in ten, four, twelve, five and a further four, respectively. We assessed the treatment and possible toxicity of MOX in 13 mammalian species, six investigations reported adverse effects to MOX in a small percentage of individuals. The authors reported observed reactions that were typically mild symptoms that did not require additional therapies, and/or resolved themselves. Further studies are needed to assess the efficacy of MOX treatment in a larger number of species, particularly in wildlife.

Hypercoagulability in dogs with chronic enteropathy and association with serum albumin concentration

BACKGROUND

Dogs with protein-losing enteropathy (PLE) are at risk of developing a hypercoagulable state, but the prevalence of hypercoagulability in dogs with chronic enteropathies (CE) and normal serum albumin concentration is unknown.

HYPOTHESIS

Dogs with CE are predisposed to a hypercoagulable state as assessed by thromboelastography (TEG) independent of serum albumin concentration.

METHODS

Dogs with chronic gastrointestinal signs from suspected inflammatory CE between 2017 and 2019 were included. Thirty-eight were evaluated; every dog had a CBC, serum biochemistry panel, and abdominal imaging performed. The Canine Inflammatory Bowel Disease Activity Index (CIBDAI) was calculated. Thromboelastography was performed at presentation, and reaction time (R), kinetic time (K), α-angle, maximal amplitude (MA), and global clot strength (G) were recorded. Dogs were considered hypercoagulable if the G value was ≥25% above the reference interval.

RESULTS

Seventeen of 38 (44.7%; 95% confidence interval [CI], 28.6-61.7%) dogs with CE were hypercoagulable. The G value did not differ between the 19 dogs with normal (≥28 g/L) serum albumin concentrations (9.05 kdyn/cm² ; 95% CI, 7.26-10.84; SD 3.71) and 19 dogs with hypoalbuminemia (11.3 kdyn/cm² ; 95% CI, 9.04-13.6, SD; 4.7; P = .11). The G value was negatively correlated with hematocrit, serum albumin concentration, and duration of signs and positively correlated with age.

CONCLUSIONS AND CLINICAL IMPORTANCE

Dogs with CE and normal serum albumin concentration can be hypercoagulable as measured by TEG.

Establishment of normal reference intervals in dogs using a viscoelastic point-of-care coagulation monitor and its comparison with thromboelastography

BACKGROUND

Viscoelastic coagulation devices are a useful adjunct to the evaluation of hemostasis in veterinary patients. VCM Vet is a point-of-care device that is simple in operation and could be used to diagnose and trend hemostatic abnormalities in sick patients. VCM Vet does not use activators.

OBJECTIVES

We aimed to establish reference intervals (RIs) for VCM Vet in a healthy adult canine population and concurrently perform thromboelastographic (TEG) analysis on these samples with and without tissue factor (TF) activation for RI comparisons.

METHODS

Duplicate VCM Vet tests were performed immediately upon sample collection. Two concurrent TEG tests were performed on the remaining blood, one citrated, untreated (CU), and one activated with TF at a 1:3600 dilution.

RESULTS

Fifty-two dogs were enrolled in the study. The following RIs were generated for VCM Vet machine 1 and 2, respectively: clot time (CT) (seconds) 163-480 and 172-457; clot formation time (CFT) (seconds) 104-288 and 94-252, α-angle (degrees) 41-65 and 44-66, and maximum clot firmness (MCF) (no units) 27-43 and 30-46. Moderate to good correlations were observed between the two machines with Lin's concordance correlation coefficients of 0.51-0.9 and a P < 0.002. TEG RIs were similar to previously reported values.

CONCLUSIONS

VCM Vet RIs were generated. Each VCM Vet device should have a unique RI established due to inter-device variability. Direct correlations of VCM Vet values with TEG parameters were not performed due to the narrow range of the normal values and the need to evaluate patients with a wide range of hemostatic abnormalities.

Effect of rest temperature on rotational thromboelastometry in New Zealand White rabbits

With the increasing popularity of viscoelastic coagulation analyzers, such as rotational thromboelastometry [ROTEM] and thromboelastography, the need for standardized methodology for appropriate interpretation has become increasingly important. Viscoelastic analysis is heavily influenced by a multitude of pre-analytic factors, both in vivo and in vitro, leading to a large amount of variation between institutions. We investigated the effect of room temperature during a 30-min sample rest time on ROTEM, which analyzed both intrinsic and extrinsic pathways. We also evaluated the feasibility of using ROTEM to assess coagulation in non-anesthetized domestic rabbits. Rabbits were selected because they are a common companion animal that could benefit from the use of viscoelastic analysis for various disease processes that could lead to coagulopathies. Citrated whole blood was collected from 10 rabbits and allowed to rest upright for 30 min either at room temperature (~ 21°C) or in a tube warmer (37°C) before analysis. There was no significant difference in results between room temperature and warmed samples, which suggests that allowing samples to rest at room temperature is acceptable clinically. Additionally, blood collection and analysis were feasible in all rabbits.

A prospective randomized open-label trial on the comparative effects of 6% hydroxyethyl starch 130/0.4 versus polyionic isotonic crystalloids on coagulation parameters in dogs with spontaneous hemoperitoneum

OBJECTIVE

To evaluate the effects of 6% hydroxyethyl starch 130/0.4 (HES) and a polyionic isotonic crystalloid (CRYS) on standard coagulation tests and rotational thromboelastometry (ROTEM) in dogs with spontaneous hemoperitoneum (SHP).

DESIGN

Prospective randomized open-label clinical study.

SETTING

University teaching hospital.

ANIMALS

Forty-two client-owned dogs presented with SHP.

INTERVENTIONS

Dogs diagnosed with SHP and hypovolemic shock were randomly allocated to receive HES (10 mL/kg, n = 22) or CRYS (30 mL/kg, n = 20) intravenously over 20 minutes for hemodynamic stabilization.

MEASUREMENTS AND MAIN RESULTS

Parameters measured before (T₀ ) and after (T₁ ) treatment were HCT, platelet counts, prothrombin time, activated partial thromboplastin time, fibrinogen concentrations, and extrinsic activated (EXTEM), intrinsic activated (INTEM), and extrinsic activated with platelet inhibition ROTEM assays. Data were analyzed as absolute values and as the percentage change from T₀ to T₁ . No significant differences between groups were detected in any variable at T₀ , and for HCT, platelet counts, prothrombin time, activated thromboplastin time, and fibrinogen concentrations at T₁ . Clot formation time in EXTEM was significantly prolonged (P = 0.037), and maximum clot firmness was significantly decreased (P = 0.038) in the HES group compared to the CRYS group at T₁ . The percentage change in EXTEM clotting time (P = 0.012) and INTEM clot formation time (P = 0.031) was greater after HES than CRYS. Lysis indices remained at 100% for all ROTEM assays in both groups.

CONCLUSION

Compared to a 3-fold volume of CRYS, administration of HES was associated with impairment in ROTEM parameters in dogs with SHP, but no evidence of hyperfibrinolysis was detected.

Lyophilized platelets versus cryopreserved platelets for management of bleeding in thrombocytopenic dogs: A multicenter randomized clinical trial

Background

Thrombocytopenia in dogs is common in critical care medicine, but availability of fresh platelet concentrates in veterinary medicine can be limiting. Lyophilized platelets have long shelf‐lives and can be easily transported, stored, and administered in various settings.

Objective

To evaluate the efficacy and safety of a novel trehalose‐stabilized canine lyophilized platelet product in thrombocytopenic dogs with clinically‐evident bleeding.

Animals

Eighty‐eight dogs with platelet counts <50 × 10³/μL and a standardized bleeding assessment tool (DOGiBAT) score ≥2.

Methods

Multicenter, randomized, non‐blinded, non‐inferiority clinical trial comparing dimethyl sulfoxide (DMSO)‐stabilized cryopreserved platelet concentrates (CPP) with trehalose‐stabilized lyophilized platelets (LP) for control of bleeding in thrombocytopenic dogs. Dogs were randomized to receive 3 × 10⁹ platelets/kg of LP or CPP. Primary outcome measures were change in DOGiBAT score, platelet count, need for additional red cell transfusion and all‐cause mortality.

Results

Fifty dogs received LP and 38 received CPP. Baseline demographics and clinical characteristics of both groups were comparable. At 1‐hour post‐transfusion, LP were superior for change in DOGiBAT score, and non‐inferior at 24‐hours post‐transfusion. The LP were non‐inferior to CPP for change in platelet count, need for additional red blood cell units, and survival to discharge. The LP were superior for change in hematocrit at 1‐hour post‐transfusion, and non‐inferior at 24‐hours. No adverse effects were noted in either group.

Conclusions and Clinical Importance

A novel trehalose‐stabilized canine LP product appears to be logistically superior and is clinically non‐inferior to DMSO‐stabilized canine CPP for management of bleeding in thrombocytopenic dogs.

Respiratory Emergencies

Respiratory distress is commonly seen in dogs and cats presenting to the emergency room. Rapid identification of respiratory difficulty with strategic stabilization and diagnostic efforts are warranted to maximize patient outcome. This article focuses on the relevant anatomy and physiology of the respiratory system and the clinical recognition, stabilization, and initial diagnostic planning for small animal patients that present for respiratory emergencies.

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.

A Novel Microchip Flow Chamber (Total Thrombus Analysis System) to Assess Canine Hemostasis

Hemorrhagic diseases are common in dogs. Current coagulation assays do not model all aspects of in vivo hemostasis and may not predict bleeding risk. The Total-Thrombus Analysis System (T-TAS) is a novel hemostasis assay system in which whole blood flows through microfluidic channels at defined shear rates to provide qualitative and quantitative evaluation of platelet function (PL-chip) and coagulation function (AR-chip). The present study evaluated the T-TAS in dogs with hereditary bleeding disorders and with acquired hemorrhagic syndromes (Group 1), and healthy controls (Group 2). Hereditary defects included von Willebrand's disease (VWD; n = 4), hemophilia A (n = 2), and canine Scott syndrome (n = 2). Acquired hemorrhagic disorders included neoplastic hemoperitoneum (n = 2) and acute hemorrhagic diarrhea syndrome (n = 1). Citrate anticoagulated samples were collected from diseased dogs (Group 1, n = 11) and controls (Group 2, n = 11) for coagulation screening tests, fibrinogen analyses, D-dimer concentration, antithrombin activity, von Willebrand Factor antigen, PFA-100 closure time (PFA-CT), and thromboelastography (TEG). Citrate and hirudin anticoagulated samples were used for T-TAS analyses at two shear rates. Qualitative thrombus formation in each chip was recorded using the T-TAS video camera. Numeric parameters, derived from the instrument software, included occlusion start time (OST; time to 10 kPa), occlusion time (OT; time to 60 kPa (PL-chip) or 80 kPa (AR-chip)), and area under the pressure curve (AUC). Correlations between continuous variables were evaluated by Spearman's rank. Continuous variables were compared between groups by Student's t-test or the Mann-Whitney U-test. Alpha was set at 0.05. In combined analyses of all dogs, significant correlations were identified between T-TAS variables, between the PFA-CT and PL-chip parameters and between TEG variables and AR-chip parameters. The prothrombin time correlated with the AR-chip AUC at both shear rates. In Group 1 dogs, the AR-chip AUC at low shear was significantly reduced compared with Group 2 dogs. Aberrant thrombus formation was seen in video images recorded from dogs with VWD and hemophilia A. The T-TAS AR-chip analysis distinguished dogs with bleeding risk compared to healthy controls. Initial evaluations of the T-TAS suggest it may aid characterization of hemostasis in patients at-risk of bleeding and assist with delineating bleeding phenotypes.

Reference Intervals for and the Effects of Sample Handling and Sex on Rotational Thromboelastometry in Healthy Adult Pigs

Accurate assessment of coagulation in porcine studies is essential. We sought to establish normal values for porcine rotational thromboelastometry (ROTEM) according to the American Society for Veterinary Clinical Pathology guidelines and to assess the effects of various preanalytical parameters on those measurements. Healthy Yorkshire-cross pigs (n = 81; 46 males and 35 females) were anesthetized. By using a 18-gauge needle attached to a vacuum phlebotomy tube, blood was acquired from the cranial vena cava. Tubes were filled in the following order: evacuation clot tube, EDTA tube, heparin tube, and 2 citrate tubes. The citrate tubes were randomly assigned to 30 min with or without constant agitation on a rocker. The following parameters were reported according to the manufacturer's recommendations: clotting time, clot formation time, α, (tangent to the clot formation curve when the clot firmness is 20 mm), clot firmness after 10 and 20 min, maximal clot firmness, maximum lysis, and lysis indexes at 30 and 45 min. Reference intervals were reported as mean ± 2 SD (parametric distribution) or 2.5th and 97.5th percentile of the population's results (nonparametric distribution). The effects of sex, sampling order, and agitation on ROTEM results were analyzed through linear regression. Neither sex nor sample agitation influenced any of the ROTEM parameters. Combined reference intervals were established for each ROTEM parameter by pooling data from the nonagitated tubes for both male and female pigs. This study is the first to establish ROTEM reference intervals from a large number of male and female adult Yorkshire-cross pigs and to provide a detailed description of preanalytical sample processing.

In vitro effects of lactated Ringer's solution, hypertonic saline, hydroxyethyl starch, hypertonic saline/hydroxyethyl starch, and mannitol on thromboelastographic variables of canine whole blood

OBJECTIVE

To assess the in vitro effects of crystalloid and colloid IV fluids on the thromboelastographic (TEG) variables of canine whole blood.

DESIGN

In vitro experimental study.

SETTING

Veterinary teaching hospital.

ANIMALS

Twenty-two healthy dogs.

INTERVENTION

Citrated whole blood samples collected from healthy dogs were diluted with 3.4% hypertonic saline (HTS 3.4), 7% hypertonic saline (HTS 7), and 20% mannitol at 8% and 16% dilutions; hydroxyethyl starch 130/0.4 (HES 130/0.4) at 16% dilution; lactated Ringer's solution (LRS) at 16%, 33%, and 66% dilutions; and HTS 7-HES 130/0.4 at 25% and 50% dilutions. Kaolin-activated TEG analysis was concurrently performed on diluted and control (undiluted) samples.

MEASUREMENTS AND MAIN RESULTS

Dilution of canine whole blood with LRS compared to control reduced α angle and MA at both 33% (P = 0.009 and P = 0.011, respectively) and 66% dilution (P < 0.001 and P < 0.001, respectively), and prolonged K time at 66% dilution (P = 0.003). At 16% dilution, HTS 3.4, prolonged R time (P = 0.007), while mannitol, a fluid iso osmolar to HTS 3.4, prolonged K time (P = 0.006), reduced α angle (P < 0.001), MA (P = 0.046), and LY60 (P = 0.015). At 8% dilution, HTS 7, a fluid of high osmolarity and tonicity, prolonged R time (P = 0.009) and reduced MA (P = 0.015), while all measured TEG variables were altered at the 16% dilution (P < 0.01 for all variables). HES 130/0.4 reduced α angle (P = 0.031) and MA (P = 0.001) and increased LY60 (P < 0.001) at 16% dilution. Comparing different fluid types, HES 130/0.4 and HTS 3.4 had no to minor, mannitol intermediate, and HTS 7 profound effects on TEG variables (P < 0.05) when compared to LRS at the same dilution.

CONCLUSIONS

In vitro dilution of canine whole blood with commonly used IV fluids leads to thromboelastographic changes consistent with hypocoagulability in a dose dependent manner for all fluid types tested. Viscoelastic changes are also influenced by fluid characteristics, specifically tonicity and osmolarity.

Hematological and Hemostatic Alterations Associated With a Single Extracorporeal Renal Replacement Therapy in Dogs With Acute Kidney Injury Associated Leptospirosis: A Pilot Study

Extracorporeal renal replacement therapy (ERRT) used in dogs with acute kidney injury (AKI) may be associated with hematological and hemostatic disorders. However, its characteristics are not fully described in dogs. The purpose of this pilot study was to characterize the impact of ERRT on hematological, hemostatic, and thromboelastometric parameters in dogs with AKI. We conducted a prospective observational single cohort study in 10 client-owned dogs with AKI associated leptospirosis undergoing ERRT. Results from the CBC, coagulation tests (prothrombin and activated partial thromboplastin times [aPTT]) and rotational thromboelastometry (TEM; intrinsic TEM [inTEM] and heparinase-based TEM [hepTEM]) were recorded before and after the first ERRT session. Blood abnormalities observed before the ERRT session included thrombocytopenia (10/10), anemia (8/10), leukocytosis (4/10), prolonged aPTT (4/10) and leukopenia (1/10). After ERRT, the platelet count decreased (-25%; P = .012) whereas leukocytes (+15%; P = .046) and aPTT (+24%; P = .006) increased. The clotting time (CT) on inTEM assay and the relative variation of CT based on inTEM and hepTEM profiles increased after the ERRT session (P = .037 and P = .048, respectively). Seven dogs, 2 dogs, and 1 dog were defined as having a normal, hypocoagulable, and hypercoagulable inTEM profile after ERRT, respectively. After ERRT, no hepTEM parameter was significantly different from before treatment. Platelet count, leukocytes, aPTT and CT were altered after the first ERRT session. Beyond the hemostatic abnormalities expected by the use of UFH, thrombocytopenia appears as the only hemostatic change after a single ERRT session in dogs with AKI.

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.

Influence of needle gauge and venepuncture difficulty on thromboelastography in healthy cats

OBJECTIVES

The aim of this study was to evaluate the effect of two differently sized butterfly catheter needles and the effect of venepuncture difficulty on thromboelastography (TEG) results in healthy cats.

METHODS

Twenty-four healthy cats were included. Blood samples were collected from the jugular vein by syringe aspiration via direct venepuncture with 21 G and 22 G butterfly needles. The venepuncture difficulty score was classified into four categories. The first 1.5 ml blood drawn from each subject was discarded before collecting a sample for TEG analysis. TEG analyses were performed on citrated whole blood samples from 17 clinically healthy cats, using assays with kaolin as activators. Among the TEG parameters, reaction time (R), clot formation time (κ), alpha angle (α), maximum amplitude (MA) and global clot strength (G) were recorded from each tracing.

RESULTS

Seven cats were excluded from the study; results were obtained for the remaining 17 cats. There were no statistically significant differences between the use of two different needles for R (P = 0.72), κ (P = 0.74), α (P = 0.99), MA (P = 0.08) and G (P = 0.09). Samples with difficulty scores ⩾1 were not significantly different from samples with difficulty scores of 0 for R (P = 0.24), κ (P = 0.65), α (P = 0.65), MA (P = 0.72) and G (P = 0.77).

CONCLUSIONS AND RELEVANCE

The results of TEG in clinically healthy cats do not differ significantly when using two different gauge needles. There was no significant difference in the TEG results according to venepuncture difficulty scoring.

American College of Veterinary Emergency and Critical Care (ACVECC) Consensus on the Rational Use of Antithrombotics in Veterinary Critical Care (CURATIVE) guidelines: Small animal

OBJECTIVES

To systematically review available evidence and establish guidelines related to the risk of developing thrombosis and the management of small animals with antithrombotics.

DESIGN

Standardized, systematic evaluation of the literature (identified by searching Medline via PubMed and CAB abstracts) was carried out in 5 domains (Defining populations at risk; Defining rational therapeutic use; Defining evidence-based protocols; Refining and monitoring antithrombotic therapies; and Discontinuing antithrombotic therapies). Evidence evaluation was carried out using Population, Intervention, Comparison, Outcome generated within each domain questions to address specific aims. This was followed by categorization of relevant articles according to level of evidence and quality (Good, Fair, or Poor). Synthesis of these data led to the development of a series of statements. Consensus on the final guidelines was achieved via Delphi-style surveys. Draft recommendations were presented at 2 international veterinary conferences and made available for community assessment, review, and comment prior to final revisions and publication.

SETTINGS

Academic and referral veterinary medical centers.

RESULTS

Over 500 studies were reviewed in detail. Worksheets from all 5 domains generated 59 statements with 83 guideline recommendations that were refined during 3 rounds of Delphi surveys. A high degree of consensus was reached across all guideline recommendations.

CONCLUSIONS

Overall, systematic evidence evaluations yielded more than 80 recommendations for the treatment of small animals with or at risk of developing thrombosis. Numerous significant knowledge gaps were highlighted by the evidence reviews undertaken, indicating the need for substantial additional research in this field.

Influence of needle gauge used for venipuncture on measures of hemostasis in cats

OBJECTIVES

The objective of this study was to evaluate the effect of different needle sizes used to obtain blood via jugular venipuncture in cats on routine measures of hemostasis.

METHODS

This was a prospective, observational, randomized, clinical study carried out at a university teaching hospital. Twenty healthy, client-owned cats were used. Each cat had blood collected via direct venipuncture from both jugular veins. Sampling of the right and left jugular vein was randomized to be collected with either a 22 G or a 25 G needle, respectively, and routine coagulation variables and platelet count were performed on all samples. Values were analyzed for differences in needle size, and site of sample collection.

RESULTS

There was no difference between the two needle gauges in activated partial thromboplastin time, platelet count, fibrinogen degradation products, or fibrinogen, or between sampling from the left and right jugular vein. Prothrombin time (PT) was significantly higher when drawn from a 25 G needle (11.7 s) compared with a 22 G needle (11.4 s) ( P = 0.01), but not different in left vs right jugular vein samples. Bland-Altman analysis of PT comparing for 25 G minus 22 G needle vs the average, calculated a mean bias (95% limits of agreement) of 0.49 s (-1.4 s to 2.4 s).

CONCLUSIONS AND RELEVANCE

This study of 20 healthy cats found that the use of either a 25 G or 22 G needle for jugular venipuncture did not introduce any clinically meaningful difference in routine coagulation variables or platelet count.