Anti-thrombotic therapy in horses involves the use of medications or interventions to prevent or treat thrombosis, which is the formation of blood clots within blood vessels. Thrombosis can lead to significant health issues in horses, including impaired circulation and tissue damage. Common anti-thrombotic agents used in equine medicine include anticoagulants like heparin and antiplatelet drugs such as aspirin. These therapies aim to reduce the risk of clot formation by interfering with various pathways in the blood coagulation process. Monitoring and managing the balance between preventing thrombosis and avoiding excessive bleeding is a critical aspect of treatment. This page compiles peer-reviewed research studies and scholarly articles that explore the mechanisms, efficacy, and safety of anti-thrombotic therapies in equine patients.
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...
Paulussen E, Decloedt A, Vera L, Lefere L, van Loon G.Venous stenosis, a possible cause of jugular dilatation and congestion, is well known in human medicine but has poorly been described in horses. Objective: To report unilateral jugular vein stenosis as a cause of jugular vein dilatation in horses and describe treatment by percutaneous transluminal angioplasty (PTA). Methods: Case report. Methods: Details of horses diagnosed with unilateral jugular stenosis were retrieved from medical records. Results: Five horses were presented with a non-painful, unilateral dilatation of the jugular vein of which two horses showed headshaking during exercise....
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...
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 ...
Nomura M, Mizobe F, Kato T, Kuroda T, Urayama S, Muranaka M.Although severe blood coagulopathy in horses with acute colitis causes multiple organ failure, which may be fatal, few studies have focused on the correlation between the fluctuations of coagulation parameters and severity of colitis. In this study, we evaluated the fluctuations of coagulation parameters in 14 Thoroughbred racehorses with acute colitis for 5 days from the day of hospitalization and compared them between 5 survivors and 9 non-survivors. Noteworthy features in the non-survivors were that antithrombin activity and fibrin degradation products continuously decreased and increased, ...
Hernandez D, Yeo WM, Brooks MB, Ness SL, Divers TJ, Stokol T.OBJECTIVE To evaluate the effects of treatment of horses with standard platelet inhibitors on ex vivo inhibition of platelet activation by equine herpesvirus type I (EHV-I). ANIMALS II healthy adult horses. PROCEDURES In a double-blinded, placebo-controlled crossover study, horses were treated orally for 5 days with theophylline (5 mg/kg, q 12 h), pentoxifylline (10 mg/kg, q 12 h), clopidogrel bisulfate (4 mg/kg, q 24 h), acetylsalicylic acid (20 mg/kg, q 24 h), or placebo. Horses received all treatments, each separated by a 3-week washout period. Platelet-rich plasma was prepared from citrate...
Rodríguez-Pozo ML, Armengou L, Monreal L, Viu J, Cesarini C, Jose-Cunilleras E.To assess whether an oral direct factor Xa inhibitor (DiXaI) anticoagulant drug used at the low end of the recommended dose in people achieves presumed prophylactic plasma concentrations and does not induce bleeding in horses. Methods: Experimental study. Methods: Field study. Methods: Ten healthy adult horses. Methods: A DiXaI was administered at a dose of 0.125 mg/kg every 24 h orally for 4 days. Following a wash-out period of 2 weeks, 8 of 10 horses received daily subcutaneous doses of a low molecular weight heparin (dalteparin) for 4 consecutive days at 50 IU/kg. In both trials, antifactor...
Navas de Solís C, Reef VB, Slack J, Jose-Cunilleras E.To evaluate horses with atrial fibrillation for hypercoagulability; plasma D-dimer concentrations, as a marker of a procoagulant state; and a relationship between coagulation profile results and duration of atrial fibrillation or presence of structural heart disease. Methods: Case-control study. Methods: Plasma samples from 42 horses (25 with atrial fibrillation and 17 without cardiovascular or systemic disease [control group]). Methods: Results of hematologic tests (ie, plasma fibrinogen and D-dimer concentrations, prothrombin and activated partial thromboplastin times, and antithrombin activ...
Leclere M, Bédard C, Cortes-Dubly ML, Lavoie JP.As inflammation and coagulation are intertwined processes, the efficiency of blood coagulation of heaves-affected horses and controls were compared in an observational case-control study, using thrombelastography. In experiment 1 (Exacerbation, six heaves, five controls), horses were housed indoors and fed hay. Thrombelastography, functional fibrinogen, platelet count, hematology, and antithrombin were measured. In experiment 2 (Remission, eight heaves, 11 controls), horses were housed in a low-dust environment for at least a month when thrombelastography was performed. Heaves-affected horses ...
Whelchel DD, Tennent-Brown BS, Giguère S, Epstein KL.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...
Dunkel B, Chan DL, Boston R, Monreal L.Coagulopathies are common in horses with ischemic or inflammatory gastrointestinal (GI) disturbances. There is indirect evidence suggesting that early stages of these diseases are characterized by hypercoagulability (HC). Objective: HC, assessed via thromboelastography (TEG), is common in horses with ischemic or inflammatory GI diseases. The degree of HC is correlated with nonsurvival and thrombotic complications. Methods: Thirty client-owned horses with ischemic or inflammatory GI disease, 30 client-owned horses with nonischemic or inflammatory GI disease, and 30 healthy horses (control group...
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...
Dallap Schaer BL, Bentz AI, Boston RC, Palmer JE, Wilkins PA.To determine if changes in viscoelastic variables are associated with abnormalities observed in the standard coagulation profile and patient outcome in foals with suspected septicemia. Methods: Prospective clinical trial during 2003 and 2004 foal season. Methods: Neonatal intensive care unit at a veterinary teaching hospital. Methods: Thirty critically ill foals <72-hour-old admitted sequentially meeting criteria for systemic inflammatory response associated with infection. Methods: Hemostatic evaluation, using standard coagulation testing and viscoelastic analysis, was performed at admissi...
Epstein KL, Brainard BM, Lopes MA, Barton MH, Moore JN.To develop a standardized technique for thrombelastography (TEG) analysis in healthy adult horses, with and without the ex vivo addition of tissue factor (TF) as an activator. To determine reference intervals for TEG parameters in the horse, and to determine if traditional coagulation tests correlate with TEG. Methods: Prospective, observational. Methods: Veterinary teaching hospital. Methods: Twenty-six healthy adult horses. Methods: None. Results: Thrombelastography with (TF-TEG) and without (TEG) the addition of TF performed by 4 operators. Coagulation profiles (prothrombin time, activated ...
Wilson EM, Holcombe SJ, Lamar A, Hauptman JG, Brooks MB.The extent of preservation of clotting factors and incidence of transfusion reactions to noncommercial equine plasma is not documented. Objective: Equine frozen plasma would retain its coagulation factor activity within the reference range and the incidence of transfusion reactions would be low. Methods: Ten plasma donor horses. Fifty clinically ill hospitalized horses receiving plasma were reviewed to determine the incidence of reactions. Methods: In vitro study and retrospective case review. Plasma was prepared by gravity sedimentation from whole blood refrigerated for 48 hours. The activiti...
Trachsel D, Cohausz O, Scharf G, Wehrli Eser M.A 14-year old Swiss warmblood gelding was presented to the equine hospital of the University of Zurich because of therapy-resistant fever. An intermittent lameness suggested the presence of an intravascular aorto-iliac thrombus which was confirmed sonographically. Subsequently, treatment was initiated with Heparin s.c. and continued for 7 months with Phenprocoumon (Marcoumar). The dosage was monitored and adjusted according to the prothrombin time, which was initially measured every week, and later maximally biweekly. The lameness improved and the regression of the thrombus could be followed s...
Armengou L, Monreal L, Tarancón I, Navarro M, Ríos J, Segura D.Septicemia is associated with a systemic inflammatory response, hemostatic activation, and disseminated intravascular coagulopathy (DIC). Objective: Increased plasma d-dimer concentration occurs in septic neonates and can reliably detect sepsis or DIC, and predict death in ill neonatal foals. Methods: 40 septic, 41 nonseptic hospitalized foals, and 22 healthy neonates. Methods: Prospective observational clinical study. Blood samples were collected on admission, at 24-48 hours after admission, and at the time of discharge or euthanasia. Plasma d-dimer concentration, clotting times, antithrombin...
Estepa JC, Lopez I, Mayer-Valor R, Rodriguez M, Aguilera-Tejero E.The aim of this study was to evaluate the influence of two commonly used anticoagulants (K3EDTA and lithium heparin) on refractometric and spectrophotometric measurement of total protein (TP) concentration in equine peritoneal fluid samples. The influence of a commercial solution of K3EDTA, a solution of K3EDTA in distilled water and lithium heparin on the refractometric and spectrophotometric (biuret) quantification of TP content in peritoneal fluid samples was assessed. Total protein concentration measured by refractometry was consistently overestimated in samples with commercial K3EDTA. The...
Heidmann P, Tornquist SJ, Qu A, Cebra CK.To determine whether epsilon-aminocaproic acid (EACA) administered IV affects hemostasis and fibrinolysis in clinically normal horses and ponies. Methods: 20 clinically normal adult horses and ponies. Methods: Blood samples were collected 24 hours before (baseline) and 1 and 5 hours after i.v. administration of a low dose (30 mg/kg) or high dose (100 mg/kg) of EACA. Platelet count, fibrinogen concentration, prothrombin time, partial thromboplastin time (PTT), D-dimer concentration, alpha2-antiplasmin activity, and thrombin-antithrombin complex concentration were measured. Values at 1 and 5 hou...
Zbanyszek M, Procajło A, Stopyra A, Sobiech P, Rajski K.Colic in horses very often induces changes in the coagulation system causing the development of disseminated intravascular clotting. It is promoted by blood concentration and an increase in exposition of coagulation activators with a simultaneous decrease in coagulation inhibitors activity, mainly antithrombin III. Progressing blood platelets aggregation supports production of microthromboses and plugging capillary vessels. The progression of this processes causes complications in basic disease and becomes the reason for therapeutic failure. Determination of coagulation system indexes such as ...
Feige K, Dennler M, Kästner SB, Wunderli-Allenspach H, Demuth D, Huber A.Recombinant (r)-hirudin is a specific inhibitor of thrombin that is independent of the activity of antithrombin. Objective: To evaluate pharmacokinetic properties and coagulatory changes of r-hirudin in healthy horses. Methods: Two clinically healthy horses received a single i.v. bolus of 0.4 mg/kg bwt r-hirudin and 6 clinically healthy horses received the same dose subcutaneously (subcut.) q. 12 h for 3 days. Coagulation times and r-hirudin plasma concentration were determined over 720 mins and 3 days after i.v. and subcut. administration, respectively. Results: In all horses, treatment with ...
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...
Feige K, Kästner SB, Dempfle CE, Balestra E.Activation of coagulation can be frequently found in horses with colic. However, it has also been demonstrated as a sequela of surgical trauma alone in humans. The purpose of the present study was to determine changes in coagulation and fibrinolysis in horses that underwent colic surgery and to evaluate whether these changes were secondary to the colic or the surgery and wound healing. Thirty horses that underwent colic surgery with uncomplicated recovery were included. Ten horses with a Forssell's procedure served as control group with a standardized surgical trauma. Besides daily physical ex...
Dolente BA, Wilkins PA, Boston RC.To detect subclinical disseminated intravascular coagulation (DIC) in horses with colitis and to determine any association between the diagnosis of subclinical DIC and outcome or occurrence of complications in horses with colitis. Methods: Prospective study. Methods: 37 horses admitted to a veterinary teaching hospital for treatment of acute colitis. Methods: Coagulation profiles were obtained on each horse 0, 24, and 48 hours after admission. Six tests were performed: platelet count, plasma fibrinogen concentration, prothrombin time, activated partial thromboplastin time, antithrombin activit...
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...
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 ...
Gentry PA, Zareie M, Liptrap RM.The amounts of total protein, albumin, fibronectin, alpha 2-macroglobulin (alpha 2-M), immunoglobulin G, ceruloplasmin and antithrombin were determined in fluids collected from 53 preovulatory equine follicles and compared with the contents of estradiol-17 beta, progesterone and androstenedione, with follicle size and the amounts of the equivalent proteins in normal equine plasma. The concentration of fibronectin and the fibronectin/albumin ratios increased significantly with follicle size and with follicular estradiol levels. The alpha 2-M levels and alpha 2-M/albumin ratios correlated with f...
Weiss DJ, Monreal L, Angles AM, Monasterio J.Carbohydrate-induced laminitis has been associated with decreased platelet survival, decreased blood flow to the hoof wall and with the deposition of platelets and microthrombi within venules in the dermal laminae. To evaluate further the systemic prothrombotic events occurring in the prodromal stages of laminitis, plasma samples from control and laminitis-affected ponies and horses were tested for the presence of thrombin-antithrombin (TAT) complexes and fibrin fragment D (D-dimer). No statistically significant differences between the control and laminitis-affected animals were observed for e...
Topper MJ, Prasse KW, Morris MJ, Duncan A, Crowe NA.To adapt and characterize a human ELISA kit to quantify thrombin-antithrombin III (TAT) complexes in horses, and to evaluate TAT as a marker for hypercoagulation in horses. Methods: 29 clinically normal horses used as controls, and 4 ill horses used to evaluate assay for known causes of hypercoagulation. Methods: A commercially available human sandwich-type ELISA kit with 2 antibodies against human thrombin and antithrombin III that bind selectively to their corresponding TAT antigenic sites was used. Equine TAT standards were made from purified equine thrombin and antithrombin III. Proteins d...
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 ...
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...
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 ...
Johnstone IB, Crane S.The incidence and nature of coagulation abnormalities in horses presented with colic and the possible prognostic value of these abnormalities was investigated. A coagulogram was performed on each of 24 adult Thoroughbred or Standardbred horses. A coagulogram consisted of measurements of eight parameters; platelet count, plasma fibrinogen, plasma antithrombin III (AT), partial thromboplastin time (PTT), prothrombin time (PT), thrombin clotting time (TCT), soluble fibrin monomer (SFM) and fibrin-fibrinogen degradation products (FDP). Retrospective determination of the cause of the colic and outc...
Armengou L, Monreal L, Tarancón I, Navarro M, Ríos J, Segura D.Septicemia is associated with a systemic inflammatory response, hemostatic activation, and disseminated intravascular coagulopathy (DIC). Objective: Increased plasma d-dimer concentration occurs in septic neonates and can reliably detect sepsis or DIC, and predict death in ill neonatal foals. Methods: 40 septic, 41 nonseptic hospitalized foals, and 22 healthy neonates. Methods: Prospective observational clinical study. Blood samples were collected on admission, at 24-48 hours after admission, and at the time of discharge or euthanasia. Plasma d-dimer concentration, clotting times, antithrombin...
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...
Prasse KW, Topper MJ, Moore JN, Welles EG.Eight tests of hemostasis were measured in 233 horses with colic. Blood samples were obtained at admission and for 4 consecutive days of hospitalization. Data were analyzed retrospectively by outcome, by broad-category diagnosis group, by small intestinal disorder, and by smaller categories for comparing specific diseases. Nonsurviving horses and horses with the most severe forms of intestinal ischemia had changes interpreted as hypercoagulative, the intensity of which was increased on the first and second mornings (sample times 2 and 3) after admission, when most significant differences for r...
Navas de Solís C, Reef VB, Slack J, Jose-Cunilleras E.To evaluate horses with atrial fibrillation for hypercoagulability; plasma D-dimer concentrations, as a marker of a procoagulant state; and a relationship between coagulation profile results and duration of atrial fibrillation or presence of structural heart disease. Methods: Case-control study. Methods: Plasma samples from 42 horses (25 with atrial fibrillation and 17 without cardiovascular or systemic disease [control group]). Methods: Results of hematologic tests (ie, plasma fibrinogen and D-dimer concentrations, prothrombin and activated partial thromboplastin times, and antithrombin activ...
Leclere M, Bédard C, Cortes-Dubly ML, Lavoie JP.As inflammation and coagulation are intertwined processes, the efficiency of blood coagulation of heaves-affected horses and controls were compared in an observational case-control study, using thrombelastography. In experiment 1 (Exacerbation, six heaves, five controls), horses were housed indoors and fed hay. Thrombelastography, functional fibrinogen, platelet count, hematology, and antithrombin were measured. In experiment 2 (Remission, eight heaves, 11 controls), horses were housed in a low-dust environment for at least a month when thrombelastography was performed. Heaves-affected horses ...
Cambridge H, Lees P, Hooke RE, Russell CS.The antithrombotic effects of aspirin at two dose rates (4 mg/kg and 11 mg/kg bodyweight [bwt] were evaluated in normal, healthy ponies by measuring template bleeding time. Inhibition of platelet aggregation in response to adenosine diphosphate (ADP) and collagen was evaluated and cyclo-oxygenase activity was monitored by radioimmunoassay of thromboxane B2 (TXB2), the stable metabolite of thromboxane A2 (TXA2). TXB2 was measured in serum and platelet rich plasma. Bleeding time was prolonged significantly until 48 h after treatment at 12 mg/kg bwt and until 4 h at the lower dose rate. Synthesis...
Gerhards H.Low dose calcium heparin was administered subcutaneously at 12 hourly intervals to six healthy horses at an initial dose of 150 iu of heparin/kg bodyweight (bwt) and at a maintenance dose of 120 iu/kg bwt. All injections were given at 0900 and 2100 h. Blood samples for monitoring plasma heparin concentrations were obtained prior to, at 2 hourly intervals for 84 h (treatment period), and at Hours 24, 32, 48 and 96 of the control period. Blood samples for monitoring red blood cell (RBC) mass, plasma antithrombin III activity (AT III), activated partial thromboplastin time (APTT), and thrombin ti...
Epstein KL, Brainard BM, Lopes MA, Barton MH, Moore JN.To develop a standardized technique for thrombelastography (TEG) analysis in healthy adult horses, with and without the ex vivo addition of tissue factor (TF) as an activator. To determine reference intervals for TEG parameters in the horse, and to determine if traditional coagulation tests correlate with TEG. Methods: Prospective, observational. Methods: Veterinary teaching hospital. Methods: Twenty-six healthy adult horses. Methods: None. Results: Thrombelastography with (TF-TEG) and without (TEG) the addition of TF performed by 4 operators. Coagulation profiles (prothrombin time, activated ...
Wilson EM, Holcombe SJ, Lamar A, Hauptman JG, Brooks MB.The extent of preservation of clotting factors and incidence of transfusion reactions to noncommercial equine plasma is not documented. Objective: Equine frozen plasma would retain its coagulation factor activity within the reference range and the incidence of transfusion reactions would be low. Methods: Ten plasma donor horses. Fifty clinically ill hospitalized horses receiving plasma were reviewed to determine the incidence of reactions. Methods: In vitro study and retrospective case review. Plasma was prepared by gravity sedimentation from whole blood refrigerated for 48 hours. The activiti...
Baxter GM.Laminitis is an inflammation of the sensitive laminae along the dorsal aspect of the digit and is considered to be a secondary complication of several predisposing or primary factors. Affected horses are usually very lame, have increased digital pulses, are painful to hoof testers along the toe of the foot, and have evidence of downward rotation or distal displacement of the distal phalanx present on radiographs. Treatments for acute laminitis include anti-inflammatory drugs, anti-endotoxin therapy, vasodilators, antithrombotic therapy, corrective trimming and shoeing, and surgical procedures....
Barton MH, Morris DD, Crowe N, Collatos C, Prasse KW.Hemostatic indices were determined in 45 healthy light breed foals, from birth to 1 month of age, and in 20 healthy adult (> 2 years of age) light breed horses. Blood samples were obtained from each foal at 4 ages: 1) < 24 hours, 2) 4-7 days, 3) 10-14 days, and 4) 25-30 days. The following hemostatic indices were determined: platelet count; prothrombin and activated partial thromboplastin times; activity concentrations of protein C, antithrombin III, plasminogen, alpha-2 antiplasmin, tissue plasminogen activator, and plasminogen activator inhibitor-1; plasma protein C antigen and fibrino...
Parry BW.Clinical pathology is a valuable adjunct to physical examination of cases of colic. The present review considers evaluation of cases of colic for three main purposes: (1) making a prognosis, (2) deciding whether to operate, and (3) making a diagnosis. Blood tests noted to be useful for prognostication were hematocrit, lactate and urea nitrogen concentrations, pH, anion gap, fibrin/fibrinogen degradation products, antithrombin III activity, prothrombin time, and thrombin time. Horses with a poor prognosis often have relative polycythemia, marked lactic acidosis, high anion gap, azotemia, and co...
Dunkel B, Chan DL, Boston R, Monreal L.Coagulopathies are common in horses with ischemic or inflammatory gastrointestinal (GI) disturbances. There is indirect evidence suggesting that early stages of these diseases are characterized by hypercoagulability (HC). Objective: HC, assessed via thromboelastography (TEG), is common in horses with ischemic or inflammatory GI diseases. The degree of HC is correlated with nonsurvival and thrombotic complications. Methods: Thirty client-owned horses with ischemic or inflammatory GI disease, 30 client-owned horses with nonischemic or inflammatory GI disease, and 30 healthy horses (control group...
Feige K, Kästner SB, Dempfle CE, Balestra E.Activation of coagulation can be frequently found in horses with colic. However, it has also been demonstrated as a sequela of surgical trauma alone in humans. The purpose of the present study was to determine changes in coagulation and fibrinolysis in horses that underwent colic surgery and to evaluate whether these changes were secondary to the colic or the surgery and wound healing. Thirty horses that underwent colic surgery with uncomplicated recovery were included. Ten horses with a Forssell's procedure served as control group with a standardized surgical trauma. Besides daily physical ex...
Scott EA, Byars TD, Lamar AM.The hematologic and clinical effects of anticoagulation with warfarin were documented in 4 horses. All of the animals had thrombophlebitis (external jugular vein). Measures of coagulation were monitored, with a prothrombin time of 1.5 to 2.5 x base-line value being used as the effective range of anticoagulation. Recanalization was achieved in 2 of 4 cases. Hemorrhage, both subcutaneous and through a surgical incision, was a complication. Vitamin K1, an antidote to warfarin toxicosis, was administered intravenously to reverse anticoagulation and to control hemorrhage.
Dallap Schaer BL, Bentz AI, Boston RC, Palmer JE, Wilkins PA.To determine if changes in viscoelastic variables are associated with abnormalities observed in the standard coagulation profile and patient outcome in foals with suspected septicemia. Methods: Prospective clinical trial during 2003 and 2004 foal season. Methods: Neonatal intensive care unit at a veterinary teaching hospital. Methods: Thirty critically ill foals <72-hour-old admitted sequentially meeting criteria for systemic inflammatory response associated with infection. Methods: Hemostatic evaluation, using standard coagulation testing and viscoelastic analysis, was performed at admissi...
Gentry PA, Zareie M, Liptrap RM.The amounts of total protein, albumin, fibronectin, alpha 2-macroglobulin (alpha 2-M), immunoglobulin G, ceruloplasmin and antithrombin were determined in fluids collected from 53 preovulatory equine follicles and compared with the contents of estradiol-17 beta, progesterone and androstenedione, with follicle size and the amounts of the equivalent proteins in normal equine plasma. The concentration of fibronectin and the fibronectin/albumin ratios increased significantly with follicle size and with follicular estradiol levels. The alpha 2-M levels and alpha 2-M/albumin ratios correlated with f...
Prasse KW, Allen D, Moore JN, Duncan A.The balance of coagulation and fibrinolysis was studied in 15 horses during the prodromal stages of acute laminitis induced by carbohydrate overload. Progression of the disease was stopped 12 to 24 hours before the expected onset of lameness in trial 1 (8 horses) and at the onset of lameness in trial 2 (7 horses). The end points in each trial were identified by specific changes in blood pressures (trial 1) and by changes in pulse, rectal temperature, and arterial pressure (trial 2) that were anticipated on the basis of original description of the experimental model. Blood samples for hemostasi...
Rodríguez-Pozo ML, Armengou L, Monreal L, Viu J, Cesarini C, Jose-Cunilleras E.To assess whether an oral direct factor Xa inhibitor (DiXaI) anticoagulant drug used at the low end of the recommended dose in people achieves presumed prophylactic plasma concentrations and does not induce bleeding in horses. Methods: Experimental study. Methods: Field study. Methods: Ten healthy adult horses. Methods: A DiXaI was administered at a dose of 0.125 mg/kg every 24 h orally for 4 days. Following a wash-out period of 2 weeks, 8 of 10 horses received daily subcutaneous doses of a low molecular weight heparin (dalteparin) for 4 consecutive days at 50 IU/kg. In both trials, antifactor...
Gerhards H, Eberhardt C.Different doses of heparin were given to equids SC to establish 0.05 to 0.20 U of heparin/ml of plasma. Plasma heparin values and antithrombin III activities were assayed, using chromogenic substrate methods. Activated partial thromboplastin and thrombin times were determined, using conventional coagulation assays. Tests were run every hour (or every 2 hours for antithrombin III) for 12 hours from 5 groups of 5 equids each after single injection of 40, 60, 80, 100, or 125 U of calcium heparin/kg of body weight and from 11 equids after injection of 150 U of calcium heparin/kg. The smaller dose ...
Whelchel DD, Tennent-Brown BS, Giguère S, Epstein KL.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...
Pellegrini A, Zweifel HR, von Fellenberg R.The alpha-2-protease inhibitor, of 65,000 daltons molecular weight, described by several authors in horse plasma and also present as a contaminant in alpha-1-isoinhibitor isolates previously described by us (Pellegrini & von Fellenberg (1980) Biochim. biophys. Acta 616, 351-361) has now been isolated to purity and identified as antithrombin III. The inhibitor is composed of a single polypeptide chain as judged by SDS polyacrylamide gel electrophoresis. The inhibitor was effective only against trypsin and thrombin. Serological cross-reaction existed between the inhibitor and the antiserum t...
Stephens KA, Morcom E, Hood DM.A fluorometric assay was used to determine plasma antithrombin III (AT III) activities in 15 healthy adult horses. Nearly all plasma samples had an initial value of greater than 100% thrombin inhibited, so a 1:1 dilution of the prepared samples was performed. Following dilution, the mean value of the animals was 59.17 +/- 7.4% thrombin inhibited. Mares had significantly greater AT III activity than did geldings (P less than 0.01). The results of this study indicate the horse has more AT III activity than did other domestic species in which AT III activity has been reported.
