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Topic:Platelets
Platelets are small, anucleated cell fragments derived from megakaryocytes in the bone marrow, playing a key role in hemostasis and thrombosis in horses. They contribute to the formation of blood clots by adhering to the site of vascular injury, aggregating with one another, and facilitating the coagulation process. In equine medicine, platelet count and function are important parameters in assessing bleeding disorders and thrombotic conditions. Variations in platelet count can indicate underlying health issues, such as inflammation, infection, or bone marrow disorders. This page compiles peer-reviewed research studies and scholarly articles that explore the physiology, pathology, and clinical implications of platelets in equine health.
Effects of mesenchymal stem cells isolated from amniotic fluid and platelet-rich plasma gel on severe decubitus ulcers in a septic neonatal foal. This paper documents the treatment of severe decubitus ulcers with amniotic fluid mesenchymal stem cells and platelets rich plasma (PRP) gel in a septic neonatal foal. The colt needed 25 days of hospitalization: during this period ulcers were treated for 15 days with mesenchymal stem cells (MSCs) plus PRP, PRP gel alone, or aloe gel. Healing was faster using MSCs+PRP, and at 7 months an ulcer treated with aloe gel was still not completely healed.
Evaluation of the automated hematology analyzer Sysmex XT-2000iV™ compared to the ADVIA® 2120 for its use in dogs, cats, and horses: Part I–precision, linearity, and accuracy of complete blood cell count. The automated laser-based hematology analyzer Sysmex XT-2000iV™ providing a complete blood cell count (CBC) and 5-part differential has been introduced in large veterinary laboratories. The aim of the current study was to determine precision, linearity, and accuracy of the Sysmex analyzer. Reference method for the accuracy study was the laser-based hematology analyzer ADVIA® 2120. For evaluation of accuracy, consecutive fresh blood samples from healthy and diseased cats (n = 216), dogs (n = 314), and horses (n = 174) were included. A low intra-assay coefficient of variation (CV) of approxim...
Pulmonary inflammation due to exercise-induced pulmonary haemorrhage in Thoroughbred colts during race training. This study investigated the putative roles of inflammation and platelet-activating factor (PAF) in exercise-induced pulmonary haemorrhage (EIPH). Two-year-old Thoroughbred colts (n=37) were exercised on a racetrack for 5months before commencement of the study. Each colt was then exercised at 15-16m/s over 800-1000m and broncho-alveolar lavage fluid (BALF) was collected 24h later. The colts were subsequently divided into two groups on the basis of BALF analysis; an EIPH-positive group (presence of haemosiderophages, n=23) and an EIPH-negative group (absence of haemosiderophages, n=14). BALF fro...
Performance evaluation of the Sysmex pocH-100iV Diff hematology analyzer for analysis of canine, feline, equine, and bovine blood. The Sysmex pocH-100iV Diff is an impedance hematology analyzer recently introduced for point-of-care use in veterinary practices in Europe. Objective: The purpose of this study was to validate the pocH-100iV Diff for analysis of blood samples from dogs, cats, horses, and cattle. Methods: Fresh EDTA-blood samples from healthy and ill dogs (115), cats (94), horses (91), and cattle (78) were analyzed on the pocH-100iV Diff and the Cell-Dyn 3500. Results of the automated WBC differential counts were compared with the manual differential counts for 77 dogs, 65 cats, 40 horses, and 46 cattle. HCT we...
Evaluation of the Mythic 18 hematology analyzer for use with canine, feline, and equine samples. The Mythic 18 is a fully automated hematology bench-top analyzer using impedance technology for a complete blood cell count (CBC) and a 3-part white blood cell count (WBC) differential. The purpose of the current study was to evaluate the Mythic for assessment of agreement, precision, linearity, carry-over, stability, and usability under practice conditions. Ethylenediamine tetra-acetic acid-blood samples from 122 dogs, 140 cats, and 123 horses were analyzed with the Mythic and reference methods (Sysmex XT-2000iV, manual hematocrit, and microscopic WBC differentiation). Pearson's coefficient o...
Stimulus-dependent release of tissue-regenerating factors by equine platelets. Platelet-rich plasma (PRP) is increasingly used for treatment of orthopaedic injuries. However, the effects of different stimuli on the release pattern of regenerative and proinflammatory factors from equine platelets are largely unknown and an optimal treatment protocol remains to be established. Objective: The aim of this study was to identify a stimulus that enhanced release of histopromotive factors (platelet-derived growth factor BB [PDGF] and transforming growth factor 1β[TGF]) without causing concurrent release of a proinflammatory mediator (CCL5). Methods: Washed platelets were prepar...
Effects of hydrocortisone and aminophylline on the aggregation of equine platelets in vitro. The purpose of this study was to evaluate in vitro the effects of hydrocortisone and aminophylline on adenosine diphosphate (ADP)-induced platelet aggregation in horses. Blood samples from 30 healthy Thoroughbred horses were collected by via jugular venipuncture to assess platelet aggregation. Platelet-rich and platelet-poor plasma were prepared from all samples by centrifugation and divided into three different aliquots. In the first aliquot, platelet aggregation was measured after platelet activation with 1 µM and 0.5 µM ADP (Group A). In the other two aliquots, the effect of a 10 min prei...
Evaluation of a filter-prepared platelet concentrate for the treatment of suspensory branch injuries in horses. Platelet preparations have become a treatment for soft tissue injuries in horses. This study evaluated a novel filter-based system to concentrate platelets and assesses its value in the treatment of suspensory ligament branch desmitis. Methods: Filtered platelet concentrate was prepared from 55 ml of venous blood obtained from 21 normal horses. Platelets and white blood cells in whole blood and filtered platelet concentrate were measured, as was platelet activating factor (PAF)-induced platelet-derived growth factor-BB (PDGF-BB) release. Eleven horses with 18 focal acute suspensory ligament br...
Autologous biologic treatment for equine musculoskeletal injuries: platelet-rich plasma and IL-1 receptor antagonist protein. Autologous biologic therapies such as platelet-rich plasma and autologous conditioned serum are in widespread clinical use to treat musculoskeletal pathology in horses. These substances exert a therapeutic effect through the provision of either anabolic or anti-catabolic factors, or a combination of both. This article discusses the history, experimental and clinical literature, and currently accepted preparation and usage strategies for both platelet-rich plasma and autologous conditioned serum.
Coagulation profiles of healthy Andalusian donkeys are different than those of healthy horses. Coagulation disorders are frequently diagnosed, especially in hospitalized equidae, and result in increased morbidity and mortality. However, hemostatic reference intervals have not been established for donkeys yet. Objective: To determine whether the most common coagulation parameters used in equine practice are different between healthy donkeys and horses. Methods: Thirty-eight healthy donkeys and 29 healthy horses. Methods: Blood samples were collected to assess both coagulation and fibrinolytic systems by determination of platelet count, fibrinogen concentration, clotting times (prothrombi...
In-vitro hypocoagulability on whole blood thromboelastometry associated with in-vivo expansion of red cell mass in an equine model. In several species, there is a strong correlation between indicators of red cell mass (RCM) and thromboelastometry results. The horse has a reliable, temporary, polycythemia in response to phenylephrine infusion. Our objective was to evaluate the effects of an in-vivo increase in circulating RCM on thromboelastometry results in an equine model of transient polycythemia. Six healthy research horses had whole blood thromboelastometry with contact activator and tissue factor initiation after recalcification of citrated samples. Additional samples were frozen for thrombin-antithrombin (TAT). Compl...
Disturbance of oxidant/antioxidant equilibrium in horses naturally infected with Trypanosoma evansi. Oxidant/antioxidant equilibrium disturbance has already been reported in trypanosome infections by several authors. The present study was aimed to explore the possible oxidant/antioxidant disturbance in surra of naturally infected horses before and after treatment. Fifteen naturally infected horses were chosen to analyse erythrocytic indices, platelet counts, lipid peroxides (LPO), nitric oxide (NO), reduced glutathione (GSH), superoxide dismutase (SOD) and catalase (CAT) while six healthy animals acted as control. There was a highly significant (P<0.001) reduction in red blood cell (RBC) c...
Regenerative medicine for the treatment of musculoskeletal overuse injuries in competition horses. Tissue repair in musculoskeletal injuries is often a slow and sometimes incomplete process. Regenerative medicine based on the use of growth factors (GFs) and cell therapy is aimed at improving the quality and speed of tendon and ligament healing. The aim of this study was to evaluate the potential for the administration of a combination of autologous platelet-rich plasma (PRP) and freshly isolated bone marrow mononucleated cells (BMMNCs) in 13 competition horses affected by overuse musculoskeletal injuries (suspensory ligament desmopathy and superficial flexor tendinopathy) and refractory to ...
Glanzmann thrombasthenia in a 17-year-old Peruvian Paso mare. A 17-year-old Peruvian Paso mare was evaluated for bilateral epistaxis that had been present for at least 3 years. The mare had mild anemia, platelet count within the reference interval, unremarkable coagulation times, and a negative Coggins test. On endoscopic examination, structural abnormalities were not observed in the nasal cavities, pharynx, larynx, trachea, or either guttural pouch, but petechiation was noted in the nasal mucosa. Additional tests revealed prolonged cutaneous bleeding time, normal concentration of von Willebrand factor antigen, an abnormal clot retraction test, and failu...
Effects of preparation method, shear force, and exposure to collagen on release of growth factors from equine platelet-rich plasma. To test the hypotheses that preparation method, exposure to shear force, and exposure to collagen affect the release of growth factors from equine platelet-rich plasma (PRP). Methods: PRP obtained from 6 horses. Methods: PRP was prepared via 2 preparation methods (tube and automated) and subjected to 6 treatment conditions (resting, detergent, exposure to shear via 21- and 25-gauge needles, and exposure to collagen [10 and 20 μg/mL]). Concentrations of platelet-derived growth factor, isoform BB (PDGF-BB); transforming growth factor β, isoform 1 (TGFβ₁); and insulin-like growth factor, iso...
Effects of clopidogrel and aspirin on platelet aggregation, thromboxane production, and serotonin secretion in horses. Critically ill horses are susceptible to thrombotic disease, which might be related to increased platelet reactivity and activation. Objective: To compare the effect of oral clopidogrel and aspirin (ASA) on equine platelet function. Methods: Six healthy adult horses. Methods: Horses received clopidogrel (2 mg/kg p.o. q24h) or ASA (5 mg/kg p.o. q24h) for 5 days in a prospective randomized cross-over design. Platelet aggregation responses to adenosine diphosphate (ADP) and collagen via optical aggregometry, and platelet secretion of serotonin (5HT) and production of thromboxane B(2) (TXB(2) ) by...
Effect of different workload and hydrocortisone in vitro on platelet aggregation in athletic horse. The objective of the present study was to evaluate the platelet response to different workload in athletic horse and the influence of hydrocortisone on this response. For this purpose, six Sella Italiana gelding athletic horses, ranging in age from 8 to 10 years and clinically healthy, were subjected to four different exercises: horse-walker, treadmill, obstacle course of 1.00 m and obstacle course of 1.25 m. From all the horses, citrated plasma samples were collected at rest, immediately after exercise and 30 min after the end of the exercise to assess the maximum degree of platelet aggregati...
The secretory mechanisms in equine platelets are independent of cytoskeletal polymerization and occur through membrane fusion. Studies in animal models are useful to understand the basic mechanisms involved in hemostasis and the functional differences among species. Ultrastructural observations led us to predict differences in the activation and secretion mechanisms between equine and human platelets. The potential mechanisms involved have been comparatively explored in the present study. Equine and human platelets were activated with thrombin (0.5 U/ml) and collagen (20 µg/ml), for 90 seconds, and samples processed to evaluate: i) ultrastructural changes, by electron microscopy, ii) actin polymerization and cy...
Thromboelastography in healthy horses and horses with inflammatory gastrointestinal disorders and suspected coagulopathies. 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...
Pregnancy influences the hematological profile of Carthusian broodmares. In order to investigate the effect of pregnancy on equine hematological profile, venous blood samples were taken from 44 Carthusian broodmares every two weeks during pregnancy, divided into three periods: I (conception to 110 days), II (111-220 days) and III (222 days to delivery). Routine hematological analysis was performed. Packed cell volume (PCV) increased in period II probably as a consequence of the climatic conditions or as a result of physical stress of lactation during period I. After that, a reduction in PCV was found but this was not matched with a similar decrease in total serum p...
The effects of pentoxifylline on equine platelet aggregation. Pentoxifylline (PTX) possesses a number of vasomotor, immunomodulatory, and hemorheologic properties. Based upon the hypothesis that equine laminitis and navicular disease result from microthrombosis, the inhibitory effects of PTX on inflammatory cytokines, and its inhibitory effects on human platelet aggregation, PTX has been widely used to treat equine endotoxemia, navicular disease, and laminitis. Despite this, the effects of PTX on equine platelet aggregation have not been investigated previously. Objective: PTX decreases platelet aggregation in equine whole blood at concentrations approxi...
Modulation of peripheral markers of the serotoninergic system in healthy horses. To evaluate the changes in plasma and platelet serotonin (5-HT) as markers of the serotoninergic system in equines, 5-HT content was measured by high performance liquid chromatography (HPLC) in deproteinized plasma obtained from peripheral blood samples of 12 clinically healthy horses, before and after feeding. 5-HT was measured in platelet rich plasma (PRP) and in platelet poor plasma (PPP). 5-HT in platelets (p5-HT) was obtained by subtracting free 5-HT in PPP (f5-HT) from 5-HT in PRP. After food ingestion, significant increases in p5-HT and f5-HT (p < 0.001), and no changes in the f5-HT/...
Evaluation of the effect of phosphodiesterase on equine platelet activation and the effect of antigen challenge on platelet phosphodiesterase activity in horses with recurrent airway obstruction. To determine whether expression of equine platelet activation-dependent surface markers is influenced by phospodiesterase (PDE) isoenzyme activity and whether antigen challenge alters platelet PDE activity in horses with recurrent airway obstruction (RAO). Methods: 16 horses. Methods: 7 healthy horses were used for in vitro experiments, 6 horses with RAO were used for antigen challenge, and 6 healthy horses were used as control animals. Three of the healthy horses had also been used in the in vitro experiments. Effects of PDE inhibition and activation of adenylyl cyclase on CD41/61 and CD62P e...
The effect of platelet-rich plasma on the neovascularization of surgically created equine superficial digital flexor tendon lesions. The repair process of tendon injuries, which are common in both human and equine athletes, is slow and the quality of the repair tissue is often inferior to the original tendon tissue, which frequently leads to re-injury. The relatively poor vascularization of tendons is considered to be one of the reasons for their limited healing potential. Recently, platelet-rich plasma (PRP), an autologous concentrate of platelets, rich in growth factors, has been shown to enhance the repair process of injured tendons. This effect has been ascribed to the high levels of growth factors in PRP, several of wh...
Platelet-activating factor and evidence of oxidative stress in the bronchoalveolar fluid of Thoroughbred colts during race training. Inflammatory airway disease (IAD) is prevalent in young racehorses during training, being the 2nd most commonly diagnosed ailment interrupting training of 2-year-old Thoroughbred racehorses. Objective: That stabling and exercise cause oxidative stress, release of platelet-activating factor (PAF) and inflammation in airways of Thoroughbred colts. Methods: Colts in breeding farms (NC, n = 45), stabled for 30 days (EC, n = 40), and race trained (EX, n = 34). Methods: Cytological profile and parameters of bronchoalveolar lavage fluid (BALF) related to oxidative stress, bioactivity of the proinflam...
Platelet-derived growth factor acts via both the Rho-kinase and p38 signaling enzymes to stimulate contraction in an in vitro model of equine wound healing. Horses are more prone to complications in the wound healing process than other species, and problems such as chronic inflammation, delayed epithelialization, poor wound contraction, and exuberant granulation tissue are commonly seen, particularly in wounds on the distal limbs. In comparison, wounds of the oral mucosa heal rapidly in a scarless fashion with a high degree of wound contraction. The effect of platelet-derived growth factor BB (PDGF), insulin-like growth factor (IGF)-1, and transforming growth factor beta1 (TGFbeta1) on the contraction of a fibroblast-populated collagen matrix (FPC...
Hyperleptinemia in horses: responses to administration of a small dose of lipopolysaccharide endotoxin in mares and geldings. Mares and geldings in good body condition selected for hyperleptinemia vs. normal leptin concentrations were studied to determine whether the hyperleptinemic condition affected various characteristics of the hematologic and hormonal systems after a challenge with lipopolysaccharide endotoxin. Four mares and 4 geldings that were determined to be hyperleptinemic (mean plasma leptin concentrations of 10.0 to 15.5 ng/mL) and 4 mares and 4 geldings with mean plasma leptin concentrations between 2.4 and 5.5 ng/mL were administered Escherichia coli O55:B5 endotoxin (35 ng/kg of BW in 500 mL of saline...
Computerised analysis of standardised ultrasonographic images to monitor the repair of surgically created core lesions in equine superficial digital flexor tendons following treatment with intratendinous platelet rich plasma or placebo. The effectiveness of new therapies to treat tendon injuries is difficult to determine and is often based on semi-quantitative methods, such as grey level analysis of ultrasonographic images or subjective pain scores. The alternatives are costly and long-lasting end-stage studies using experimental animals. In this study, a method of ultrasonographic tissue characterisation (UTC), using mathematical analysis of contiguous transverse ultrasonographic images, was used for intra-vital monitoring of the healing trajectory of standardised tendon lesions treated with platelet rich plasma (PRP) or pla...
Effects of platelet-rich plasma on the quality of repair of mechanically induced core lesions in equine superficial digital flexor tendons: A placebo-controlled experimental study. Tendon injuries are notorious for their slow and functionally inferior healing. Intratendinous application of platelet-rich plasma (PRP) has been reported to stimulate the repair process of tendon injuries, but there is little conclusive evidence for its effectiveness. A placebo-controlled experimental trial was performed to test the hypothesis that a single intratendinous PRP treatment enhances the quality of tendon repair, as evidenced by improved biochemical, biomechanical, and histological tissue properties. In six horses, tendon lesions were created surgically in the Superficial Digital F...
Effects of platelet-rich plasma gel on skin healing in surgical wound in horses. To establish a low-cost method to prepare platelet-rich plasma (PRP) and evaluates the potential of platelet derived factors to enhance wound healing in the surgical wounds in equine. Methods: To obtain a PRP gel, calcium gluconate and autologous thrombin were added to platelet-rich plasma. For the tests six saddle horses were used and two surgical incisions were made in each animal. Wounds were treated with PRP gel or untreated. Sequential wound biopsies collected at Treatment 1: at days 5 and 30 and Treatment 2: at days 15 and 45 post wounding permitted comparison of differentiation markers ...
