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.
Schliewert EC, Hooijberg EH, Goddard A.African horse sickness (AHS), caused by the vector-borne African horse sickness virus (AHSV), is endemic to sub-Saharan Africa and infection results in high mortality in naïve equine populations. Clinical signs include submucosal petechiae and prolonged bleeding post venepuncture indicative of hypocoagulation. Pathological activation of haemostasis may result from tissue factor expression as a result of vascular endothelial damage or dysfunction, the proposed pathologic mechanism in AHS, potentially resulting in disseminated intravascular coagulation (DIC). Objective: To describe haemostatic ...
Tyrnenopoulou P, Flouraki E, Folias L, Loukopoulos E, Starras A, Chalvatzis P, Tsioli V, Mavrogianni VS, Fthenakis GC.The objectives of this work were (i) to evaluate the incidence of complications in male horses after orchiectomy performed in the field, i.e., away from a veterinary hospital, (ii) to describe the post-operative complications that occurred in these animals and (iii) to study the potential predictors for the development of such complications. This study involved 612 animals, on which orchiectomy was performed. The operative part of the study was carried out by one of three experienced veterinary surgeons. Standard pre-operative procedures were followed. Orchiectomy was performed using one of th...
Yeomans A, Hampson R, Razemba T.Special considerations for donkeys undergoing castration compared with horses include the presence of large scrotal vessels, larger testicular artery and vein and the consequential increased risk of post-operative haemorrhage which necessitates spermatic cord ligation. Objective: This retrospective study compares haemorrhagic complication rates between two methods of spermatic cord ligation in donkeys castrated in rural Malawi. Methods: All donkeys presenting to Veterinary Education Malawi / Lilongwe Society for the Protection and Care of Animals rural large animal outreach clinics for castrat...
Vokes JR, Lovett AL, de Kantzow MC, Rogers CW, Wilkins PA, Sykes BW.Viscoelastic monitoring of horse coagulation is increasing due to its advantages over traditional coagulation testing. The use of a point-of-care viscoelastic coagulation monitor (VCM Vet™) has been validated for use in horses using native whole blood (NWB) but has not been assessed using citrated whole blood (CWB), a technique that might have advantages in practicality and precision. Blood was collected from 70 horses, tested in duplicate immediately using NWB (T0), and stored at room temperature as CWB for testing in duplicate at 1 (T1) and 4 (T4) hours after venipuncture for comparison to...
Vernemmen I, Buschmann E, Van Steenkiste G, Demeyere M, Verhaeghe LM, De Somer F, Devreese KMJ, Schauvliege S, Decloedt A, van Loon G.Cardiac catheterizations in horses are mainly performed in the right heart, as access to the left heart traditionally requires an arterial approach. Transseptal puncture (TSP) has been adapted for horses but data on follow-up and closure of the iatrogenic atrial septal defect (iASD) are lacking. Objective: To perform TSP and assess postoperative complications and iASD closure over a minimum of 4 weeks. Methods: Eleven healthy adult horses. Methods: Transseptal puncture was performed under general anesthesia. Serum cardiac troponin I concentrations were measured before and after puncture. Wee...
Miglio A, Falcinelli E, Mezzasoma AM, Busechian S, Rueca F, Gresele P, Antognoni MT.Physical exercise has an activating effect on platelet function that differs between trained and untrained subjects, depending on the type of exercise and training status. In humans, soluble P-selectin (sP-sel) and platelet-derived extracellular vesicles (PEVs) are considered reliable markers of platelet activation during exercise. In untrained humans, they increase after transient physical exercise, whereas long-term training induces a decrease in their resting levels due to an improved ability to adapt to hemodynamic changes. The aim of this study was to assess whether circulating levels of...
Miglio A, Falcinelli E, Cappelli K, Mecocci S, Mezzasoma AM, Antognoni MT, Gresele P.Training has a significant effect on the physiology of blood coagulation in humans and in horses. Several hemostatic changes have been reported after exercise in the horse but data available are inconclusive. The aim of this study was to investigate platelet activation and primary platelet-related hemostasis modifications in young never-trained Thoroughbreds in the first incremental training period in order to improve knowledge on this topic. Twenty-nine clinically healthy, untrained, 2-year-old Thoroughbred racehorses were followed during their incremental 4-month sprint exercise training. Bl...
Bishop RC, Kemper AM, Burges JW, Jandrey KE, Wilkins PA.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. Methods: Prospective observational study. Methods: Two university teaching hospitals. Methods: Healthy adult horses (n = 68). Methods: None. 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, am...
Bonomelli N, Höglund OV, Bonilla AG.To report the use and feasibility of a self-locking resorbable loop device for cryptorchidectomy. Methods: Clinical prospective study. Methods: Twenty horses. Methods: Horses suspected to have an abdominal testicle/s after admission work-up were enrolled. Horses were anesthetized in dorsal recumbency and a standard laparoscopic technique was performed. The looped device was inserted into the abdomen, glided around the testis/cord and tightened. Then, the spermatic cord was transected prior testis removal. Surgical procedure details and remarks, perioperative complications and total surgical ti...
Díaz Yucupicio S, Bishop RC, Fick ME, Austin SM, Barger AM, Stolsworth B, Wilkins PA.Determine the effect of sample holding time and single sample reuse on viscoelastic coagulation parameters when using fresh equine native whole blood. Methods: 8 healthy adult horses from a university teaching herd. Methods: Blood collected by direct jugular venipuncture (18 ga needle, 3 mL syringe) was held at 37 °C for 2, 4, 6, or 8 minutes according to 1 of 2 protocols. Syringes were gently inverted twice, a small amount of blood was expressed, testing cartridges were filled, and placed within the VCM-Vet™ device (Entegrion Inc). Protocol A: samples were processed from a single syringe. ...
Weixler VHM, Kuschnerus K, Romanchenko O, Ovroutski S, Cho MY, Berger F, Sigler M, Sinzobahamvya N, Photiadis J, Murin P.The aim was to report mid-term performance of decellularized equine pericardium used for repair of various congenital heart defects in the pediatric population. Methods: A retrospective review of all patients undergoing patch implantation between 2016 - 2020 was performed. Patch quality, surgical handling, hemostasis and early patch-related complications were studied on all patients. Mid-term performance was observed in patients with ≥12 months follow-up and intact patch at discharge (without reoperation/stent implantation). Results: A total of 201 patients with median age of 2.5 years [inte...
Bishop RC, McCoy AM, Kemper AM, Stewart RM, Wilkins PA.To evaluate the effect of the cyclooxygenase-2-selective NSAID firocoxib, compared to the nonselective NSAID flunixin meglumine on viscoelastic coagulation parameters in healthy horses. 12 healthy adult mixed-breed horses. Following a crossover protocol, horses were administered flunixin meglumine (1.1 mg/kg, IV, q 12 h for 5 days), allowed a 6-month washout period, and then administered firocoxib (0.3 mg/kg, PO, once, then 0.1 mg/kg, PO, q 24 h for 4 days). Omeprazole (1 mg/kg, PO, q 24 h) was administered concurrently with each NSAID. Viscoelastic coagulation profiles and traditional coagula...
Honoré ML, Pihl TH, Busk-Anderson TM, Flintrup LL, Nielsen LN.D-dimer has value as a marker of thrombosis in critically ill horses and can provide additional information about prognosis. However, there are currently no equine species-specific d-dimer assays available, nor has there been any formal investigation of the applicability of human d-dimer assays in horses, so it is unknown, which assay performs best in this species. The aim of this study was therefore to evaluate and compare two human d-dimer assays for their applicability in horses. The study included four groups of horses: clinically healthy horses, horses with gastrointestinal (GI) disease a...
Deng L, Li Z, Tang C, Han Y, Zhang L, Liao Q.Equine pregnancy is currently diagnosed by rectal palpation, ultrasonographic examination, or by measuring changes in hormones in the blood. In the present study, we identified proteins that are differentially expressed in the sera of early pregnant and non-pregnant mares in order to develop a novel method for diagnosing equine pregnancy. Serum samples were obtained from 18 adult mares, pregnancy at day 32 after ovulation (n = 9) and in diestrus (n = 9). Proteomic analysis of the samples was conducted using liquid chromatography-electrospray ionization-tandem mass spectrometry. We iden...
Lovett AL, Gilliam LL, Sykes BW, McFarlane D.Both obesity and metabolic syndrome are associated with hypercoagulability in people, increasing the risk of cardiovascular disease and thromboembolic events. Whether hypercoagulability exists in obese, insulin-dysregulated horses is unknown. Objective: To determine if coagulation profiles differ between healthy horses and those with obesity and insulin dysregulation. Methods: Fifteen healthy horses (CON) and 15 obese, insulin-dysregulated horses (OBID). Individuals were university or client owned. Methods: Case-control study. Obesity was defined as a body condition score (BCS) ≥7.5/9 (modif...
Leclere M, Chevalier Z, Dubuc V, Beauchamp G, Bédard C.The amount of thrombin generated reflects the endogenous thrombin potential (ETP), which depends on the balance of pro- and anticoagulant factors. The calibrated automated thrombogram (CAT) allows for the direct measurement of thrombin generation during the clotting process. Objective: (1) To describe the results of the CAT assay in horses, (2) to establish intra-assay and intra- and interindividual variation of thrombin generation in healthy horses, and (3) to compare in vitro low-molecular-weight heparin (LMWH) sensitivity between healthy and sick horses. The hypothesis for the last objectiv...
Hurcombe SDA, Radcliffe RM, Cook VL, Divers TJ.Hemorrhagic shock in horses may be classified in several ways. Hemorrhage may be considered internal versus external, controlled or uncontrolled, or described based on the severity of hypovolemic shock the patient is experiencing. Regardless of the cause, as the severity of hemorrhage worsens, homeostatic responses are stimulated to ameliorate the systemic and local effects of an oxygen debt. In mild to moderate cases of hemorrhage (<15% blood volume loss), physiological adaptations in the patient may not be clinically apparent. As hemorrhage worsens, often in the uncontrolled situation suc...
Lanier CJ, Taintor JS, Christopherson PW, Spangler EA.Acidemia in sick or injured horses is often due to lactic acid accumulation. Alterations in platelet function and hemostasis are among numerous deleterious effects caused by decreased physiologic pH. Objective: We aimed to evaluate the effect of hyperlactatemia and resultant acidemia on platelet aggregation in equine whole blood using impedance aggregometry. Methods: Platelet aggregation was measured using the Multiplate analyzer in whole blood from 34 healthy horses at baseline and after in vitro addition of lactic acid to adjust the pH. Platelet aggregation of each sample was quantified by t...
Honoré ML, Pihl TH, Nielsen LN.Critically ill horses, such as horses with gastrointestinal (GI) disease, often suffer from hemostatic aberrations. Global hemostatic tests examining the initiation of coagulation, clot strength and fibrinolysis, such as the Calibrated Automated Thrombogram (CAT) and plasma-thromboelastography (TEG) have not been evaluated in horses. This study aimed to evaluate CAT and apply plasma-TEG in horses. Test performance of CAT was evaluated on equine platelet poor plasma with intra- and inter-assay variability (CV) and a heparin dilution curve. To examine clinical performance of both tests, group co...
Hurcombe SD, Roessner HA, Klein CE, Engiles JB, Hopster K.Jejunal vascular ligation is an essential step in performing jejunojejunostomy. Hand sewn ligation is typically used and can increase operative time with long sections of bowel to be removed. Nylon cable ties (NCT) have been used for vascular ligation in horses but are yet to be investigated for application on the mesenteric vasculature of the gastrointestinal tract. Our objective was to evaluate the efficacy and short-term safety of NCT jejunal mesenteric vessel ligation in healthy horses. Eight healthy adult horses underwent midline celiotomy. A segment of jejunal mesentery was identified (...
Hurcombe SD, Klein CE, Roessner HA, Engiles JB, Hopster K.To report the use of nylon cable ties (NCT) for omentectomy in the horse. Methods: Experimental study. Methods: Eight healthy adult horses. Methods: Horses underwent nylon cable tie (NCT) ligation of the greater omentum after ventral midline celiotomy. The time required to complete the omentectomy was recorded. Horses were recovered for 14 days before repeat celiotomy, adhesions assessment, and histological examination of the omentectomy site using a proposed histologic grading scheme. The total time for omentectomy procedure and histologic score was assessed for normality. Data are expresse...
Lemon AV, Goddard A, Hooijberg EH.The accessibility of thromboelastography (TEG) to general practitioners is limited by short sample storage times (30 minutes) and storage temperatures (20-23°C). Objective: We aimed to evaluate the stability of canine and equine citrated blood samples when stored for extended periods of time, both at room temperature (RT) (20-23°C) and refrigerator temperature (FT) (2-7.5°C). Methods: Citrated whole blood samples from healthy dogs and horses (n = 10 for each) were stored for 30 minutes (baseline) at RT before TEG analysis. Baseline values for TEG variables R, K, α, MA, LY30, and LY60 w...
Russell EB, Courtman NF, Santos LL, Tennent-Brown BS.Fibrinogen heterogeneity has been observed in humans and can influence fibrinogen measurements when using the modified Clauss assay. We hypothesized that fibrinogen heterogeneity also exists in horses. Objective: To determine whether fibrinogen heterogeneity exists in horses. Methods: Five clinically healthy horses from the university equine teaching herd. Methods: Presumed fibrinogen was purified from pooled citrated plasma and electrophoresis performed. The purified protein was subjected to Western blotting using sheep antiserum against human fibrinogen, and liquid chromatography-tandem ma...
Miglio A, Falcinelli E, Mezzasoma AM, Cappelli K, Mecocci S, Gresele P, Antognoni MT.Training has a strong effect on the physiology of hematological parameters and blood coagulation, both in humans and in horses. Several blood changes have been reported after exercise in horses but available data differ. We aimed to investigate modifications in complete blood count and some hemostatic parameters induced by the first training period in young untrained Thoroughbred racehorses to detect a possible labile blood coagulability in racehorses. Twenty-nine untrained 2-year-old Thoroughbreds were followed during their incremental 4-month sprint exercise schedule. Blood collection was pe...
Ehrmann C, Engel J, Moritz A, Roscher K.In addition to maintaining hemostasis, platelets have an important role in modulating innate and adaptive immune responses. A low platelet count has been found to be a negative prognostic factor for survival in humans and horses with critical illnesses, such as sepsis or systemic inflammatory response syndrome (SIRS). Decreased platelet aggregation, caused by in vivo activation, has been found in human patients with severe sepsis. In our prospective controlled study, we assessed platelet biology in blood samples from 20 equine SIRS cases and 120 healthy control horses. Platelet variables such ...
Pliszczak-Król A, Gemra M, Kozdrowski R, Zalewski D, Iwaszko A.Recurrent Airway Obstruction (RAO), also called severe asthma or heaves, is a chronic disease in adult horses caused by aeroallergens from straw or hay. Disturbances in hemostasis (intensified coagulation and depressed fibrinolysis) are considered one of the prominent reasons of inflammatory process, injury and dysfunction of the lungs. The aim of the study was to evaluate chosen parameters of hemostasis in horses with active form of RAO. Ten RAO-horses (group R) and ten healthy horses (group C) were exposed to straw and hay allergen challenge. The prothrombin time (PT), activated partial thro...
Pennati A, Apfelbeck T, Brounts S, Galipeau J.Mammalian platelets participate in the immediate tissue injury response by initiating coagulation and further promoting tissue injury mitigation and repair. The latter properties are deployed following platelet release of presynthetized morphogens, cytokines, and growth and chemotactic factors, which launch a tissue regenerative, angiogenic, and anti-inflammatory program. Several blood-derived biologic products, like platelet-rich plasma (PRP) and platelet lysate (PL), are currently on the market to allow proper healing and tissue regeneration. However, not all growth factors are released from...
Giusto G, Gandini M.In equine abdominal surgery, resection and anastomosis of strangulated intestine is a commonly performed procedure. To date, ligatures, vessel sealing devices and the ligate-divide stapler have been described for this use in horses. The objective of this study was to compare the application of haemostatic clips and ligatures to occlude equine mesenteric vessels. Portions of jejunum with ten associated mesenteric vessels were collected from 12 horses at a local abattoir and divided into two groups. Portions of intestine were divided into two sections comprising five vessels each and assigned to...
Satué K, Gardon JC, Muñoz A.The process of fibrin clot formation is a series of complex and well-regulated reactions involving blood vessels, platelets, procoagulant plasma proteins, natural inhibitors, and fibrinolytic enzymes. Vasculitis can be caused by a variety of different agents as bacteria, viruses, protozoal, rickettsial organisms, toxic, drugs, medications, and neoplasms. The most common cause of vasculitis is the purpura hemorrhagica, which is associated with exposure to Streptococcus equi ssp. equi or less commonly, equine influenza. Deficiencies or defects of the hemostatic components may result in bleeding ...
Terzi A, Gallo N, Bettini S, Sibillano T, Altamura D, Madaghiele M, De Caro L, Valli L, Salvatore L, Sannino A, Giannini C.Collagen represents one of the most widely used biomaterial for scaffolds fabrication in tissue engineering as it represents the mechanical support of natural tissues. It also provides physical scaffolding for cells and it influences their attachment, growth, and tissue regeneration. Among all fibrillary collagens, type I is considered one of the gold standard for scaffolds fabrication, thanks to its high biocompatibility, biodegradability, and hemostatic properties. It can be extracted by chemical and enzymatic protocols from several collagen-rich tissues, such as tendon and skin, of differen...
Terzi A, Gallo N, Bettini S, Sibillano T, Altamura D, Madaghiele M, De Caro L, Valli L, Salvatore L, Sannino A, Giannini C.Collagen represents one of the most widely used biomaterial for scaffolds fabrication in tissue engineering as it represents the mechanical support of natural tissues. It also provides physical scaffolding for cells and it influences their attachment, growth, and tissue regeneration. Among all fibrillary collagens, type I is considered one of the gold standard for scaffolds fabrication, thanks to its high biocompatibility, biodegradability, and hemostatic properties. It can be extracted by chemical and enzymatic protocols from several collagen-rich tissues, such as tendon and skin, of differen...
Bonnefoy A, Romijn RA, Vandervoort PA, VAN Rompaey I, Vermylen J, Hoylaerts MF.Binding of von Willebrand factor (VWF) to platelet GPIbalpha and to collagen is attributed to VWF A1 and A3 domains, respectively. Objective: Using VWF, VWF lacking A1 (DeltaA1-VWF) or A3 (DeltaA3-VWF) and VWF with defective A3 (H1786A-VWF), in combination with recombinant A1 (residues 1262-1492) or A3 (residues 1671-1878), fused to glutathione-S-transferase (GST-A1 and GST-A3), we have re-investigated the role of A1 in platelet recruitment to surfaces of collagen. Results: In flow, measurable binding of DeltaA3-VWF occurred to horse tendon, but also to human type III collagen. GST-A1 and GST-...
Kurachi K, Schmer G, Hermodson MA, Teller DC, Davie EW.A comparison of the physical-chemical properties of human, bovine, and horse antithrombin III has been made. These three plasma proteins are strong inhibitors of bovine factor Xa and form a 1:1 molar complex with this coagulation enzyme. Human, bovine, and horse antithrombin III are glycoproteins containing hexose, hexosamine, and neuraminic acid. The total carbohydrate was 9, 12, and 16% for human, bovine, and horse antithrombin III, respectively. These proteins have a similar amino acid composition, although some monor variations were noted. Each antithrombin III is composed of a single poly...
Karges HE, Funk KA, Ronneberger H.Using diagnostics for the determination of clotting factors and fibrinolytic parameters in human plasma, samples from rat, guinea pig, rabbit, cat, dog, sheep, cattle, horse, pig, and monkey were analysed. The human system was employed even for standard curves and controls. Results obtained in this way are relative values in relation to pooled fresh human plasma of healthy donors which is defined to contain 100% of the norm or 1 unit of each factor per 1 ml. Under these conditions, marked differences between the human clotting system and those of different animal species appear. Thus, rabbits ...
Peek SF, Semrad S, McGuirk SM, Riseberg A, Slack JA, Marques F, Coombs D, Lien L, Keuler N, Darien BJ.This prospective study compared survival rates of critically ill and septic foals receiving 1 of 2 different types of commercial equine plasma and analyzed admission variables as possible predictors of survival. Standardized clinical, hematologic, biochemical, and hemostatic admission data were collected and foals received either conventional commercially available hyperimmune equine plasma or equine plasma specifically rich in antiendotoxin antibodies in a double-blinded, coded fashion. Sepsis was defined as true bacteremia or sepsis score >11. Overall survival rate to discharge was 72% (4...
Delgado MA, Monreal L, Armengou L, Ríos J, Segura D.Plasma D-dimer concentration is a useful marker to assess systemic coagulation and fibrinolytic activities in humans, dogs, and horses. Peritoneal fibrinolytic activity increases in horses with colic, especially in horses with endotoxin in the peritoneal fluid. Objective: Peritoneal D-dimer concentration can be used to assess peritoneal fibrinolytic activity in horses with severe gastrointestinal (GI) disorders and altered peritoneal fluid. Methods: Two hundred and twenty-one colic horses and 15 control horses. Methods: Prospective observational clinical study. Blood and peritoneal fluid were ...
Miglio A, Falcinelli E, Mezzasoma AM, Cappelli K, Mecocci S, Gresele P, Antognoni MT.Training has a strong effect on the physiology of hematological parameters and blood coagulation, both in humans and in horses. Several blood changes have been reported after exercise in horses but available data differ. We aimed to investigate modifications in complete blood count and some hemostatic parameters induced by the first training period in young untrained Thoroughbred racehorses to detect a possible labile blood coagulability in racehorses. Twenty-nine untrained 2-year-old Thoroughbreds were followed during their incremental 4-month sprint exercise schedule. Blood collection was pe...
Andreassen SM, Vinther AML, Nielsen SS, Andersen PH, Tnibar A, Kristensen AT, Jacobsen S.Septic arthritis is a common and potentially devastating disease characterized by severe intra-articular (IA) inflammation and fibrin deposition. Research into equine joint pathologies has focused on inflammation, but recent research in humans suggests that both haemostatic and inflammatory pathways are activated in the joint compartment in arthritic conditions. The aim of this study was to characterize the IA haemostatic and inflammatory responses in horses with experimental lipopolysaccharide (LPS)-induced joint inflammation. Inflammation was induced by IA injection of LPS into one antebrach...
Cesarini C, Monreal L, Armengou L, Delgado MÁ, Ríos J, Jose-Cunilleras E.Coagulopathies detected in horses with gastrointestinal problems seem to be associated with poor outcome. Plasma D-Dimer concentration is a sensitive test for assessing coagulopathies. Objective: Plasma D-Dimer concentration tested on admission is related to diagnosis and outcome in horses with colic. Methods: Four hundred and ninety three horses referred for evaluation of abdominal pain. Methods: Prospective observational clinical study. Horses were grouped according to diagnosis (medical and surgical intestinal obstructions, ischemic disorders with and without intestinal resection, enteritis...
Monreal L, Anglés A, Espada Y, Monasterio J, Monreal M.Changes in haemostasis in horses with colic were assessed by using specific and sensitive markers of coagulation and fibrinolysis activity. Blood samples from 41 horses with severe colic and from 30 healthy control horses were tested. Diagnosis of DIC was based on the findings of at least 3 of 6 abnormalities: thrombocytopenia, prolonged clotting times (PT and APTT), increased polyclonal FDPs, decreased fibrinogen and decreased AT-III activity. Plasma thrombin-antithrombin III complexes (TAT), monoclonal fibrin degradation products fragment D (D-dimer) and monoclonal fibrinogen degradation pro...
Stokol T, Yeo WM, Burnett D, DeAngelis N, Huang T, Osterrieder N, Catalfamo J.Equid herpesvirus type 1 (EHV-1) causes outbreaks of abortion and neurological disease in horses. One of the main causes of these clinical syndromes is thrombosis in placental and spinal cord vessels, however the mechanism for thrombus formation is unknown. Platelets form part of the thrombus and amplify and propagate thrombin generation. Here, we tested the hypothesis that EHV-1 activates platelets. We found that two EHV-1 strains, RacL11 and Ab4 at 0.5 or higher plaque forming unit/cell, activate platelets within 10 minutes, causing α-granule secretion (surface P-selectin expression) and pl...
Yeo WM, Osterrieder N, Stokol T.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...
Hand R, Rakestraw P, Taylor T.To evaluate a vessel-sealing instrument (LigaSure) as a method for hemostasis of the ovarian vasculature. Methods: Prospective study. Methods: Thirteen mares (8 experimental, 5 patients), aged 2 to 20 years and weighing 405 to 500 kg. Methods: Thirteen mares had standing bilateral laparoscopic ovariectomy using a vessel-sealing device (LigaSure) to provide hemostasis. Eight reproductively normal experimental mares were divided into 2 groups: 1 group was re-examined laparoscopically 72 hours and the other group 10 days after the initial standing laparoscopic ovariectomy. The vessel-sealing devi...
Dias DP, de Lacerda Neto JC.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...
Röcken M, Mosel G, Seyrek-Intas K, Seyrek-Intas D, Litzke F, Verver J, Rijkenhuizen AB.To evaluate surgical techniques, perioperative complications and outcome of laparoscopic surgery for unilateral and bilateral ovariectomy in mares. Methods: Retrospective multicenter case series. Methods: Mares (n = 157). Methods: Indications for surgery were neutering, fertility problems, elimination of hormone-related abnormal behavior, ovarian tumors as well as nonregressive ovarian hematomas or cysts. Ovariectomy (n = 206) were performed by a standard laparoscopic procedure in 157 standing sedated mares. Dissection and hemostasis were achieved by using either (1) a linear stapling device, ...
Jones PA, Tomasic M, Gentry PA.To evaluate the oncotic, hemodilutional, and hemostatic effects of IV infusions of a large volume of isotonic saline solution and 2 doses of 6% hydroxyethyl starch (HES) in clinically normal ponies. Methods: 12 adult ponies. Methods: Ponies were assigned to 3 treatment groups and received the following IV infusions: 80 ml of 0.9% sodium chloride/kg; 10 ml of 6% HES (in 0.9% sodium chloride)/kg; or 20 ml of 6% HES (in 0.9% sodium chloride)/kg. Blood samples were collected for determination of colloid oncotic pressure (COP), PCV, plasma total protein concentration, platelet count, von Willebrand...
Mendez-Angulo JL, Mudge MC, Vilar-Saavedra P, Stingle N, Couto CG.To evaluate the use of citrated recalcified (nonactivated) thromboelastography (TEG) in healthy horses and horses with colitis and suspected coagulopathies. Methods: Prospective, observational study conducted between October 2007 and June 2009. Methods: Veterinary Teaching Hospital. Methods: Forty-five healthy adult horses and 12 sick adult horses with colitis and prolonged prothrombin time (PT) or activated partial thromboplastin time (aPTT). Methods: None. Results: Whole blood was collected on admission. Coagulation profile (PT, aPTT, platelet count, and fibrinogen concentration) and citrate...
Hanrath M, Rodgerson DH.To describe a technique for laparoscopic cryptorchidectomy in standing horses using electrosurgical instrumentation. Methods: Retrospective clinical study. Methods: Ten horses, 1 to 7 years of age, with unilaterally or bilaterally retained testes. Methods: Food was withheld for a minimum of 12 to 24 hours. Horses were sedated using xylazine hydrochloride (0.5 to 1 mg/kg) and butorphanol tartrate (0.02 mg/kg) or detomidine hydrochloride (0.02 to 0.03 mg/kg) and restrained in standing stocks. Three portal sites in the paralumbar fossae were locally desensitized using 2% mepivacaine. After trocar...
McMichael M, Goggs R, Smith S, Wagg C, Warman S, Wiinberg B.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...
Moore BR, Hinchcliff KW.Heparin is used clinically in horses to treat hemostatic abnormalities associated with severe gastrointestinal disease, septicemia, and endotoxemia. The primary anticoagulant effect of heparin is through the suppression of thrombin-dependent amplification of the coagulation cascade, and inhibition of thrombin-mediated conversion of fibrinogen to fibrin. Heparin may be of benefit in preventing the complications associated with hypercoagulable states such as jugular vein thrombosis, laminitis, and organ failure. Heparin may also be beneficial in the prevention of intraabdominal adhesions after g...
Barton MH, Morris DD, Norton N, Prasse KW.Thirteen coagulation tests evaluating hemostatic and fibrinolytic indices and serum cytokine and plasma endotoxin concentrations were obtained in 34 foals with a positive sepsis score (septic group) and 46 age-matched healthy foals. Compared to healthy foals, the prothrombin, activated partial thromboplastin, and whole blood recalcification times were significantly longer in septic foals. The fibrinogen and fibrin degradation products concentrations, percent plasminogen, alpha-2 antiplasmin, and plasminogen activator inhibitor activities, and tumor necrosis factor and interleukin-6 activities ...
Epstein KL.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.
Epstein KL, Brainard BM, Giguere S, Vrono Z, Moore JN.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...
Cotovio M, Monreal L, Armengou L, Prada J, Almeida JM, Segura D.Septicemia in human neonates frequently is complicated by activation of the coagulation system, disseminated intravascular coagulation (DIC) and multiple organ failure syndrome, which may contribute to high mortality. In adult horses with DIC, the lung has been the organ most frequently affected by fibrin deposits. In addition, in vivo studies suggest that hemostatic mechanisms may be immature in foals < 1-day old. Objective: Newborn foals with severe septicemia have fibrin deposits in their tissues independently of their age, and these fibrin deposits are associated with organ failure. Met...
Divers TJ.Organ thrombosis and laminitis are life-threatening complications in horses with acute gastrointestinal disease, especially those diseases that cause disruption of the protective mucosal barrier. Prevention of these complications should be a high priority when treating horses with gastrointestinal diseases because even with proper and intensive treatments, laminitis or organ thrombosis may not be curative. Preventative therapy should include expedient and appropriate treatment of the primary disease, normalization of tissue perfusion and oxygenation, and inhibition of gut-derived toxins or the...
Epstein KL, Bergren A, Giguère S, Brainard BM.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 ...
Welch RD, Watkins JP, Taylor TS, Cohen ND, Carter GK.Disseminated intravascular coagulation (DIC) secondary to colic was diagnosed in 23 horses. Each horse was categorized retrospectively as to the cause of the colic based on surgical and/or necropsy findings: group 1 consisted of 14 horses with compromised intestine that required resection and anastomosis; group 2 consisted of 3 horses with nonstrangulating intestinal displacement and/or impactions; and group 3 consisted of 6 horses with colic associated with enteritis and/or colitis. Horses were considered to be affected with DIC if at least three of five hemostatic parameters were significant...
Dallap Schaer BL, Epstein K.To review the hemostasis literature relevant to development of coagulopathy in the critically ill equine patient. Methods: Original scientific and review articles. Results: Inflammation plays a critical role in the activation and amplification of clot formation, as well as the impairment of physiologic anticoagulant mechanisms, and fibrinolysis. Earlier identification of coagulopathy in patients at risk and restoration of physiologic hemostasis may result in better outcome. Development of scoring systems based on information other than coagulation markers alone may better identify patients wit...
