Omneity® Pellets
All-In-One Vitamin & Mineral Pellet
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.
Preliminary evaluation of hemostasis in neonatal foals using a viscoelastic coagulation and platelet function analyzer. To compare coagulation and platelet function parameters measured using a viscoelastic analyzer in 3 groups: foals presenting to a neonatal intensive care unit with presumed sepsis, normal foals, and adult horses. Methods: Preliminary prospective trial. Methods: Veterinary teaching hospital. Methods: Ten clinically healthy foals, 13 clinically healthy adult horses, and 17 foals sequentially admitted for suspected sepsis. Intervention- A single citrated (3.8%) blood sample collected at admission was submitted for coagulation evaluation using a viscoelastic analyzer. Results: Time to initial clot...
Comparison of viscoelastic coagulation analysis and standard coagulation profiles in critically ill neonatal foals to outcome. 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...
Thrombelastography in 26 healthy horses with and without activation by recombinant human tissue factor. 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 ...
Stability and reproducibility of ADVIA 120-measured red blood cell and platelet parameters in dogs, cats, and horses, and the use of reticulocyte haemoglobin content (CH(R)) in the diagnosis of iron deficiency. Modern laser-based haematology analysers such as the ADVIA 120 have species-specific software and offer the possibility of assessing new haematological parameters. These parameters have yet to be evaluated, and as these analysers are often used in referral laboratories, it is important to know whether the values of haematological parameters change during sample transport. Therefore, samples of EDTA-anticoagulated blood from nine healthy dogs and EDTA- and citrate-anticoagulated blood from six healthy horses were collected and stored at room temperature for 72 and 48 hours, respectively. In can...
Validation of the Sysmex XT-2000iV hematology system for dogs, cats, and horses. I. Erythrocytes, platelets, and total leukocyte counts. The Sysmex XT-2000iV is a laser-based, flow cytometric hematology system that has been introduced for use in large and referral veterinary laboratories. Objective: The purpose of this study was to validate the Sysmex XT-2000iV for counting erythrocytes, reticulocytes, platelets, and total leukocytes in blood from ill dogs, cats, and horses. Methods: Blood samples from diseased animals (133 dogs, 65 cats, and 73 horses) were analyzed with the Sysmex XT-2000iV and the CELL-DYN 3500. Manual reticulocyte counts were done on an additional 98 canine and 14 feline samples and manual platelet counts w...
Neutrophil and platelet activation in equine recurrent airway obstruction is associated with increased neutrophil CD13 expression, but not platelet CD41/61 and CD62P or neutrophil-platelet aggregate formation. Recurrent airway obstruction (RAO) in mature horses is characterized by reversible airway obstruction and neutrophilic inflammation; there is also functional activation of circulating platelets and neutrophils. This study was undertaken to determine if changes in activation marker expression and heterotypic aggregate formation can be used as an indicator of this increased functional responsiveness. In vitro conditions for flow cytometric measurement of CD13, CD41/61 and CD62P expression on activated cells and heterotypic aggregate formation were established. Values were then compared before an...
Regulation of platelet activating factor-induced equine platelet activation by intracellular kinases. Lipopolysaccharide (LPS) can activate equine platelets directly or indirectly, via leukocyte-derived platelet activating factor (PAF). Thromboxane (Tx) production by LPS-stimulated equine platelets requires p38 MAPK and this kinase has been suggested as a therapeutic target in endotoxaemia. The present study has utilised selective inhibitors to investigate the role of p38 MAPK and two other kinases, phosphatidylinositol-3 kinase (PI3K) and protein kinase C (PKC), in regulating PAF-induced Tx production, aggregation and 5-HT release in equine platelets, and the modification of these responses b...
Effects of platelet-rich plasma on the repair of wounds on the distal aspect of the forelimb in horses. To evaluate the effect of platelet-rich plasma on wounds on the distal aspect of the forelimb in horses. Methods: 6 mixed-breed 10- to 15-year-old mares. Methods: 3 wounds were created on metacarpal regions in each of 6 horses (n = 36 wounds total). Eighteen wounds were treated with platelet-rich plasma and bandaged, whereas 18 control wounds were similarly bandaged with no prior topical treatment. Decrease in wound surface area and the required number of excisions of exuberant granulation tissue were recorded until complete healing. Tissue specimens were taken from wounds at 1 week for histol...
Plasma concentrations of endotoxin and platelet activation in the developmental stage of oligofructose-induced laminitis. The link between the fermentation of carbohydrate in the equine large intestine and the development of acute laminitis is poorly understood. Absorption of endotoxin (lipopolysaccharide; LPS) into the plasma has been observed in one experimental model of laminitis, but does not cause laminitis when administered alone. Thus, the potential role of endotoxin is unclear. Platelet activation has previously been demonstrated in the developmental stage of laminitis. Equine platelets are more sensitive than leukocytes to activation by endotoxin, and can be activated directly by LPS in the low pg/ml ran...
Assessment of platelet growth factors in supernatants from rehydrated freeze-dried equine platelets and their effects on fibroblasts in vitro. To determine whether platelet growth factors are preserved in supernatants obtained from rehydrated trehalose-stabilized, freeze-dried (lyophilized) equine platelets and whether those growth factors stimulate fibroblast proliferation and migration and enhance fibroblast-associated contraction in a collagen gel assay. Methods: 6 clinically normal adult horses. Methods: Blood samples were obtained from 6 horses, and washed platelets were prepared via differential centrifugation. Washed platelets were freeze-dried in a physiologic buffer with a mixture of trehalose and polyethylene glycol 4000. R...
Characteristics, diagnosis, and treatment of inherited platelet disorders in mammals. Inherited intrinsic platelet disorders have been identified in dogs, cattle, horses, and cats as well as other animals. The prevalence of mutations in some breeds is high, making these disorders potentially as common as von Willebrand disease in certain breed lineages.
Expression of platelet-derived growth factor-beta receptor and bovine papillomavirus E5 and E7 oncoproteins in equine sarcoid. Equine sarcoids are benign fibroblastic skin tumours that are recognized throughout the world. Infection with bovine papillomavirus (BPV) types 1 and 2 has been implicated as a major factor in disease development; however, the cellular mechanisms underlying fibroblast transformation remain poorly defined. The present study further characterizes aspects of the association with BPV in 15 equine sarcoids. BPV DNA was demonstrated in 12/15 tumours collected from different areas of Italy. Nine of these 12 tumours expressed the BPV oncoproteins E5 and E7, but these oncoproteins were not expressed by...
Equine adipose-tissue derived mesenchymal stem cells and platelet concentrates: their association in vitro and in vivo. Equine mesenchymal stem cells (MSC) are of particular interest both for basic research and for the therapeutic approach to musculoskeletal diseases in the horse. Their multilineage differentiation potential gives them the capability to contribute to the repair of tendon, ligament and bone damage. MSCs are also considered a promising therapeutic aid in allogeneic cell transplantation, since they show low immunogenicity and immunomodulating functions.Adipose tissue-derived adult equine stem cells (AdMSC) can be isolated, expanded in vitro and then inoculated into the damaged tissue, eventually i...
Intralesional injection of platelet-rich plasma followed by controlled exercise for treatment of midbody suspensory ligament desmitis in Standardbred racehorses. To determine outcome of Standardbred racehorses with moderate to severe midbody suspensory ligament desmitis (MSD) treated by means of ultrasound-guided intralesional injection of a single dose of platelet-rich plasma (PRP) followed by a program of gradually increased exercise. Methods: Nonrandomized clinical trial. Methods: 9 Standardbred racehorses. Methods: Following injection of PRP, horses were allowed a controlled, gradual return to exercise. Race records for the year prior to injury and for 3 consecutive years after horses returned to racing were reviewed. For comparison purposes, race ...
Evaluation of equine hemograms using the ADVIA 120 as compared with an impedance counter and manual differential count. The ADVIA 120 is an automated laser cell counter widely used in veterinary medicine. Although specific software for equine samples is available and validated, only a few reports have been published comparing the ADVIA 120 with other methods for equine hemogram evaluation. Objective: The purpose of this study was to compare the hematologic values and reference intervals obtained on the ADVIA 120 with those obtained on an impedance cell counter and manual differential counts in healthy horses. Methods: EDTA-anticoagulated blood samples were obtained from 114 clinically healthy horses of various ...
Determination of the source of increased serotonin (5-HT) concentrations in blood and peritoneal fluid of colic horses with compromised bowel. Increased plasma (5-HT) concentrations are reported in horses predisposed to develop laminitis and after i.v. infusion of endotoxins. In the equine jejunum contractile 5-HT1A-like receptors show tachyphylaxia upon prolonged activation with 5-HT. Therefore, increased systemic 5-HT release in colic horses could play a possible role in the pathophysiology of ileus. Objective: To investigate possible increased systemic release of 5-HT in colic horses with compromised bowel and to identify the source of 5-HT overload. Methods: Concentrations of 5-HT were determined in plasma and peritoneal fluid (P...
Poor reproducibility of template bleeding time in horses. Template bleeding time (TBT) is considered to be a useful test for detecting platelet function disorders and the effect of platelet-activating drugs, but studies in human medicine have concluded that the test has poor reproducibility and sensitivity. Objective: TBT has poor reproducibility in horses and has insufficient sensitivity to detect the effect of etamsylate on platelet function. Methods: Twenty healthy horses. Methods: TBT was determined and repeated 2 hours and 30 days later. TBT was also performed 2 hours after IV administration of etamsylate. Results: Although no statistical differ...
Autologous platelet concentrates as a treatment for musculoskeletal lesions in five horses. Two horses with acute tendinopathy of a superficial digital flexor tendon (SDFT) and three horses with chronic proximal desmitis of the suspensory ligament (PDSL) were treated by injecting autologous concentrates of their platelets into the lesions. The lesions were monitored ultrasonographically and clinically. There were significant ultrasonographic and clinical improvements in the two horses with SDFT, but no ultrasonographic improvements in the horses with PDSL; however, they improved clinically and became less lame. All the horses had returned to their pre-injury level of performance by s...
Roles of thromboxane A2 and 5-hydroxytryptamine in endotoxin-induced digital vasoconstriction in horses. To evaluate the roles of 5-hydroxytryptamine (5-HT), thromboxane A2 (TxA2), and platelet-activating factor (PAF) in endotoxin-induced digital hypoperfusion in horses. Methods: 6 healthy adult Thoroughbreds. Methods: Horses were treated with IV administration of saline (0.9% NaCl) solution (control treatment) or the 5-HT 1B/D selective antagonist, GR55562 (0.3 mg/kg), prior to tryptamine infusion (1.6 microg/kg/min for 30 minutes) to establish an effective GR55562 dose. In a crossover study, horses were treated with IV administration of saline solution (control treatment), aspirin (4 mg/kg, 2 h...
The ultrastructure of camel blood platelets: a comparative study with human, bovine, and equine cells. Previous studies indicated that the camel has a very active haemostatic mechanism with a short bleeding time and thrombocytosis. However, platelet function, when tested by agonist-induced aggregation and PFA 100 closure time, showed marked inhibition compared to humans. Since camels are also far more resistant to long exposure to excessive heat and high body temperature than humans, it seemed worthwhile to explore fundamental morphological differences between human and camel platelets and those from other species. The present study has examined the ultrastructure of camel platelets and compare...
Platelet activation in ponies with airway inflammation. Platelet activation occurs in human obstructive airway diseases and in laboratory animal models. However, there is limited evidence that platelets may be involved in equine recurrent airway obstruction (RAO) and other inflammatory diseases. This study investigated whether platelet activation also occurred in RAO. Objective: Platelet function is altered in ponies with active RAO. This alteration can be detected ex vivo by measuring platelet adhesion. Methods: An in vitro platelet adhesion assay measuring acid phosphatase (AcP) activity colorimetrically was adapted for use with equine platelets ...
Phosphodiesterase isoenzymes in equine platelets and their influence on platelet adhesion. To determine the phosphodiesterase (PDE) isoenzymes in equine platelets and evaluate their influence on platelet adhesion. Methods: Platelets obtained from healthy New Forest Pony geldings that ranged from 12 to 20 years of age (mean +/- SEM, 17.3 +/- 1.1 years). Methods: PDE isoenzyme activity in equine platelets was determined by use of a 2-step radioactive assay. Functional importance of PDE isoenzymes was established by use of selective inhibitors in a colorimetric adhesion assay. Results: PDE1, PDE2, PDE3, and PDE5 and small amounts of PDE4 were found in equine platelets. Inhibition of PD...
Mean platelet component as an indicator of platelet activation in foals and adult horses. Mean platelet component (MPC) is a new platelet variable, measured by modern commercial complete blood count analyzers, that is reduced during platelet activation in humans and small animals. Objective: MPC decreases in horses with clinical conditions that cause platelet activation and disseminated intravascular coagulation (DIC). Methods: We obtained 418 CBCs from 100 sick and 20 healthy neonates and 178 sick and 45 sound adult horses. Sick neonates were classified into septic and nonseptic, and DIC and non-DIC groups. Adults were grouped by diagnoses (systemic inflammatory disorders, gastroi...
Pharmacokinetics and pharmacodynamics of epsilon-aminocaproic acid in horses. To determine the pharmacokinetics and pharmacodynamics of epsilon-aminocaproic acid (EACA), including the effects of EACA on coagulation and fibrinolysis in healthy horses. Methods: 6 adult horses. Methods: Each horse received 3.5 mg of EACA/kg/min for 20 minutes, i.v. Plasma EACA concentration was measured before (time 0), during, and after infusion. Coagulation variables and plasma alpha(2)-antiplasmin activity were evaluated at time 0 and 4 hours after infusion; viscoelastic properties of clot formation were assessed at time 0 and 0.5, 1, and 4 hours after infusion. Plasma concentration ver...
Prevalence of reduced fibrinogen binding to platelets in a population of Thoroughbreds. To measure the frequency and magnitude of reduced fibrinogen binding in a population of horses from a Thoroughbred breeding farm. Methods: 444 Thoroughbred horses, 1 to 27 years old, including 316 females, 72 geldings, and 56 sexually intact males. Methods: Blood was collected from horses into tubes containingacid citrate dextrose adenine, and washed platelets were examined by use of flow cytometry for their ability to bind fibrinogen. Results: Data regarding fibrinogen binding to activated platelets were normally distributed, with nearly identical amounts of variation regardless of sex. In 3 ...
Glanzmann thrombasthenia in an Oldenbourg filly. An 18-month-old Oldenbourg filly was presented with a bleeding diathesis. Laboratory testing included platelet count, gingival bleeding time, prothrombin time (PT), activated partial thromboplastin time (aPTT), von Willebrand factor (vWf) antigen, clottable fibrinogen, clot retraction time, PFA-100 closure time, platelet aggregometry (on platelet-rich plasma), and thrombelastography (TEG). TEG was performed by using kaolin and tissue factor as coagulation activators. Expression of the platelet receptor for fibrinogen was assessed by flow cytometry by using anti CD41 (alpha(IIb) or glycoprotein...
Clinical evaluation of the CA530-VET hematology analyzer for use in veterinary practice. The CA530-VET is a completely automated impedance cell hematology analyzer, which yields a 16-parameter blood count including a 3-part leukocyte differential. Objective: The aim of this study was to examine the operational potential of the CA530-VET and its value for use in veterinary practice. Methods: The analyzer was tested for blood carry-over, precision, and accuracy. Comparison methods included the CELL-DYN 3500, microhematocrit centrifugation, manual platelet (PLT) counting for feline and equine species, and a 100-cell manual WBC differential. Blood samples for comparison of the methods...
The effect of physical exercise on the daily rhythm of platelet aggregation and body temperature in horses. The goal of this study was to investigate the influence of physical activity on the daily rhythm of platelet aggregation and body temperature in horses. Blood samples from 12 Thoroughbred horses, six sedentary animals and six athletes (studied both before and after a period of inactivity) were collected at 4h intervals for 48h via an intravenous cannula inserted into the jugular vein. Body temperature was recorded every 4h for 48h with a rectal probe. Platelet aggregation was measured with an aggregometer. Collagen was used to test the aggregation of the plasma samples. Statistical analysis of...
Serial alterations in digital hemodynamics and endothelin-1 immunoreactivity, platelet-neutrophil aggregation, and concentrations of nitric oxide, insulin, and glucose in blood obtained from horses following carbohydrate overload. To quantify changes in endothelium-derived factors and relate those changes to various aspects of digital hemodynamics during the prodromal stages of carbohydrate overload (CHO)-induced laminitis in horses. Methods: 20 adult horses without abnormalities of the digit. Methods: Digital and jugular venous blood samples were collected at 1-hour intervals (for assessment of endothelin-1 [ET-1] immunoreactivity and measurement of glucose, insulin, and nitric oxide [NO] concentrations) or 4-hour intervals (CBC and platelet-neutrophil aggregate assessment) for 8 hours or 16 hours after induction of CH...
