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Topic:Plasma
Plasma is the liquid component of blood in horses, consisting primarily of water, electrolytes, proteins, and waste products. It serves as a transport medium for nutrients, hormones, and waste products throughout the body. Plasma also plays a role in maintaining blood pressure and volume, as well as serving as a reservoir for critical proteins involved in clotting and immune responses. Research on equine plasma often focuses on its composition, functions, and applications in veterinary medicine, such as transfusions and diagnostic testing. This page compiles peer-reviewed research studies and scholarly articles that explore the properties, functions, and clinical applications of plasma in equine health.
Evaluation of a new immunoassay for measuring equine serum insulin and plasma adrenocorticotrophic hormone: A method comparison study. Insulin dysregulation (ID) and pituitary pars intermedia dysfunction (PPID) are common equine endocrinopathies detected by measurement of circulating insulin and adrenocorticotrophic hormone (ACTH) concentrations. Different assays may yield variable results, limiting comparability. Objective: To compare immunoassays developed specifically to measure equine insulin (VIDAS® Equine Insulin; enzyme-linked fluorescent assay [ELFA]) and equine ACTH (VIDAS® Equine ACTH; ELFA) with results obtained from a chemiluminescence immunoassay (CLIA) measured using IMMULITE 2000XPi, a chemiluminescence enzym...
Population Pharmacokinetics and Detection Times of Betamethasone After Intravenous, Intramuscular, and Intranasal Jet Administration of Betamethasone Sodium Phosphate in Horses. Betamethasone sodium phosphate (BETP) is a glucocorticosteroid used in humans. The primary objective was to estimate irrelevant plasma (IPC) and urine (IUC) concentrations using a pharmacokinetic/pharmacodynamic approach based on systemic clearance estimated from intravenous (IV) pharmacokinetic data. As a secondary objective, detection times (DTs) following IV, intramuscular (IM), and intranasal jet (INJ) administration were estimated for medication control. Plasma and urine concentrations were obtained from a total of 20 horses in Japan and Germany, with some horses contributing to more than...
Preliminary evaluation of beta-endorphin alone and in combination with adrenocorticotropic hormone for the diagnosis of pituitary pars intermedia dysfunction in equids. Limited published data exist regarding the diagnostic utility of beta-endorphin (β-END) for pituitary pars intermedia dysfunction (PPID), either compared with or in combination with adrenocorticotropic hormone (ACTH). Objective: To evaluate β-END as a potential diagnostic test for PPID in comparison with ACTH and to explore the diagnostic performance of combined tests. Methods: Ninety-eight equids aged 19-32 years, owned by the foundation "Stiftung für das Pferd," were included. Methods: A cross-sectional study was conducted in January 2025. Haircoat abnormalities were scored as absent, mi...
Pharmacokinetic/Pharmacodynamic Analysis of Quinidine-Induced Dominant Frequency Reduction in Thoroughbred Horses With Atrial Fibrillation. Quinidine has long been used for the pharmacological treatment of atrial fibrillation (AF) in horses; however, the plasma concentration required for conversion to sinus rhythm remains unclear. Dominant frequency (DF), derived from surface electrocardiograms, reflects atrial activation rate during AF. This study aimed to quantify the relationship between plasma quinidine concentration and DF using a pharmacokinetic/pharmacodynamic (PK/PD) approach. Ten Thoroughbred horses with naturally occurring AF received quinidine sulfate via a nasogastric tube. Plasma quinidine concentrations and DF values...
Plasma Homocysteine Concentrations in Horses with Left-Sided Valvular Heart Disease. In human medicine, homocysteine, a sulfur-containing amino acid, is used as a biomarker reflecting endothelial dysfunction, inflammation, thrombogenesis, oxidative stress and cardiovascular disease. An automated enzyme-cycling assay for homocysteine, established for humans, has been validated and reference ranges have been created for horses. In this study the homocysteine assay was further evaluated by assessing short-term stability (whole blood and plasma samples stored at 4 °C and room temperature for 24 h), long-term stability (two years), the effect of different anticoagulants (lithium h...
Plasma and Urinary Concentrations of Synephrine in Horses Following Controlled Oral Administration. Synephrine is a sympathomimetic alkaloid of regulatory interest in both horse racing and equestrian sports, where feed‑related exposure may lead to its detection in equine blood and urine. This study characterized plasma and urinary concentrations of synephrine in horses following controlled oral administration. Six Thoroughbred horses received single oral doses of 100 mg or 800 mg synephrine, and blood and urine samples were collected sequentially. Each sample was analyzed both before and after β‑glucuronidase hydrolysis, demonstrating that synephrine was present predominantly as conjuga...
Administration Study of Bedinvetmab, an Antinerve Growth Factor Monoclonal Antibody, in Horses for Doping Control Purposes. Monoclonal antibodies (mAbs) targeting nerve growth factor (NGF) represent a novel therapeutic approach for managing acute and chronic pain in humans and animals. However, their potential misuse as pain-masking agents in competitive equine sports raises significant welfare and integrity concerns. To enhance understanding of the elimination profile of anti-NGF mAb if misused in horses, this study describes the first administration of bedinvetmab (a canine anti-NGF mAb) in three geldings, establishing its plasma elimination profile following subcutaneous administration. Bedinvetmab plasma concen...
Untargeted Sweat Metabolomics and Targeted Plasma Amino Acid Profiling Reveal Dynamic Metabolic Remodeling During Conditioning in Yili Horses. Training induces sweat morphology changes in horses from muddy sweat (MS) to foamy sweat (FS) and clear sweat (CS), reflecting physiological adaptation. However, the metabolic mechanisms linking sweat phenotypes to systemic amino acid dynamics remain unclear. This study integrated sweat untargeted metabolomics and plasma amino acid targeted metabolomics to reveal coordinated metabolic remodeling. Six 2-year-old horse stallions underwent 10-week training. Plasma and sweat were sampled pre- and post-race at each stage. LC-MS/MS and UHPLC-MS/MS were used for sweat metabolome and plasma amino aci...
The progression values of heart rate and biochemical plasma parameters during training of 3-years old warmblood stallions for breeding licensing. Physiological adaptation to training in young sport horses remains incompletely characterized, particularly during standardized preparation for breeding licensing. Objective: The aim of this study was to evaluate cardiovascular and plasma biochemical responses to acute exercise and long-term training in three-year-old Czech Warmblood stallions during standardized free jumping exercise. Methods: Thirteen Czech Warmblood stallions were monitored over a 112-day training period. Heart rate parameters (minimum, maximum, and mean) were recorded during standardized free jumping tests. Plasma biochemi...
Towards a Comprehensive Screening Approach for Detecting Gene Doping in Racehorses and Sport Horses by Targeting Common and Intrinsic Plasmid Sequences. The evolution of biotechnology and gene therapy has unfortunately facilitated the emergence of gene doping. Those misused applications are prohibited in equestrian sports (International Equestrian Federation (FEI)) and in horseracing (International Federation of Horseracing Authorities [IFHA]), reflecting major concerns regarding horse welfare and the integrity of competitions. Among the biotechnological tools that could be misused, eukaryotic expression plasmids represent a particular threat due to their ease of production, customisable design and ability to carry a wide range of performance ...
Maternal age-related changes in renin-angiotensin-aldosterone system and electrolyte homeostasis during equine pregnancy. The renin-angiotensin-aldosterone system (RAAS) plays a key role in fluid and electrolyte homeostasis during pregnancy. In humans and laboratory animals, maternal age has been shown to modulate RAAS activity, potentially altering the secretion of renin (REN), angiotensin II (ANG-II), and aldosterone (ALD), thereby influencing sodium (Na⁺) and potassium (K⁺) regulation. Objective: To evaluate whether maternal age influences RAAS activity in pregnant mares. Methods: Forty-five Spanish Purebred mares were monitored monthly over 11 months of pregnancy and categorized into three age groups: You...
Transfer of passive immunity in foals: Can the plasma transfusion efficacy be predicted? The treatment for failure of transfer of passive immunity (FTPI) in foals with hyperimmune plasma has substantial variability of efficacy. Objective: The aims of the study were to assess the safety and efficacy of plasma transfusion and to investigate factors that may predict transfusion results, thereby allowing estimation of plasma volume requirements prior to transfusion. Methods: A retrospective review was conducted of foals admitted to an equine hospital that received a plasma transfusion for FTPI. Results: The study included 110 foals and 150 hyperimmune plasma transfusions. The median i...
Physiological determinants of plasma biochemical parameters in horses: a structured review. The biochemical profile of horses is a cornerstone in equine clinical diagnostics, offering valuable insights into health status, disease progression, and physiological adaptation to internal and external stimuli. However, the interpretation of these biochemical parameters is far from straightforward, as they are subject to significant variation influenced by a range of physiological factors. Age, sex, breed, level of physical activity, nutritional condition, and reproductive status can all modulate baseline biochemical values, potentially leading to diagnostic inaccuracies if not properly con...
Plasma and urinary exposure of cannabidiol and cannabidiolic acid in horses following consumption of contaminated feed. Cannabidiol (CBD) and cannabidiolic acid (CBDA) are non-psychoactive cannabinoids naturally present in hemp-derived products. While these compounds are prohibited during equine competition, horses may be inadvertently exposed through contaminated feed. Data describing systemic and urinary exposure to CBD and CBDA following such low-dose, involuntary intake are limited. This study aimed to describe plasma and urine concentration-time profiles of CBD and CBDA in horses after consumption of experimentally contaminated feed. Results: Twelve Standardbred horses received feed containing low doses (1...
Pharmacokinetics of Diclazuril in the Plasma and Cerebrospinal Fluid of Healthy Adult Horses After a Single Oral Dose Administered as a Pelleted Topdressing. Equine protozoal myeloencephalitis can cause acute infections with rapid onset of neurologic signs, necessitating immediate empiric therapy with antiprotozoal medication. The objective of the study was to identify when concentrations of diclazuril reached the MIC of Sarcocystis neurona in CSF (1 ng/mL) of healthy adult horses after a single oral dose. Six healthy adult horses were used. Blood and CSF were collected from indwelling intravenous jugular catheters and intrathecal catheters in the lumbosacral space prior to drug administration and then at 1-, 4-, 8-, 12-, 16-, 24-, 48-, 72-, 96-,...
Sensitive and selective quantification of elcatonin in equine plasma and urine using LC-FAIMS-MS/MS. The use of drugs for enhancing bone strength is prohibited under international regulations governing horse racing and equestrian sports. Elcatonin, a synthetic peptide with analgesic and bone-strengthening properties, is routinely monitored for compliance. However, its cyclic structure and high molecular weight hinder reliable detection. In this study, we developed and validated a sensitive liquid chromatography-high-field asymmetric waveform ion mobility spectrometry-tandem mass spectrometry method for quantifying elcatonin in equine plasma and urine. Sample preparation was optimised via weak...
Comparison of in vitro degradation of immunoreactive adrenocorticotropic hormone and insulin in equine blood measured by two immunoassay methods. This study compared the in vitro stability of equine plasma adrenocorticotrophic hormone (ACTH) and serum insulin measured by chemiluminescent assay (CLA; Siemens Immulite 2000XPi) and immunofluorescent assay (IFA; Tosoh AIA-900) after storage at 4°C or room temperature (approximately 21°C) for clinically relevant periods. Fresh equine EDTA blood for ACTH and coagulated blood for insulin were aliquoted and analysed immediately (T0) and after storage. ACTH was assessed at 24, 48 and 72 hours; insulin was assessed at 24 hours, 72 hours and 7 days. Percentage recovery relative to T0 was analyse...
Transference of diagnostic thresholds for equine plasma ACTH from the Immulite 1000 to Immulite 2000XPi and Tosoh AIA systems. Diagnosis of PPID in horses relies on measurement of plasma adrenocorticotrophic hormone (ACTH) concentrations. Because measured ACTH values vary between analytical platforms, and published diagnostic thresholds apply almost exclusively to the Immulite 1000 chemiluminescent assay (CLA), there is a need for validated, assay-specific thresholds for contemporary analysers. This study aimed to transfer and validate established Immulite 1000 diagnostic thresholds for plasma ACTH to three contemporary systems (Immulite 2000XPi, Tosoh AIA-900, and Tosoh AIA-360) using the Clinical Laboratory Standard...
Saliva and plasma metabolome analysis during the five days before foaling in the mare. Saliva is a relevant biofluid for real-time welfare-friendly monitoring of systemic events in animals, because some bioanalytes have a systemic origin and its collection is painless, stress-free and non-invasive. Our aim was to analyze the metabolome of equine saliva during the five days before foaling, with a focus on identifying metabolites whose level significantly changed before parturition, that could be potential salivary biomarkers of the onset of parturition. We compared the saliva and plasma metabolomes to investigate their relationship. Saliva and blood samples were collected from tw...
Plasma Concentrations Following Oral Administration of Two Different Forms of Resveratrol in Horses. Resveratrol is a compound found in multiple plants and there is evidence for its use as a supplement in horses, particularly through protection of chondrocytes. Previous studies on the clinical efficacy of resveratrol supplementation in horses have reported limited benefits. To date, there is no pharmacokinetic data of resveratrol in horses but the bioavailability of resveratrol in other species is poor. In this crossover study, the plasma concentrations of two forms of resveratrol were examined. Each horse received via nasogastric tube, either a single dose of resveratrol phospholipid or a st...
Effects of Dietary Non-Fibrous Carbohydrate to Neutral Detergent Fiber Ratio on Apparent Digestibility, Fecal Microbiota, and Plasma Metabolomics in Yili Horses. This study aimed to investigate the effects of dietary NFC/NDF ratio on nutrient apparent digestibility, fecal fermentation parameters, microbial diversity, and plasma metabolomics in Yili horses. Twenty-four healthy Yili horses with similar body weights (406 ± 22.73 kg) were divided into four groups, each with six replicates: the Control Group (CG), Low-NFC Group (LG), Medium-NFC Group (MG), and High-NFC Group (HG). The experiment lasted 52 d, comprising a 7-day adaptation period and a 45-day experimental period. Total fecal collection was conducted from days 41 to 45 to calculate nutrient a...
Plasma and Urinary Elimination Profiles of Medetomidine Metabolites in Horses for the Purpose of Doping and Medication Control. Medetomidine, an α₂-adrenergic agonist, is widely used as a sedative in horses. While its pharmacological effects are established, limited data exist on elimination of its metabolites, 3'-hydroxy medetomidine (HMD) and 3'-carboxy medetomidine (CMD), which are of regulatory interest. HMD is currently targeted in plasma and urine under International Screening Limits (ISLs) established by the International Federation of Horseracing Authorities (IFHA). In this study, seven Thoroughbreds received 6.3 μg/kg of medetomidine intravenously. Blood and urine were collected for 96 h and analyzed b...
Antibodies in plasma and blood cells of horses. Understanding the distribution of antibodies in the bloodstream is critical for advancing diagnostic and therapeutic approaches in veterinary medicine and comparative immunology. While most studies have focused on plasma antibodies, the presence and role of membrane-bound immunoglobulins remain underexplored, particularly in equine species such as the Jabe horse. Unassigned: This study aimed to analyze the amount of antibodies in the plasma and blood cells of Jabe horses for their potential future use. Unassigned: Blood samples were collected from Jabe horses and separated into plasma and cell...
Pharmacokinetic analysis and steady-state predictions of different preparations of metronidazole administered per rectum in adult horses. Manipulation of forms of rectally administered metronidazole to improve bioavailability in horses has not been reported. Objective: Evaluate the pharmacokinetics of 3 rectal metronidazole preparations compared to nasogastric (NG) administration. Methods: Seven healthy horses. Methods: Phase 1A was a randomized, 3-way crossover, single-dose pharmacokinetic study, and Phases 1B and 2 were non-randomized, single-dose follow-up studies. Metronidazole (20 mg/kg) was administered NG and rectally in water (RW20), as a rectal gel (RG), and in dimethyl sulfoxide (DMSO). Metronidazole (80 mg/kg) was a...
Pharmacokinetics of Topical Administration of Altrenogest in Mares and Implications for Human Health. Altrenogest is a synthetic progestogen widely used in equine reproductive management. Adverse effects to altrenogest have been reported in people with cutaneous exposure reported as the highest exposure pathway. Despite these reports, there has been no quantitative research to determine the capacity for altrenogest to be absorbed through skin. This study aimed to determine if cutaneous application of oral altrenogest results in systemic absorption in mares and to evaluate the influence of application site. A randomized, two-period, two-treatment crossover study was undertaken in eight mares. M...
The Effect of Lipemia on Insulin and Adiponectin Measurement in Equine Blood Samples. Lipemia is a common comorbidity in horses with obesity or equine metabolic syndrome, but the impact of lipemia on the measurement of insulin and adiponectin has not been evaluated. Objective: To evaluate endogenous and exogenous lipemic interference with equine insulin and adiponectin measurements via several commercial assays. Methods: Endogenous lipemia was evaluated using plasma and serum samples with triglyceride concentrations of 1000 mg/dL (n = 6 each). Sample insulin concentrations were determined via fluorescence enzyme immunoassay (FEIA), ELISA, and lateral flow assay (LFA). ...
Blood and fecal metabolic responses of mature horses fed rhizoma peanut hay. Rhizoma peanut (RP, Arachis glabrata Benth) is an alternative legume forage to alfalfa (ALF, Medicago sativa L.) with less non-structural carbohydrates and crude protein. Yet, metabolic responses to consuming RP hay have never been evaluated in horses. Objective: The objective of this study was to investigate the effect of feeding RP 'Florigraze' hay on fecal and blood metabolic variables compared to alfalfa 'Legendary XHD' and bermudagrass (BMG, Cynodon dactylon L. 'Coastal') hays fed to maintenance horses. Methods: Six mature Quarter Horse geldings (596±40 kg) were randomly assigned to one ...
Differential profiles of GH, IGF-1, and fructosamine in follicular fluid and plasma of cyclic mares. Growth hormone (GH) influences follicular development mainly by stimulating insulin-like growth factor 1 (IGF-1), which acts systemically and locally within the ovary. However, the metabolic profile of follicular fluid (FF) in mares, particularly markers such as fructosamine (FRUCT), an indicator of glucose metabolism, remains poorly characterized. This study aimed to evaluate GH, IGF-1, and FRUCT concentrations in plasma and FF and their variation across follicle sizes. Sixty ovaries were collected during the breeding season from 30 clinically normal mares raised for meat production. Blood sa...
Effects of intravenous oxytocin on plasma serotonin and trainability in horses. Oxytocin (OXT) plays a crucial role in regulating the serotonin (5-HT) system and behavior. Although previous studies have reported significant relationships among OXT, 5-HT, and behavioral responses, the effects of OXT on 5-HT concentrations and behavioral traits in horses remain poorly understood. This study aimed to investigate the effects of intravenous OXT administration on plasma 5-HT concentrations and trainability in horses. A crossover design was employed using eight horses, each receiving either a 10-IU intravenous dose of OXT or normal saline. Blood samples were collected at baselin...
Comparative Analysis of Extracellular Vesicle Isolation From Equine Serum and Plasma Using Two Isolation Methods With Structural and Proteomic Validation. Extracellular vesicles (EVs) are promising biomarkers and mediators of intercellular communication, but their isolation from equine biofluids remains challenging. This study compared two isolation workflows-size-exclusion chromatography (SEC) and differential ultracentrifugation followed by SEC (UC + SEC)-to evaluate their efficiency, reproducibility, and the proteomic composition of EVs derived from equine serum and plasma. Blood from six healthy horses was processed to obtain platelet-free plasma and serum. EVs were isolated using SEC or UC + SEC and characterized by transmission ele...
