Omneity® Pellets
All-In-One Vitamin & Mineral Pellet
Topic:Hemostasis
Hemostasis in horses refers to the physiological process that stops bleeding and maintains blood in a fluid state within the vascular system. It involves a complex interaction between the vascular endothelium, platelets, and the coagulation cascade, which work together to form a stable blood clot following vascular injury. This process is essential for preventing excessive blood loss and ensuring wound healing. Key components of equine hemostasis include coagulation factors, fibrin formation, and platelet aggregation. Understanding the mechanisms and regulation of hemostasis in horses is important for diagnosing and managing bleeding disorders and other related conditions. This page compiles peer-reviewed research studies and scholarly articles that explore the mechanisms, regulation, and clinical implications of hemostasis in equine medicine.
Evaluation of contact activation of citrated equine whole blood during storage and effects of contact activation on results of recalcification-initiated thromboelastometry. To evaluate the degree of activation of the contact pathway in citrated equine whole blood over holding times ≤ 30 minutes and assess effects of contact activation on recalcification-initiated thromboelastometry. Methods: 11 healthy adult mixed-breed horses. Methods: Blood was collected by atraumatic jugular venipuncture into prewarmed evacuated siliconized glass tubes containing citrate anticoagulant and held at 37°C for ≤ 30 minutes. Thromboelastometry was performed with an in vitro viscoelasticity (thromboelastometry) monitoring system. Factor XII and factor XI procoagulant activities ...
Inhibition of platelet function with clopidogrel, as measured with a novel whole blood impedance aggregometer in horses. This study aimed to validate a loading and maintenance clopidogrel dosing scheme for the inhibition of platelet function, measured by whole blood impedance aggregometry in healthy adult horses. Ten Warmblood horses received oral clopidogrel once daily. Doses were based on 50 kg weight categories and resulted in one loading dose of 6-6.5 mg/kg bodyweight and maintenance doses of 1.2-1.4 mg/kg over the next 4 days. Platelet function was measured via whole blood multiple electrode impedance aggregometry prior to (T0) and at 6, 12, 24, 48, 72, 96, 144, 192 and 240 h following the loading d...
Changes in platelet morphology and function during 24 hours of storage. For in vitro studies assessing the interaction of platelets with implant materials, common and standardized protocols for the preparation of platelet rich plasma (PRP) are lacking, which may lead to non-matching results due to the diversity of applied protocols. Particularly, the aging of platelets during prolonged preparation and storage times is discussed to lead to an underestimation of the material thrombogenicity. Here, we study the influence of whole blood- and PRP-storage times on changes in platelet morphology and function. Blood from apparently healthy subjects was collected according...
A comparison of peritoneal fluid values in mares following bilateral laparoscopic ovariectomy using a vessel sealing and dividing device versus placement of two ligating loops. The objective of this study was to determine the effect of bilateral laparoscopic ovariectomy on peritoneal fluid values in mares and compare how this effect was modified by the method of ovarian vessel hemostasis used. Ten mares undergoing standing bilateral laparoscopic ovariectomy were used in a randomized clinical study. During surgery, blood vessels within the mesovarium were either: (1) sealed and transected with a vessel sealing and dividing device (VSDD), or (2) ligated using two loops placed proximal to each ovary and then the mesovarium transected using laparoscopic scissors. The ova...
Progression of plasma D-dimer concentration and coagulopathies during hospitalization in horses with colic. To assess the progression of plasma D-dimer concentrations and coagulation status in horses with different types of colic. Methods: Prospective clinical observational study performed between March 2004 and September 2008. Methods: Veterinary university teaching hospital. Methods: Horses admitted and treated for colic and hospitalized for >48 hours were considered. Animals were classified by diagnosis into medical obstructive conditions (MO), surgical obstructive conditions (SO), inflammatory conditions, and ischemic lesions (IS). Methods: Three blood samples were obtained from each horse (a...
Effects of clopidogrel on horses with experimentally induced endotoxemia. To evaluate the effects of clopidogrel on clinical and clinicopathologic variables in healthy horses with experimentally induced endotoxemia. Methods: 12 adult mares. Procedures-Horses were assigned with a randomization procedure to receive clopidogrel (4 mg/kg, once, then 2 mg/kg, q 24 h; n = 6) or a placebo (6) through a nasogastric tube. After 72 hours of treatment, horses received lipopolysaccharide (LPS; 30 ng/kg, IV). Heart rate, respiratory rate, rectal temperature, CBC variables, plasma fibrinogen concentration, serum tumor necrosis factor-α concentration, plasma von Willebrand factor...
Parallel alternating sliding knots are effective for ligation of mesenteric arteries during resection and anastomosis of the equine jejunum. In literature only one article describes and compares methods of achieving hemostasis in equine mesenteric arteries during jejunal resection and anastomosis, and most textbooks favor ligating-dividing mechanical devices. The latter method cannot always be used, not least because the devices are expensive and in some cases even contra-indicated. Various types of knots, including sliding knots, are widely used to provide hemostasis in laparoscopy. Methods: Portions of jejunum with associated mesenteric vessels were collected from 12 horses at a local abattoir. These were divided into 24 specimen...
Coagulopathies in horses. Although primary coagulopathies are rare in horses, changes in coagulation and fibrinolysis are commonly associated with inflammatory diseases. A clear understanding of the pathophysiology of normal and abnormal hemostasis is required to be able to choose and interpret diagnostic tests evaluating coagulation and fibrinolysis. After diagnosis, treatment of the underlying disease must occur regardless of whether clinical manifestations (excessive bleeding or thrombosis) of the coagulopathy are present or not. Specific treatment may be initiated if there are clinical signs of coagulopathy.
Acute hemorrhage and blood transfusions in horses. Treatment of acute hemorrhage in the horse involves targeted medical management and also may involve surgical stabilization. This article provides an approach to the initial stabilization and information on available topical hemostats. The practice of blood collection and transfusion is also described, with attention to new information on viability of transfused equine blood, potential negative effects of blood transfusion, and methods of cell salvage.
Coagulation, oncotic and haemodilutional effects of a third-generation hydroxyethyl starch (130/0.4) solution in horses. Clinical indications for hydroxyethyl starches (HES) in horses include rapid plasma volume expansion and oncotic support during periods of hypoproteinaemia. Side effects such as coagulopathies associated with HES administration pose limitations to their use in veterinary medicine. In man, tetrastarch (130/0.4) has demonstrated less profound effects on coagulation compared with first- and second-generation HES. Objective: To evaluate the haemostatic and oncotic effects of tetrastarch (130/0.4) administered at 10, 20 and 40 ml/kg bwt in healthy horses. Methods: Randomised crossover experiment....
Systematic evaluation of evidence on veterinary viscoelastic testing part 1: System comparability. To systematically examine the evidence on system comparability between the thromboelastography and the rotational thromboelastometry viscoelastic point-of-care instruments and to identify knowledge gaps. Methods: Standardized, systematic evaluation of the literature, categorization of relevant articles according to level of evidence and quality, and development of consensus on conclusions for application of the concepts to clinical practice. Methods: Academic and referral veterinary medical centers. Results: Medline via PubMed, CAB abstracts, and Google Scholar were searched. A total of 8 rele...
Hemostatic profile during late pregnancy and early postpartum period in mares. Hemostasis is a physiological process that prevents excessive blood loss and represents a protective mechanism at the time of delivery. Peripartum hemorrhage is a recurring hazardous condition to mare's health; therefore, we aimed to study mares' hemostatic profile to investigate whether physiological adjustments occur during late pregnancy and early postpartum. Fifteen pregnant mares have been monitored from the 34th week of pregnancy until the third week after foaling. Fifteen nonpregnant mares were used as control group. Jugular blood samples were analyzed for platelet count (Plt), prothrom...
Cardiovascular, colloid osmotic pressure, and hemostatic effects of 2 formulations of hydroxyethyl starch in healthy horses. Lower molecular weight and molar substitution formulations of hydroxyethyl starch (HES) solutions might maximize cardiovascular function and colloid osmotic pressure (COP) and minimize adverse effects on coagulation. Objective: To compare effects of 1 low and 1 high molecular weight and molar substitution HES solution on cardiovascular variables, COP, and hemostasis in normal horses. Methods: Eight healthy adult horses. Methods: Randomized, crossover designed study: 10 mL/kg bolus of 6% HES (600/0.75) (hetastarch) (HS), 6% HES (130/0.4) tetrastarch (TS), and 0.9% NaCl (NS). Variables recorded ...
Training-induced changes in clotting parameters of athletic horses. The purpose of this study was to investigate the effects of training on prothrombin time, activated partial thromboplastin time, and fibrinogen (Fb) concentrations in horses to assess potential adaptive response to training. Fifteen clinically healthy horses were enrolled in the present study and equally divided into three groups. Group A completed an intense training program, group B participated in a light training program, and group C included sedentary horses. After 5 weeks, group B was subjected to the same training program completed by group A and renamed group B1. Blood samples were col...
Therapeutic plasma concentrations of epsilon aminocaproic acid and tranexamic acid in horses. Antifibrinolytic drugs such as epsilon aminocaproic acid (EACA) and tranexamic acid (TEA) are used to treat various bleeding disorders in horses. Although horses are hypofibrinolytic compared to humans, dosing schemes have been derived from pharmacokinetic studies targeting plasma concentrations in humans. Objective: We hypothesized therapeutic plasma concentrations of antifibrinolytic drugs in horses would be significantly lower than in humans. Our objective was to use thromboleastography (TEG) and an in vitro model of hyperfibrinolysis to predict therapeutic concentrations of EACA and TEA in...
Plasma D-dimer concentrations during experimental EHV-1 infection of horses. Central nervous system blood vessel thrombosis is a part of the pathogenesis of equid herpesvirus-associated myeloencephalopathy (EHM). D-dimers (DD) are stable breakdown products of cross-linked fibrin, and increased DD-plasma concentrations could reflect the degree of systemic coagulation during EHV-1 infection. Objective: We hypothesized that blood DD concentrations will be increased during periods of EHV-1 fever and viremia, reflecting an activated coagulation cascade with fibrinolysis. Methods: Twenty-eight equids were infected with EHV-1 in 3 experimental infection studies. Three (uninfe...
Comparison of components of biological variation between 3 equine thromboelastography assays. There is a paucity of information about the analytical performance of thromboelastography (TEG) in horses, specifically concerning components of variation among different analytical methods. Such data may be obtained by nested analysis of repetitive standardized sampling of healthy individuals. Objective: The objectives were (1) to assess the relative susceptibility to sources of preanalytical variation in a highly standardized setting, (2) to directly compare and evaluate the observed analytical variation, and (3) to assess the applicability of population-based reference intervals. Methods: B...
Serial viscoelastic and traditional coagulation testing in horses with gastrointestinal disease. Objectives of this study were to compare the ability of serial thromboelastography, Sonoclot, and traditional coagulation panels to detect coagulopathies associated with disease category, systemic inflammatory response syndrome (SIRS), complications, and nonsurvival in horses with gastrointestinal disease. Methods: Prospective clinical evaluation. Methods: University referral hospital. Methods: One hundred twenty-one horses admitted as emergencies for gastrointestinal disease and 28 healthy adult horses. Methods: Blood samples were collected ≤4 times from emergency horses (admission and if s...
Changes in blood coagulation induced by exercise training in young athletic horses. Prothrombin Time (PT), Activated Partial Prothrombin Time (APTT), Fibrinogen concentration (Fbg) and Platelet number (Plt) were evaluated in 20 young athletic horses during a training program. A standardized exercise test (SET) was performed every month for three months. The V4 variations (the speed, in m/min, reached at the blood lactate concentration of 4 mmol/l) obtained for each test were calculated to assess the effect of training program on athletic performance. Blood samples were collected at 20-day intervals over a period of 80 days from the beginning of the training program. The V4 (P...
Jugular thrombophlebitis in horses: a review of fibrinolysis, thrombus formation, and clinical management. Thrombophlebitis of the jugular vein is commonly observed in horses, particularly during intensive care, and leads to local and systemic inflammatory responses as well as head and neck circulatory impairment. Thrombolytic therapy is widely used in human practice with the aim of thrombus dissolution and recanalization of the injured vessels. There are similarities between human and horse coagulation and fibrinolytic processes. This review examines the fibrinolytic system, thrombus formation, and the clinical management of jugular thrombophlebitis, including thrombolytic therapy. There is eviden...
Use of viscoelastic coagulation testing to monitor low molecular weight heparin administration to healthy horses. To evaluate the utility of thromboelastography (TEG) and Sonoclot analyses to monitor the effects of low molecular weight heparin (LMWH) administration to healthy horses. Methods: Randomized crossover study. Methods: Large animal veterinary teaching hospital. Methods: Six adult mixed breed healthy mares. Methods: LMWH (dalteparin) was administered (50 U/kg subcutaneously) either every 12 or 24 h for 3 consecutive days. Blood samples were collected before LMWH administration and then at selected time points for analysis. Thromboelastography derived R-time (R), K-time (K), angle (ANG), and maxim...
Pharmacodynamics of multi-dose low molecular weight heparin in healthy horses. To compare the pharmacodynamics of once daily and twice daily administration of low molecular weight heparin (LMWH) administration in horses. Methods: Randomized cross over study. Methods: Adult mixed breed healthy mares (n = 6). Methods: LMWH (dalteparin) was administered (50 U/kg subcutaneously) either every 12 or 24 hours for 3 consecutive days. Anti-factor Xa activity was measured before and at select time points after LMWH administration. Packed cell volume (PCV), platelet count, partial thromboplastin time (PTT), and anti-thrombin (AT) activity were monitored throughout the study. Result...
Equine herpesvirus type 1 infection induces procoagulant activity in equine monocytes. The alphaherpesvirus, equine herpesvirus type 1 (EHV-1), is a highly prevalent cause of equine infectious abortion and encephalomyelopathy. These syndromes have been attributed to ischemic necrosis from thrombosis in placental and neural vessels, although the mechanisms underlying thrombosis are unknown. After inhalation, EHV-1 establishes a peripheral blood mononuclear cell-associated viremia, with monocytes being a target of infection. Monocytes are also the main source of tissue factor (TF) in diseased states. Since TF is the primary activator of coagulation, increased monocyte TF expressio...
The effects of hyperglycemia and endotoxemia on coagulation parameters in healthy adult horses. Hyperglycemia and endotoxemia have been associated with coagulation abnormalities in horses. Studies in humans suggest greater disturbances in coagulation with hyperglycemia and concurrent endotoxemia. Objective: To compare coagulation parameters in horses administered with lipopolysaccharide (LPS) with and without concurrent hyperglycemia. Methods: Twelve healthy adult horses. Methods: Hyperglycemia (180-240 mg/dL) was maintained for 6 hours in 6 horses (GLU-LPS) using 140 mg/kg IV bolus of dextrose followed by a 20% dextrose constant rate infusion. A similar volume of saline was administe...
Effects of imidazoline and nonimidazoline alpha-adrenergic agents, including xylazine, medetomidine, yohimbine, tolazoline, and atipamezole, on aggregation of bovine and equine platelets. To investigate effects of various imidazoline and nonimidazoline α-adrenergic agents on aggregation and antiaggregation of bovine and equine platelets. Methods: Blood samples obtained from 8 healthy adult cattle and 16 healthy adult Thoroughbreds. Methods: Aggregation and antiaggregation effects of various imidazoline and nonimidazoline α-adrenergic agents on bovine and equine platelets were determined via a turbidimetric method. Collagen and ADP were used to initiate aggregation. Results: Adrenaline, noradrenaline, or α-adrenoceptor agents alone did not induce changes in aggregation of bov...
Hand-assisted laparoscopic ovariectomy and colpotomy in standing mares. To determine the feasibility of hand-assisted laparoscopic ovariectomy via colpotomy for bilateral ovariectomy in standing mares. Methods: Case series. Methods: Mares (n = 21) aged 2-21 years, weighing 312-582 kg. Methods: After a pilot study in 6 mares, the technique was used in 15 mares. Ovaries were identified and manipulated using 2 laparoscopic portals in the left paralumbar fossa. Transection and hemostasis of the ovarian pedicle was achieved using a LigaSure Atlas™ or chain écraseur. Ovaries were removed through a colpotomy by an assistant. Results: In 19 mares, both ovaries were suc...
Thrombelastographic characterization of coagulation/fibrinolysis in horses: role of carboxyheme and metheme states. Carboxyheme and metheme states modulate hemostasis in humans and other species. Further, carbon monoxide and/or nitric oxide production increase in inflammatory disorders involving the gastrointestinal tract, with associated hypercoagulability or hypocoagulability. In particular, the horse suffers both thrombotic or coagulopathic complications during acute gastrointestinal disease. This investigation characterized the thrombelastographic response to carboxyheme (via CORM-2) or metheme (via phenylhydroxylamine, PHA) states without/with addition of tissue type plasminogen activator. Citrated pla...
Comparison of peritoneal fluid values after laparoscopic cryptorchidectomy using a vessel-sealing device (Ligasure™) versus a ligating loop and removal of the descended testis. To determine the effect of unilateral laparoscopic cryptorchidectomy and removal of the descended testis on peritoneal fluid values, and to compare effect between 2 methods for cryptorchid testis vessel hemostasis. Methods: Randomized clinical study. Methods: Stallions (n = 10) with unilateral abdominal cryptorchid testis. Methods: During standing laparoscopic cryptorchidectomy, blood vessels within the mesorchium of the cryptorchid testis were either sealed and transected with the LigaSure Atlas™ or 2 ligating loops were placed proximal to the testis and the tissue transected with laparosco...
Assessment of acute moderate hyperglycemia on traditional and thromboelastometry coagulation parameters in healthy adult horses. To determine whether experimentally induced acute moderate hyperglycemia is associated with coagulation activation in healthy adult horses. Methods: Prospective experimental study. Methods: University veterinary teaching hospital. Methods: Six healthy adult horses. Methods: Hyperglycemia (10.0-13.3 mmol/L [180-240 mg/dL]) was induced and maintained for 6 hours using a hyperglycemic clamp technique. Blood glucose concentrations were assessed using a point of care (POC) glucometer at 10- and 20-minute intervals throughout the hyperglycemic clamp procedure. Platelet count, fibrinogen concentratio...
Intra and postoperative assessment of re-sterilised Ligasure Atlas for orchidectomies in horses: clinical study. Horses (n=35) underwent orchidectomy in a single institution with a re-sterilised LSA as sole means of haemostasis. During the surgery, the gross quality of the seal, the stickiness of the forceps to the tissues, bleeding/oozing from the stump and the need for a subsequent application in already severed spermatic cord were assessed for haemostasis quality. After surgery, physical parameters (appearance of the mucous membranes, quality of the peripheral pulse, heart rate, respiratory rate, rectal temperature and blood dripping from the incisions), haematology or packed cell volume and total pro...
