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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.
Effects of dietary flaxseed oil supplementation on equine plasma fatty acid concentrations and whole blood platelet aggregation. An 18-week feeding trial was performed to investigate the effects of an omega-3 (n-3) fatty acid-enriched ration on plasma fatty acid concentrations and platelet aggregation in healthy horses. Flaxseed oil served as the source of the n-3 fatty acid alpha-linolenic acid (ALA). Twelve horses were fed dietary maintenance requirements using a complete pelleted ration (80%) and timothy grass hay (20%) for a 2-week acclimation period before being randomly assigned either to a treatment (group 1) or control (group 2) group. Group 2 horses (n = 6) were fed the diet described in the acclimation period,...
Inactivation of West-Nile virus during peptic cleavage of horse plasma IgG. Peptic cleavage of horse plasma IgG is a common procedure for the preparation of F(ab)(2) products for human use, such as antivenin and antitoxin. The removal of the Fc fragment from the IgG molecule by enzymatic cleavage at low pH, ensures fewer side-effects of the F(ab)(2) product for passive immunotherapy compared with the whole IgG molecule. Since the starting material may be contaminated by zoonotic horse viruses, it is necessary to demonstrate the removal or inactivation of possible viral contaminants. Guidelines for performing such studies were published by the Commission for Plasma-Der...
Determination of the chondroitin sulfate disaccharides in dog and horse plasma by HPLC using chondroitinase digestion, precolumn derivatization, and fluorescence detection. A sensitive and selective HPLC method for the determination of the disaccharides of chondroitin sulfate in horse and dog plasma was validated. Chondroitin sulfate is degraded by chondroitinase ABC to three primary unsaturated disaccharides, (1) 2-acetamido-2-deoxy-3-O-(beta-D-gluco-4-enepyranosyluronic acid)-D-galactose, (2) 2-acetamido-2-deoxy-3-O-(beta-D-gluco-4-enepyranosyluronic acid)-4-O-sulfo-D-galactose, and (3) 2-acetamido-2-deoxy-3-O-(beta-D-gluco-4-enepyranosyluronic acid)-6-O-sulfo-D-galactose, when treated with chondroitinase. Plasma samples (0.5 ml) were treated with 50 mU of chon...
Plasma and urine electrolyte and mineral concentrations in Thoroughbred horses with recurrent exertional rhabdomyolysis after consumption of diets varying in cation-anion balance. To determine whether plasma, urine, and fecal electrolyte and mineral concentrations differ between clinically normal horses and Thoroughbreds with recurrent exertional rhabdomyolysis (RER) after consumption of diets varying in cation-anion balance. Methods: 5 Thoroughbred mares with RER and 6 clinically normal mixed-breed mares. Methods: Each of 3 isocaloric diets designated as low, medium, and high on the basis of dietary cation-anion balance (DCAB) values of 85, 190, and 380, respectively, were fed to horses for 14 days. During the last 72 hours, 3 horses with RER and 3 control horses had d...
Effect of withholding feed on concentration and composition of plasma very low density lipoprotein and serum nonesterified fatty acids in horses. To measure and compare the concentration and composition of very low-density lipoprotein (VLDL) in plasma and selected lipids in serum of horses fed mixed grass hay ad libitum or denied feed for 36 hours. Methods: 4 healthy adult mares. Methods: Mares were either fed mixed grass hay ad libitum or denied feed for 36 hours beginning at 8:00 AM. Blood samples were collected every 2 hours during the study period and analyzed for nonesterified fatty acid (NEFA), triglyceride (TG), VLDL, and glucose concentrations and composition of VLDL. Results: Withholding feed significantly increased mean serum ...
Changes in physiological parameters in overtrained Standardbred racehorses. Various changes in physiological parameters are associated with overtraining, which can be a serious problem for human and equine athletes. A 34 week longitudinal study was conducted to investigate the effects of an acute training overload on physiological parameters in 10 Standardbred racehorses. After 24 weeks of training, horses received 8 weeks of increased workload, followed by 2 weeks recovery. Horses performed a 2400 m time trial and a progressive submaximal exercise test on alternate weeks. By the end of the heavy training period, the average time for the final 1200 m of the time trial...
Pharmacokinetics of marbofloxacin in mature horses after single intravenous and intramuscular administration. The pharmacokinetic behaviour of marbofloxacin, a new fluoroquinolone antimicrobial agent developed exclusively for veterinary use, was studied in mature horses (n = 5) after single-dose i.v. and i.m. administrations of 2 mg/kg bwt. Drug concentrations in plasma were determined by high performance liquid chromatography (HPLC) and data obtained were subjected to compartmental and noncompartmental kinetic analysis. This compound presents a relatively high volume of distribution (V(SS) = 1.17 +/- 0.18 l/kg), which suggests good tissue penetration, and a total body clearance (Cl) of 0.19 +/- 0.042...
Pharmacokinetic/pharmacodynamic approach to assess irrelevant plasma or urine drug concentrations in postcompetition samples for drug control in the horse. The current performance of analytical techniques used for drug control in horses lead the Regulatory Authorities to decide whether trace levels of drugs legitimately used for therapeutic medication should or should not be reported. Here, we propose a well-ordered and nonexperimental pharmacokinetic/pharmacodynamic approach for the determination of irrelevant drug plasma (IPC) and urine concentrations (IUC). The published plasma clearance is used to transform an effective (marketed) dose into an effective concentration (EPC). EPC is transformed into an IPC by applying a safety factor (SF). This...
Indirect measurement of the production of plasma triacylglycerols by horses given a high-fat diet. The hypothesis tested was that the feeding of extra fat to horses would raise the production of plasma triacylglycerols (TAG). To measure TAG secretion, the indirect Triton method was used. Six adult horses were given a low-fat control or a high-fat diet according to a crossover design. In keeping with our earlier work, the high-fat diet lowered fasting plasma TAG concentrations by an average of 42% and raised post-heparin total lipoprotein lipase activity by 79%. The rate of increase in plasma TAG concentration after Triton administration was 49% lower when the horses were fed the high-fat di...
Pharmacokinetics of doramectin and ivermectin after oral administration in horses. A study was undertaken in order to compare plasma disposition kinetic parameters of doramectin (DRM) and ivermectin (IVM) in horses after oral administration. Ten crossbreed adult horses, clinically healthy, weighing 380-470 kg body weight (bw) were selected for study. Faecal examinations were performed to determine faecal parasite egg counts. Horses were allocated to two groups of five animals to provide an even distribution considering the variables sex, body weight and faecal egg count. Group I, were treated with an oral paste formulation of IVM at 0.2 mg/kg b/w and Group II, were treated w...
Plasma trypsin level in horses suffering from acute intestinal obstruction. Gastrointestinal disorders in horses leading to endotoxic shock could have further consequences on other splanchnic organs such as the pancreas, as can be seen in humans suffering from septic shock. In this study, the range of enzymatically active trypsin (EAT) in healthy horses was established and is similar to the range observed in healthy humans. EAT values were determined in horses with acute abdominal crises on admission as well as during anaesthesia and in the postoperative phase. A significant increase in plasma EAT was found in 59% of the horses with surgical colic when compared to our...
Pharmacokinetics of erythromycin ethylsuccinate after intragastric administration to healthy foals. Plasma concentrations and pharmacokinetics of erythromycin and related compounds were determined after administration of erythromycin ethylsuccinate to six healthy male foals 3 to 5 months of age. Hay was withheld from the foals overnight and erythromycin ethylsuccinate (25 mg/kg of body weight) was administered intragastrically. Plasma erythromycin concentrations were determined at specific times after drug administration by high-performance liquid chromatography assay. Maximum peak plasma concentrations, time to maximum concentrations, area under plasma concentration versus time curves, elim...
Hematology of equine fetuses with comparisons to their dams. The Hematologic values of 19 equine fetuses between 202 and 238 days gestation were compared with those of their dams. The red blood cell (RBC) count, hemoglobin concentration, hematocrit, and mean corpuscular hemoglobin concentration were significantly lower in fetal blood, while the mean corpuscular volume, mean corpuscular hemoglobin, and red cell distribution width were significantly higher. Mares had a significantly higher nucleated blood cell count than fetuses, and all nucleated cells were leukocytes (WBC). Most WBC in mare blood were segmented neutrophils and lymphocytes. In contrast, ...
The concentration of plasma triacylglycerols in horses fed diets containing either medium chain triacylglycerols or an isoenergetic amount of starch or cellulose. In a Latin square design, six horses were fed hay and concentrates with isoenergetic amounts of either starch, cellulose or medium chain triacylglycerols (MCT). The dietary variables provided on average 22% of total dietary net energy. Plasma triacylglycerols and other variables of lipid metabolism were determined. The experimental periods lasted 21 days. Blood samples were taken just before the morning meal and three and six hours later. The diet rich in MCT significantly raised the plasma level of triacylglycerols when compared to either the starch- or cellulose-rich diet. The plasma concent...
Comparison of pharmacokinetic variables for two low-molecular-weight heparins after subcutaneous administration of a single dose to horses. To determine pharmacokinetic variables and to evaluate the influence on clotting times after SC administration of single doses of dalteparin and enoxaparin to horses. Methods: 5 healthy adult horses. Methods: The study was designed as a 4-period crossover study. Each horse received a single SC injection of dalteparin (50 and 100 anti-Xa U/kg) and enoxaparin (40 and 80 anti-Xa U/kg). Plasma anti-Xa activities and clotting times were measured, and pharmacokinetic variables were determined. Absolute and relative maximal prolongation of clotting times was calculated, and correlation between plasma...
Lipoic acid as an antioxidant in mature thoroughbred geldings: a preliminary study. alpha-Lipoic acid (LA) has demonstrated antioxidant effects in humans and laboratory animals. The objective of this study was to determine whether the effects of LA are similar in horses. Five Thoroughbred geldings were supplemented with 10 mg/kg/d DL-alpha-lipoic acid in a molasses and sweet feed carrier and five received only the carrier as a placebo (CON). Blood samples were obtained at baseline (0 d), after 7 and 14 d of supplementation, and 48 h postsupplementation (16 d). Blood fractions of red and white blood cells (RBC and WBC, respectively) and plasma were analyzed for glutathione (GS...
Changes in circulatory antioxidant status in horses during prolonged exercise. Prolonged low-medium intensity exercise is associated with increased oxidative stress in humans. We hypothesized that competitive equine endurance racing would induce changes in circulatory antioxidants and produce systemic oxidative stress. Forty horses competing in a 140-km endurance race in warm conditions [shade temperature 15-19 degrees C; 62-88% relative humidity (%RH)] were sampled before (Pre), immediately after exercise (End) and at approximately 16 h into recovery (+16 h). Plasma ascorbic acid concentration was not different between Pre [11.1 (median); 4.6-20.3 micromol/L (range)] an...
Biochemical and antioxidant changes in plasma and erythrocytes of pentathlon horses before and after exercise. Physical exercise in the horse induces a series of normal physiological and biochemical adaptations. Increasing metabolism and oxygen uptake may induce oxidative stress in various organs. The aim of this study was to examine exercise-induced changes in some plasma and RBC biochemical and antioxidant variables in pentathlon horses. Blood samples were taken from 14 horses before, immediately after, and 24 hours after competing in two 1-minute runs of intense exercise over jumps. The peak intensity periods were preceded by a 20-minute warm-up and separated by a 20-minute break. The following plas...
Plasma disposition, faecal excretion and in vitro metabolism of oxibendazole following oral administration in horses. Oxibendazole (OBZ) was administered to eight horses at an oral dose of 10 mg kg(-1) bodyweight each. Parent OBZ could only be detected in plasma at the 0.5 and 1.0 hours post administration sampling times and the mean maximum plasma concentration was 0.008 microg ml(-1). Parent OBZ was detected in faeces between 12 and 72 hours after administration and the highest dry faecal concentration was detected at 24 hours. An unidentified metabolite was detected in plasma between 0.5 and 72 hours. The unidentified metabolite in the plasma of treated horses corresponded to the second eluted metabolite i...
Administration of sulpiride to anovulatory mares in winter: effects on prolactin and gonadotropin concentrations, ovarian activity, ovulation and hair shedding. Sixteen seasonally anovulatory mares were randomly allotted to two groups and injected daily with either sulpiride (1 mg/kg body weight) or vehicle from 14 January to 14 February. Sulpiride administration increased daily plasma prolactin concentrations (P < 0.05), although the prolactin response during the 6 h following sulpiride injections decreased markedly from the 1st to the 6th day of treatment (treatment by day, P 0.1). Injection of GnRH and TRH on 15 February showed that the response of plasma prolactin to secretagogue was increased in sulpiride-treated mares (P 0.1) of sulpiride t...
Pharmacokinetics of azithromycin in foals after i.v. and oral dose and disposition into phagocytes. The properties of azithromycin suggest that it may be an alternative to erythromycin for treatment of Rhodococcus equi pneumonia in foals. To investigate this possibility, the disposition of azithromycin in plasma, polymorphonuclear leukocytes (PMN), and alveolar cells was examined after a single administration in foals. Azithromycin suspension was administered orally (p.o.) at a dose of 10 mg/kg to five healthy 2-3-month-old foals. Two weeks later, azithromycin for injection was administered by intravenous (i.v.) infusion at a dose of 5 mg/kg to the same foals. Plasma samples were collected a...
Study of the plasma pharmacokinetics and faecal excretion of the prodrug olsalazine and its metabolites after oral administration to horses. Olsalazine sodium (Dipentum*) has been used therapeutically against inflammatory bowel disease in human medicine as an alternative to sulphasalazine over the past 20 years. Bacteria in the colon split this prodrug into two molecules of the locally effective 5-aminosalicylic acid (5-ASA). Considering the potential therapeutic use in equine colitis, the pharmacokinetics of olsalazine (OLZ) after single oral administration to six horses at a dosage of 30 mg/kg was investigated. Plasma concentrations of OLZ, 5-ASA, and its main metabolite N-acetyl-5-aminosalicylic acid (Ac-5-ASA) were analysed by ...
Isoxsuprine hydrochloride in the horse: a review. Isoxsuprine hydrochloride has been suggested for use in horses for treatment of navicular syndrome and laminitis. The drug has been shown to be a beta-adrenoreceptor antagonist with beta-adrenoreceptor agonistic properties, with both characteristics contributing to vasodilation and uterine relaxation. In addition, the drug is capable of decreasing blood viscosity and platelet aggregation. Studies have shown i.v. isoxsuprine to have a plasma half-life of <3 h with a large apparent volume of distribution. Cardiovascular effects resolve rapidly following i.v. administration, but are absent wit...
The plasma level of triacylglycerols in horses fed high-fat diets containing either soybean oil or palm oil. The influence of dietary soybean oil versus palm oil on the plasma level of triacylglycerols was determined in a crossover experiment with four horses. Based on published data for humans and laboratory animals it was expected that a diet rich in unsaturated fatty acids in the form of soybean oil compared to saturated fatty acids in the form of palm oil would lower the plasma triacylglycerol level. The feeding of soybean oil versus palm oil for a period of four weeks did not change the level of plasma triacylglycerols in horses. Mean levels of triacylglycerol, free fatty acids and 3-hydroxybuty...
Effects of racing on lymphocyte proliferation in horses. To measure the lymphocyte proliferation response in horses 12 to 16 hours after completion of a race. Methods: 8 Thoroughbreds that competed in 14 races and 3 control Thoroughbreds that did not race. Methods: Horses participated in races during the late afternoon or evening. Venous blood samples were collected on a morning before a race (1 or 2 days before the race or on the day of the race), on the afternoon of a race (40 to 60 minutes after the race), and on the morning of the day after a race (12 to 16 hours after the race). Lymphocyte proliferation responses and WBC count were measured in ...
Effects of frequency of treatment with recombinant equine somatotropin on selected biological responses in geldings. Two experiments compared the efficacies of different treatment frequencies for recombinant equine somatotropin (eST). In Experiment 1, five geldings received daily injections of eST at 20 microg/kg of body weight, and five received every-other-day injections at 40 microg/kg of body weight, for a total of 30 days. Plasma glucose (P=0.0001), insulin (P=0.0135), and non-esterified fatty acid (NEFA, P=0.0001) concentrations increased, and plasma urea nitrogen (PUN) concentrations decreased (P=0.0001), in both groups, and only minor differences (P<0.05) occurred between the two groups. Insulin-l...
Detection of morphine in blood and urine samples from horses administered poppy seeds and morphine sulfate orally. The objective of this study was to determine if the administration of poppy seeds to horses would result in detectable concentrations of morphine in urine and blood samples, as has been shown to occur in humans. In this study blood and urine samples were collected following administration of poppy seeds and morphine sulfate orally to four horses. Urine samples were subjected to enzyme-linked immunosorbent assay (ELISA) for the presence of morphine. All urine samples testing positive by ELISA, as well as plasma samples collected after administration of the 10-g doses of poppy seeds, were analyz...
Plasma concentrations of endothelin-like immunoreactivity in healthy horses and horses with naturally acquired gastrointestinal tract disorders. To compare plasma endothelin (ET)- like immunoreactivity between healthy horses and those with naturally acquired gastrointestinal tract disorders. Methods: 29 healthy horses and 142 horses with gastrointestinal tract disorders. Methods: Blood samples were collected from healthy horses and from horses with gastrointestinal tract disorders prior to treatment. Magnitude and duration of abnormal clinical signs were recorded, and clinical variables were assessed via thorough physical examinations. Plasma concentrations of ET-like immunoreactivity were measured by use of a radioimmunoassay for huma...
Effectiveness of a two-dose regimen of prostaglandin administration in inducing luteolysis without adverse side effects in mares. Our objectives were to determine whether repeated administration of prostaglandin F2alpha (PGF2alpha) to simulate the endogenous mode of secretion would be more effective than a single injection in inducing luteolysis and enable use of smaller doses less likely to cause adverse side effects. The main study comprised 43 dioestrous mares, who were given im. either a single 10 mg dose of natural PGF2alpha (n = 22) or 2 doses of 0.5 mg PGF2, 24 h apart (n = 21). The intensity of side effects was assessed in 8 dioestrous mares given 5, 1.5, 0.5 or 0 mg PGF2alpha in consecutive cycles. Two doses of ...
Water intake and fluid shifts in horses: effects of hydration status during two exercise tests. In the present study, the main objective was to study factors affecting postexercise voluntary water intake in horses. Four Standardbred horses (mean +/- s.e. bwt 500 +/- 8 kg) were used to study water intake and effects of altering hydration status before an incremental exercise test (INCR) and a 40 min constant velocity exercise test (CONST) on a treadmill. Exercise was performed during normohydration (N), after dehydration for 24 h (DEH) and after hyperhydration with 12 l water 30 min before exercise (HH). DEH resulted in a bodyweight loss of 3% and there were signs of some fluid uptake pri...
