Biological variation of thromboelastrography variables in 10 clinically healthy horses

Scruggs, Jennifer L.; Flatland, Bente; McCormick, Karen A.; Reed, Ann M.

doi:10.1111/vec.12410

Cited by 8 publications

(7 citation statements)

References 22 publications

(34 reference statements)

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“…This could not be attributed to an inadequate washout period, because some of the lowest results for thrombin generation in the individual horses occurred after placebo treatment. The variability observed in both platelet activation and thrombin generation assays at baseline and after treatment with placebo may be due to inherent biological variation in hemostasis in horses, as has been reported for viscoelastic-based hemostasis testing in horses ( 33 ) and for hemostasis testing in people ( 34 ). Because the total amount of thrombin generated did not explain the differences in the baseline platelet responses to agonists in individual horses, the biological variation is likely to be intrinsic to coagulation factors that trigger or drive thrombin generation, inhibitors of hemostasis, and platelets themselves ( 34 ).…”

Section: Discussionmentioning

confidence: 90%

Subcutaneous Administration of Low-Molecular-Weight Heparin to Horses Inhibits Ex Vivo Equine Herpesvirus Type 1-Induced Platelet Activation

et al. 2018

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Equine herpesvirus type 1 (EHV-1) is a major cause of infectious respiratory disease, abortion and neurologic disease. Thrombosis in placental and spinal vessels and subsequent ischemic injury in EHV-1-infected horses manifests clinically as abortion and myeloencephalopathy. We have previously shown that addition of heparin anticoagulants to equine platelet-rich plasma (PRP) can abolish ex vivo EHV-1-induced platelet activation. The goal of this study was to test whether platelets isolated from horses treated with unfractionated heparin (UFH) or low-molecular-weight heparin (LMWH) were resistant to ex vivo EHV-1-induced activation. In a masked, block-randomized placebo-controlled cross-over trial, 9 healthy adult horses received 4 subcutaneous injections at q. 12 h intervals of one of the following treatments: UFH (100 U/kg loading dose, 3 maintenance doses of 80 U/kg), 2 doses of LMWH (enoxaparin) 80 U/kg 24 h apart with saline at the intervening 12 h intervals, or 4 doses of saline. Blood samples were collected before treatment and after 36 h, 40 h (4 h after the last injection) and 60 h (24 h after the last injection). Two strains of EHV-1, Ab4 and RacL11, were added to PRP ex vivo and platelet membrane expression of P selectin was measured as a marker of platelet activation. Drug concentrations were monitored in a Factor Xa inhibition (anti-Xa) bioassay. We found that LMWH, but not UFH, inhibited platelet activation induced by low concentrations (1 × 106 plaque forming units/mL) of both EHV-1 strains at 40 h. At this time point, all horses had anti-Xa activities above 0.1 U/ml (range 0.15–0.48 U/ml) with LMWH, but not UFH. By 60 h, a platelet inhibitory effect was no longer detected and anti-Xa activity had decreased (range 0.03 to 0.07 U/ml) in LMWH-treated horses. Neither heparin inhibited platelet activation induced by high concentrations (5 × 106 plaque forming units/mL) of the RacL11 strain. We found substantial between horse variability in EHV-1-induced platelet activation at baseline and after treatment. Minor injection site reactions developed in horses given either heparin. These results suggest that LMWH therapy may prevent thrombotic sequelae of EHV-1, however further evaluation of dosage regimens is required.

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Section: Discussionmentioning

confidence: 90%

Subcutaneous Administration of Low-Molecular-Weight Heparin to Horses Inhibits Ex Vivo Equine Herpesvirus Type 1-Induced Platelet Activation

et al. 2018

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“…However, the method is not as common in veterinary medicine as in human medicine even though the test is not species-dependent. In recent years, the number of studies on equine thromboelastography has been slowly rising (e.g., Epstein et al 2009;Mendez-Angulo et al 2010;Epstein et al 2011;Hyldahl-Laursen et al 2013;Scruggs et al 2016), but the physiological values required for the clinical use of this method are still unknown. Further testing, including comparison of thromboelastography and standard coagulation testing, is required.…”

mentioning

confidence: 99%

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

Machackova¹,

Boselova²,

Vanova³

et al. 2018

Vet. Med. - Czech

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

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“…Use in non‐hospitalised cases has been limited as the assay is best performed shortly after blood collection as storage, length of rest period and sample agitation can affect results (Jamieson et al., 2018; Lemon et al., 2021). In addition, clinical use in horses has so far been hampered by large inter‐individual variability of parameters between horses and also inter‐ and intra‐operator variability between staff performing the assay (Dunkel et al., 2010; Epstein et al., 2009; Scruggs et al., 2016; Thane et al., 2017). While the clinical potential of viscoelastographic methods still needs to be fully explored, recent investigations show more promising results for the development of a meaningful stable site‐based assessment of hypo‐ and hypercoagulative states.…”

Section: Assessment Of Coagulationmentioning

confidence: 99%

Hypercoagulation and thrombosis associated with infection in horses

Dunkel

2021

Equine Veterinary Education

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Biological variation of thromboelastrography variables in 10 clinically healthy horses

Abstract: PRIs are appropriate for TEG variables, R, angle, and MA when interpreting results from individual horses based on calculated IOI values equal to or greater than 1.4. PRIs are likely appropriate when interpreting K, but IOI could not be calculated for this variable.

Cited by 8 publications

References 22 publications

Subcutaneous Administration of Low-Molecular-Weight Heparin to Horses Inhibits Ex Vivo Equine Herpesvirus Type 1-Induced Platelet Activation

Subcutaneous Administration of Low-Molecular-Weight Heparin to Horses Inhibits Ex Vivo Equine Herpesvirus Type 1-Induced Platelet Activation

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

Hypercoagulation and thrombosis associated with infection in horses

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