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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.
Pharmacokinetics of voriconazole following intravenous and oral administration and body fluid concentrations of voriconazole following repeated oral administration in horses. To determine the pharmacokinetics of voriconazole following IV and PO administration and assess the distribution of voriconazole into body fluids following repeated PO administration in horses. Methods: 6 clinically normal adult horses. Methods: All horses received voriconazole (10 mg/kg) IV and PO (2-week interval between treatments). Plasma voriconazole concentrations were determined prior to and at intervals following administration. Subsequently, voriconazole was administered PO (3 mg/kg) twice daily for 10 days to all horses; plasma, synovial fluid, CSF, urine, and preocular tear film con...
Determination of glucosamine in horse plasma by liquid chromatography tandem mass spectrometry. Glucosamine is an amino sugar involved in the biosynthesis of glycosylated proteins and lipids. Recently, with increased public interest in natural products medicine, glucosamine has been widely used to treat osteoarthritis, even though demonstrations of its actual efficacy remain relatively unknown. Information related to the pharmcokinetics of glucosamine is sparse. A recent analytical method published used 13C-glucosamine as an internal standard to analyse study samples. The method lacked accuracy owing to an important natural isotopic contribution of glucosamine to 13C-glucosamine ion abun...
Short-term effects of energy changes on plasma leptin concentrations and glucose tolerance in healthy ponies. To determine whether plasma leptin concentrations and glucose tolerance are affected by changes in energy balance, nine healthy Shetland ponies were fed at 140% followed by 75% of their maintenance requirements for 13 days in each of the two periods. Bodyweight was recorded every three days. Blood samples were taken every two days and analysed for leptin and cortisol. An oral glucose tolerance test was performed on day 7 of each period. Serial blood samples were analysed for glucose and insulin. Although bodyweight was not affected, plasma leptin concentrations increased (P<0.001) initially...
Pharmacokinetics of acyclovir after intravenous infusion of acyclovir and after oral administration of acyclovir and its prodrug valacyclovir in healthy adult horses. The purpose of this study was twofold. The first aim was to evaluate the oral bioavailability and pharmacokinetics (PKs) of acyclovir in horses after intravenous (i.v.) administration and after oral administration of acyclovir and its prodrug, valacyclovir. Second, we aimed to combine these PK data with pharmacodynamic (PD) information, i.e., 50% effective concentrations (EC(50) values) from in vitro studies, to design an optimal dosage schedule. Three treatments were administered to healthy adult horses: 10 mg of acyclovir/kg of body weight delivered as an i.v. infusion over 1 h, 20 mg of acy...
Evaluation of a turbidimetric immunoassay for measurement of plasma IgG concentration in foals. To validate a turbidimetric immunoassay (TIA) for measurement of plasma IgG concentrations in foals. Methods: 36 foals. Methods: Blood samples were collected from foals before suckling and at 12 and 24 to 36 hours after birth. Plasma IgG concentrations were determined via a commercial single radial immunodiffusion (RID) assay. By use of goat anti-equine IgG antiserum and a spectrophotometer, a TIA was developed to measure plasma and serum IgG concentrations; the percentage light transmission was calibrated against RID assay-determined IgG concentrations. Assay repeatability and effects of seri...
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...
Plasma colloid osmotic pressure and total protein in horses during colic surgery. To assess the changes in colloid osmotic pressure (COP) in horses undergoing surgery for colic. Methods: Prospective clinical evaluation. Methods: Twenty-nine adult horses presented for emergency laparotomy. Methods: Horses were premedicated with intravenous (IV) xylazine and anesthesia was induced with ketamine, diazepam and guaifenesin and was maintained with isoflurane as required. Lactated Ringer's solution (LRS) was given to all horses during anesthesia. Blood was collected in heparin before, and every 30 minutes during, anesthesia to measure COP, total protein concentration (TP), osmolal...
Plasma lactate as a predictor of colonic viability and survival after 360 degrees volvulus of the ascending colon in horses. To determine the relationship between plasma lactate concentration and colonic viability and survival in horses with >or=360 degrees volvulus of the ascending colon. Methods: Retrospective study. Methods: Horses (n=73) with >or=360 degrees volvulus of the ascending colon. Methods: Medical records (January 2000-November 2005) of all horses examined for colic at Michigan State University Veterinary Teaching Hospital were reviewed. Horses were included only if plasma lactate concentration was measured preoperatively and a diagnosis of >or=360 degrees volvulus of the ascending colon was c...
Influence of age and foaling on plasma protein electrophoresis and serum amyloid A and their possible role as markers of equine neonatal septicaemia. A field study was undertaken to investigate plasma protein electrophoresis (PPE) and serum amyloid A (SAA) concentrations at 1, 3 and 7 days of age in foals born by oxytocin-induced (group A, n =17) or spontaneous (group B, n =12) parturition. The putative diagnostic role of PPE and SAA in four septicaemic foals was also examined. At birth, beta-gamma-globulins were higher in group B, and then increased in both groups, probably due to colostrum intake. At day 3, no significant differences between the groups were detectable. In both groups, SAA values increased from day 0 to day 3, then decreas...
Pharmacokinetic studies on tobramycin in horses. The objective of the study was to evaluate the pharmacokinetics of tobramycin in plasma and urine in the horse (n = 7) after intravenous administration of a dose of 4 mg/kg b.w. Plasma tobramycin concentrations were assayed microbiologically and by means of HPLC analyses. Pharmacokinetic parameters, calculated on the basis of concentrations determined with the microbiological assay were not statistically different from those obtained when data from HPLC analysis were used, but the microbiological assay was more sensitive in the detection of low plasma and urine values. The values of the total ...
Stereoselective pharmacokinetics of ketamine and norketamine after racemic ketamine or S-ketamine administration in Shetland ponies sedated with xylazine. The pharmacokinetics of ketamine and norketamine enantiomers after administration of intravenous (IV) racemic ketamine (R-/S-ketamine; 2.2 mg/kg) or S-ketamine (1.1 mg/kg) to five ponies sedated with IV xylazine (1.1mg/kg) were compared. The time intervals to assume sternal and standing positions were recorded. Arterial blood samples were collected before and 1, 2, 4, 6, 8 and 13 min after ketamine administration. Arterial blood gases were evaluated 5 min after ketamine injection. Plasma concentrations of ketamine and norketamine enantiomers were determined by capillary electrophoresis and wer...
Enantioselective analysis of ketamine and its metabolites in equine plasma and urine by CE with multiple isomer sulfated beta-CD. CE with multiple isomer sulfated beta-CD as the chiral selector was assessed for the simultaneous analysis of the enantiomers of ketamine and metabolites in extracts of equine plasma and urine. Different lots of the commercial chiral selector provided significant changes in enantiomeric ketamine separability, a fact that can be related to the manufacturing variability. A mixture of two lots was found to provide high-resolution separations and interference-free detection of the enantiomers of ketamine, norketamine, dehydronorketamine, and an incompletely identified hydroxylated metabolite of no...
Dietary fructan carbohydrate increases amine production in the equine large intestine: implications for pasture-associated laminitis. Pasture-induced laminitis in the horse is associated with the overconsumption of fermentable carbohydrate, in the form of simple sugars, fructans, or starch. The fermentation of carbohydrate in the cecum and large intestine results in the production of lactic acid and other toxins or "laminitis trigger factors." Vasoactive amines have been suggested as possible initiating factors. The aim of this study was to feed a commercially available form of fructan carbohydrate (inulin, 3 g/kg of BW per day) to normal ponies and to ponies predisposed to laminitis, to mimic a change from a basal hay diet ...
Serum iron and plasma fibrinogen concentrations as indicators of systemic inflammatory diseases in horses. Detection of systemic inflammation, which is important for proper diagnosis and prompt treatment, can be challenging. Objective: Measurement of plasma iron concentration is a sensitive method for detecting systemic inflammation in horses compared with measurements of plasma fibrinogen concentration, a traditional marker for inflammation in the horse. Methods: Ninety-seven horses hospitalized with diseases causing systemic inflammation, 22 horses with localized inflammation, and 12 clinically normal horses were included in this study. Methods: A retrospective study was made on hospitalized hors...
Exercise-induced alterations in pro-inflammatory cytokines and prostaglandin F2alpha in horses. Using an established standardized exercise test on a high-speed treadmill, thirteen Thoroughbred racehorses were exercised to fatigue (failure); blood samples were obtained before exercise, at failure, and at 2, 6, 24, 48, and 72 h after exercise. The exercise test induced a systemic inflammatory response characterized by a mild transient endotoxemia, leukocytosis, increased leukocyte expression of mRNA for tumor necrosis factor-alpha (TNF-alpha), IL-1 beta, and IL-6, and increased circulating concentrations of TNF-alpha and prostaglandin F2 alpha (PGF 2 alpha), with the most pronounced change...
The quantitation of procaine in equine plasma by liquid chromatography-linear ion trap mass spectrometry. A method for the extraction and quantitation of procaine in equine plasma was developed for use with liquid chromatography-mass spectrometry (LC-MS). Procaine was isolated from equine plasma by liquid-liquid extraction at pH 11 with dichloromethane using procaine-d10 as an internal standard. Quantitation was achieved by LC-MS using a 3-microm C-18 column coupled to an electrospray ionization source on a linear ion-trap mass spectrometer. The limit of detection and limit of quantitation was determined to be 50 and 200 pg/mL, respectively. The lowest limit of detection determined by previous met...
Postmortem diagnosis of idiopathic hyperammonemia in a horse. A 6-year-old Quarter Horse stallion was referred to Oklahoma State University Veterinary Medical Teaching Hospital for evaluation of abdominal pain that developed after breeding activity earlier in the day. The horse developed diarrhea and progressively worsening neurologic signs (circling, ataxia, head pressing) within 22 hours of presentation and was subsequently euthanized due to severe self-destructive behavior. Antemortem biochemical and hematologic abnormalities included hypocalcemia but no evidence of hepatic disease. Idiopathic hyperammonemia and encephalopathy were suspected; cerebros...
Glycaemic and insulinaemic responses to mechanical or thermal processed barley in horses. This study was conducted to evaluate the effects of different barley processing techniques on the glycaemic and insulinaemic responses in horses. It was hypothesized that the changes in pre-caecal starch digestibility caused by barley processing would affect metabolic responses. Six horses were fed in random order: whole (WB), finely ground (FGB), steamed (SB), steam-flaked (SFB) and popped barley (PB). The total barley intake was adjusted to 630 g starch/horse/day (1.2-1.5 g starch/kg BW/day). During a 10-day stabilization period, the horses also received 6 kg grass hay/horse/day. On the bloo...
LC-MS/MS method for confirmation of recombinant human erythropoietin and darbepoetin alpha in equine plasma. Recombinant human erythropoietin (rhEPO) and darbepoetin alpha (DPO) are protein-based drugs for the treatment of anemia by stimulating red blood cell production. Consequently, they are abused in human and equine sports. To deter their abuse in the horse racing industry, a sensitive and reliable method for confirmation of these agents in equine plasma has been in urgent need. Such a method by LC-MS/MS is described in this paper. The method involved analyte enrichment by immunoaffinity separation using anti-rhEPO antibody linked to magnetic beads, digestion by trypsin, and analysis by LC-MS/MS....
Quantitative HPLC-UV method for the determination of firocoxib from horse and dog plasma. A sensitive reversed-phase HPLC-UV method was developed for the determination of firocoxib, a novel and highly selective COX-2 inhibitor, in plasma. A 1.0 mL dog or horse plasma sample is mixed with water and passed through a hydrophobic-lipophilic copolymer solid-phase extraction column to isolate firocoxib. Quantitation is based on an external standard curve. The method has a validated limit of quantitation of 25 ng/mL and a limit of detection of 10 ng/mL. The validated upper limit of quantitation was 2500 ng/mL for horses and 10,000 ng/mL for dogs. The average recoveries ranged from 88-93% ...
Clinical signs and etiology of adverse reactions to procaine benzylpenicillin and sodium/potassium benzylpenicillin in horses. Case reports of 59 horses reacting adversely to procaine benzylpenicillin or to sodium or potassium benzylpenicillin in Sweden in 2003-2005 were obtained through contacts with horse-owners. For the assessment of the reports, various parameters were evaluated, such as the times to the reactions, information on previous penicillin treatment, the clinical signs and the actions taken in the reacting horses. Among the reports, two horses had received sodium or potassium benzylpenicillin intravenously, whereas the remaining 57 horses had been treated with procaine benzylpenicillin intramuscularly. A...
Cetirizine in horses: pharmacokinetics and effect of ivermectin pretreatment. The pharmacokinetics of the histamine H(1)-antagonist cetirizine and the effects of pretreatment with the antiparasitic macrocyclic lactone ivermectin on the pharmacokinetics of cetirizine were studied in horses. After oral administration of cetirizine at 0.2 mg/kg bw, the mean terminal half-life was 3.4 h (range 2.9-3.7 h) and the maximal plasma concentration 132 ng/mL (101-196 ng/mL). The time to reach maximal plasma concentration was 0.7 h (0.5-0.8 h). Ivermectin (0.2 mg/kg bw) given orally 1.5 h before cetirizine did not affect its pharmacokinetics. However, ivermectin pretreatment 12 h be...
Plasma colloid osmotic pressure and total protein trends in horses during anesthesia. To investigate the changes in colloid osmotic pressure (COP) and total protein concentrations during routine general anesthesia in horses. Methods: Prospective, clinical study. Methods: Twelve adult healthy horses aged 9.1 +/- 4.7 years and weighing 474 +/- 79 kg presented for elective surgery and 14 adult horses aged 8.7 +/- 7.3 years and weighing 510 +/- 85 kg. Methods: All horses were premedicated with xylazine and anesthesia induced with ketamine, diazepam and guaifenesin, and maintained with isoflurane for 2.5 hours. Lactate Ringer's solution was administered at 11 mL kg(-1) hour(-1). Osm...
Determination of lactate concentrations in blood plasma and peritoneal fluid in horses with colic by an Accusport analyzer. Intestinal hypoperfusion can lead to increased lactate concentrations in plasma and peritoneal fluid of horses with colic. Objective: The purposes of this study were to (1) evaluate the reliability of the Accusport analyzer to assess peritoneal fluid lactate (PFL) concentrations in healthy horses and those with colic, (2) identify clinical features associated with abnormal blood plasma lactate (BPL) and PFL concentrations, and (3) evaluate the prognostic value of BPL and PFL. Methods: BPL and PFL were determined in 20 healthy horses and in 106 horses with colic. Results: The Accusport was reli...
Automated liquid chromatography-tandem mass spectrometry method for the analysis of firocoxib in urine and plasma from horse and dog. A rugged, sensitive and efficient liquid chromatography-tandem mass spectrometry method was developed and validated for the quantitative analysis of firocoxib in urine from 5 to 3000 ng/mL and in plasma from 1 to 3000 ng/mL. The method requires 200 microL of either plasma or urine and includes sample preparation in 96-well solid phase extraction (SPE) plates using a BIOMEK 2000 Laboratory Automated Workstation. Chromatographic separation of firocoxib from matrix interferences was achieved using isocratic reversed phase chromatography on a PHENOMENEX LUNA Phenyl-Hexyl column. The mobile phase w...
A direct enzyme immunoassay for the measurement of furosemide in horse plasma. A new enzyme immunoassay (EIA) for the measurement of furosemide in horse plasma is described. The lower limit of detection of this EIA method was 7.8 ng/ml. The intra-and inter-assay coefficients of variation ranged from 2.5% to 4.9% and 7.5% to 9.8%, respectively. Cross-reactivity with other compounds was not observed. There was a high correlation (r2=0.987) between the high-performance liquid chromatography and EIA results obtained for furosemide concentrations in horse plasma. These results indicate that the newly developed EIA method is useful for the quantitative analysis of furosemide i...
Effects of different levels of calcium and phosphorus intake on calcium homeostasis in exercising horses. Increasing levels of dietary calcium (Ca) and phosphorous (P) might have a negative impact on parathyroid hormone (PTH) response and result in a more pronounced hypocalcaemia during high-speed exercise in horses. Methods: In successive order, five trained horses were fed 33 g Ca and 19 g P (approximately 100% NRC, adequate intake), 64 g Ca and 38 g P (moderately high intake) or 96 g Ca and 56 g P (high intake). Each horse was adapted to each diet over a 21 day period before undergoing a standardised exercise test (SET) on a treadmill. The SET comprised 5 steps (each step 4 min duration, 3% inc...
Low dose exogenous erythropoietin elicits an ergogenic effect in standardbred horses. Recombinant human erythropoietin (rhuEPO) causes an increase in red blood cell production and aerobic capacity in other species; however, data are lacking on effects in the horse. Objective: This study tested the hypothesis that rhuEPO administration would alter red cell volume (RCV), aerobic capacity (VO2max) and indices of anaerobic power. Methods: Eight healthy, unfit mares accustomed to the laboratory and experimental protocols were randomly assigned to either a control (CON, n = 4; 3 ml saline 3 times/week for 3 weeks) or EPO group (EPO, n = 4, 50 iu/kg bwt rhuEPO/3 ml saline 3 times/week...
Changes in arterial, mixed venous and intraerythrocytic concentrations of ions in supramaximally exercising horses. Horses experience major perturbations in acid-base balance during supramaximal exercise. Ion movement in and out of erythrocytes (RBCs) is believed to be important in maintaining acid-base balance but it is unclear as to the extent to which this happens, nor how it affects single measurements of ion concentrations in arterial and venous blood. Objective: To clarify the role RBCs play in mitigating perturbations in acid-base balance during high speed exercise in horses, and to describe associated differences in arterial (a) and mixed venous (v) concentrations of key ions. Methods: Six exercise-...
Plasma glutamine concentrations in the horse following feeding and oral glutamine supplementation. Pharmacological benefits of glutamine supplementation have been shown in athletically and clinically stressed human subjects. In the horse, infection and intense exercise have also been shown to significantly decrease plasma glutamine concentrations, but little is known on how best to supplement. Objective: To evaluate whether ingestion of different foodstuffs, with or without L-glutamine (G) or a peptide (Pep) containing 31.5% w/w G in a water-stable form, could affect plasma glutamine concentrations (P-GC). Methods: Nine feeds (molassed sugar beet-pulp (mSB); naked oats (nO); commercial mix ...
