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.
Rubio MD, Muñoz A, Santisteban R, Tovar P, Castejón FM.Exercise-induced hematological alterations were studied in 20 four-year old foals, 11 Andalusian and 9 Arabian. They were subjected to a test exercise program consisting of 4 levels of gradually increasing intensity (15, 20, 25 and 30 km/hr) with a duration of 5 min each. Blood samples were taken during resting, after each exercise level and at 10 and 30 min of recovery from exercise. The following hematic parameters were analyzed: red blood count, hematocrit value, hemoglobin, volumetric indexes (MCV, MCH and MHCH) and total plasma proteins. The alterations as a result of the physical effort ...
Soraci A, Benoit E, Jaussaud P, Lees P, Delatour P.Carprofen (CPF) enantiomers and their glucuronide conjugates (GLUC) were measured in plasma and bile of horses after IV administration of the racemic compound (0.7 mg/kg of body weight). The CPF was detectable in plasma for up to 72 hours after dosing, whereas GLUC appeared early (time for maximal plasma concentration, 1 hour) and was measurable transiently at low concentration (maximal plasma concentration, 0.5 microgram/ml). The enantiospecific plasma profiles indicated a clear predominance of R-CPF, whereas the stereoselectivity of the glucuronides favored S-GLUC. At 1, 2, and 12 hours afte...
Causey RC, Paccamonti DL, Todd WJ.A total of 22 clinical streptococcal isolates, predominantly Streptococcus zooepidemicus, associated with endometritis in horses were tested for their ability to withstand the natural bactericidal properties of freshly obtained blood. During a 3-hour incubation in blood from a single horse, 8 of these isolates survived and grew, the remainder were killed. To determine whether this ability to grow extended to blood of other horses, 5 of these growing isolates were tested for their ability to grow in the blood of 5 additional horses. The same 5 horses were used for each isolate. The isolates gre...
van Duijkeren E, Vulto AG, Sloet van Oldruitenborgh-Oosterbaan MM, Kessels BG, van Miert AS, Breukink HJ.In the present study, the pharmacokinetic parameters of a trimethoprim/sulphachlorpyridazine preparation following intravenous administration, administration by nasogastric tube and administration with concentrate were determined in the horse. Eight adult horses were dosed at 1 week intervals in a sequentially designed study at a dose of 5 mg/kg trimethoprim (TMP) and 25 mg/kg sulphachlorpyridazine (SCP) on all occasions. Plasma concentrations of both drugs were measured serially for 48 h. Pharmacokinetic parameters of clinical importance (distribution and elimination half-lives, clearance, bi...
Fey K, Klatt P, Schmidt H, Sasse HH.Five healthy horses were given a sulfadoxine/trimethoprim combination (Borgal, Hoechst AG) i.v. on day 1. The next ten days the horses got once a day a sulfadimethoxine/trimethoprim combination orally (Trafigal, Hoechst AG). The doses were given as recommended. One horse received no medicaments for control. On each horse six bronchoalveolar lavages were performed. Blood samples were taken to calculate blood levels and elimination half lives. To determine the amount of substances in lavage fluid and plasma the high performance liquid chromatography (HPLC) was used. Regularly low quantities of s...
Mitten LA, Hinchcliff KW, Pate JL, Kohn CW, McKeever KH.Exertion has an effect on plasma, serum, and/or urine prostanoid concentrations in many species. We investigated the effect of exercise intensity on plasma prostaglandin concentrations during and after exercise in horses. Six Thoroughbreds completed 4 trials: 3 exercise trials (low-, medium-, and high-speed) and 1 nonexercise (control) trial on a high-speed treadmill. Blood samples were collected from a jugular catheter before, during, and after exercise. The PCV and blood lactate, plasma protein, plasma prostacyclin (6-keto-PGF1 alpha), thromboxane B2 (TXB2), and prostaglandin E2 (PGE2) conce...
Rossdale PD, Ousey JC, McGladdery AJ, Prandi S, Holdstock N, Grainger L, Houghton E.Plasma progestagen concentrations were measured daily by radioimmunoassay (RIA) in 35 sick foals for the duration of their illness. The foals were divided into three groups on the basis of time to stand after birth. Foals were given intensive care treatment according to the severity of their illness. Plasma and urine concentrations of pregnenolone (P5) and pregnenediol (P5 beta beta) were measured by gas chromatography--mass spectrometry; plasma cortisol concentrations were measured by RIA and the foals' renal and respiratory status were assessed by creatinine clearance ratios and arterial oxy...
Sticker LS, Thompson DL, Bunting LD, Fernandez JM, DePew CL.Sixteen light horse mares (8 to 9 yr of age; 457 to 579 kg BW) were fed Bermudagrass hay and a corn/cottonseed hull-based supplement formulated to contain either 100% (control) or 50% (restricted) of the protein and(or) energy requirements for maintenance in a 2 x 2 factorial arrangement of treatments. Daily measurements of intake, BW, and plasma hormones and metabolites were made for 33 d. Plasma glucose, insulin, NEFA, and urea N were measured in hourly samples drawn on d 27, and parallel with an i.v. glucose tolerance test (IVGTT) and epinephrine challenge on d 29. Energy restriction increa...
Sandholm M, Vidovic A, Puotunen-Reinert A, Sankari S, Nyholm K, Rita H.The discriminating ability of 15 parameters alone or in combinations, including results from analysis of plasma endotoxin, the Nycomed plasma D-Dimer test and phospholipase A2, were analyzed to predict morbidity and mortality in equine gastrointestinal colic. Endotoxaemia was a characteristic feature of the colic horses. The problem of adequately predicting nonsurvivors among colic horses required several parameters to be included in the logistic model: if the "classical parameters", (heart rate, respiratory rate, PCV, anion gap) were included in the model, addition of plasma D-dimer, phosphol...
Collatos C, Barton MH, Moore JN.Plasma fibrinolytic activity was evaluated over 5 consecutive days in 59 horses admitted to the Large Animal Teaching Hospital with acute gastrointestinal diseases. Only horses hospitalized for at least 5 days were included in the study. Tissue plasminogen activator (tPA) and plasminogen activator inhibitor type-1 (PAI-1) were quantitated using standard chromogenic activity assays. Statistical analyses were performed using analysis of variance; differences were considered significant when P < or = .05. Activity of PAI-1, the primary endogenous inhibitor of fibrinolysis, was significantly incre...
Luna SP, Taylor PM.The effect of thiopentone/halothane anaesthesia on the release of endogenous opioid, adrenocorticotrophin, arginine vasopressin, cortisol and catecholamine was investigated in ponies. The contribution made by halothane itself was studied by maintaining six ponies with a constant 1.2 per cent end tidal halothane concentration and five with a concentration ranging between 0.8 and 1.2 per cent. Cardiorespiratory depression was more prolonged in the ponies receiving a constant 1.2 per cent end tidal halothane concentration than in those which received less halothane. Plasma lactate concentration i...
Crabb BS, MacPherson CM, Reubel GH, Browning GF, Studdert MJ, Drummer HE.We describe a type-specific ELISA, which distinguishes antibody to equine herpesvirus 4 (EHV4; equine rhinopneumonitis) and EHV1 (equine abortion virus) thereby identifying horses that have been infected with either or both of these antigenically related viruses. The antigens used are parts of the EHV4 and EHV1 glycoprotein G (gG) homologues expressed in E. coli as fusion proteins [Crabb and Studdert, 1993: J Virol 67: 6332-6338). The expressed proteins comprise corresponding regions of the gG molecules that are highly divergent and encompass strong, typespecific epitopes. Plasma samples from ...
Stammers JP, Hull D, Silver M, Fowden AL.The effects of different nutritional states on plasma lipid concentrations have been examined in pregnant mares and their fetuses. Maternal and fetal arterial catheters were inserted into 12 pony mares between 244-303 days' gestation (term 320-360 days) and observations made from 5 days following the insertion of catheters. After recovery from surgery maternal and fetal arterial samples were withdrawn from 7 mares with normal feeding patterns (Group IA), from four of these mares at the end of a 30 h fast and 3 h later following refeeding (Group IB) and six mares who failed to re-establish norm...
Ellis MJ, Livesey JH, Donald RA.Immunoreactive corticotrophin-releasing hormone (irCRH) was present in methanolic extracts of equine peripheral blood and showed no elevation in maternal peripheral serum in late gestation (0.54 +/- 0.25 pmol/l; mean +/- S.D.) compared with control horses (0.41 +/- 0.15 pmol/l). The irCRH of methanolic extracts of pituitary venous plasma had a similar elution position following reverse-phase HPLC to synthetic human CRH(1-41) and to irCRH released from horse stalk-median eminence tissue incubated in vitro. Gel chromatographic studies showed no evidence for a plasma CRH-binding protein (CRHBP) a...
The Journal of nutritionDecember 1, 1994
Volume 124, Issue 12 Suppl 2723S-2729S doi: 10.1093/jn/124.suppl_12.2723S
Hintz HF.Some aspects of energy, protein and vitamin E nutrition of the performance horse are discussed. The amount, dietary source and time of ingestion of energy before exercise can influence performance. In 1989 the National Research Council (NRC) increased their estimates of energy required by racehorses. Recent studies indicate that the increase was reasonable. Many factors, however, can influence energy requirements. Therefore, the best measure would be body weight and composition of the horse. A proper balance of soluble carbohydrate, fiber, fat and protein is essential. Some guidelines are pres...
van Duijkeren E, Vulto AG, Sloet van Oldruitenborghoosterbaan MM, Mevius DJ, Kessels BG, Breukink HJ, van Miert AS.The biopharmaceutical properties of four fixed trimethoprim/sulfonamide combinations were investigated in the horse. Eight fasted horses were dosed at 1 week intervals in a sequentially designed study with one intravenous (i.v.) and three oral trimethoprim/sulfadiazine (TMP/SDZ) formulations (1, 2 and 3) administered at a dose of 5 mg/kg trimethoprim (TMP) and 25 mg/kg sulfadiazine (SDZ). Plasma concentrations of each compound were monitored for 48 h. Pharmacokinetic parameters (volume of distribution, bioavailability and total body clearance) for TMP and SDZ were calculated and compared. Afte...
Toutain PL, Autefage A, Legrand C, Alvinerie M.The purpose of the present study was to establish in the horse the relationship between plasma concentration profiles of phenylbutazone (PBZ) and flunixin meglumine (FM) and their pharmacological effects in order to build a predictive pharmacokinetic/pharmacodynamic (PK/PD) model. In five horses, an experimental arthritis was induced by injecting Freund's adjuvant into a carpal joint. PBZ (4 mg/kg) and FM (1 mg/kg) were injected by the intravenous route as a single intravenous dose in two different trials. Five pharmacodynamic end-points were regularly measured after test article injection usi...
Art T, Franchimont P, Lekeux P.Ten horses underwent a standardised strenuous treadmill exercise test, before, during and after which measurements were made of plasma beta-endorphin and cortisol concentrations, blood lactate, glucose, haemoglobin and pH, the activities of creatine kinase, lactate dehydrogenase and aspartate amino-transferase, and heart rate, oxygen uptake and expired minute volume. The correlations between the exercise-induced response of beta-endorphin and the changes observed in the other physiological measurements were examined. There was a large variation in the beta-endorphin response of the horses to e...
van der Kolk JH.A 2-year-old Friesian mare was examined because she had been sluggish for a few weeks. Blood biochemistry showed that concentrations of creatinine (136 mumol.L-1) and urea nitrogen (6.1 mmol.L-1) in plasma were within their normal limits. Severe metabolic acidosis was apparent; the venous pH was 7.154 and the bicarbonate concentration was 13 mmol.L-1. The base excess amounted to -15.3 mmol.L-1 and the venous pCO2 measured 5.1 kPa. Plasma sodium was normal (135 mmol.L-1) and plasma chloride (113 mmol.L-1) was slightly elevated, but there was a hypokalaemia (2.9 mmol.L-1). The urine had a specif...
Thompson DL, DePew CL, Ortiz A, Sticker LS, Rahmanian MS.Three experiments were conducted to determine 1) the relationship between prolactin and growth hormone (GH) secretion in mares and the response to GH-releasing hormone (GHRH), 2) whether plasma GH and prolactin concentrations differed among mares, stallions, and geldings, and 3) whether sexual differences existed after administration of GHRH and acute exercise. In Exp. 1, 10-min blood samples were collected from 12 mares for 8 h, and GHRH (0, 45, 90, or 180 micrograms) was administered at 6 h. In Exp. 2, 15-min blood samples were collected for 4 h from 10 mares, stallions, and geldings. In Exp...
Castejón F, Rubio D, Tovar P, Vinuesa M, Riber C.Aerobic capacity and fitness was studied in three different horse breeds (Andalusian, Arabian and Anglo-Arabian) using a four-level exercise test of gradually increasing intensity (15, 20, 25 and 30 km/h). The lactate concentration at the first three exercise levels was significantly lower for Arabian and Anglo-Arabian horses relative to Andalusian horses, but similar for the three breeds at the last level. Arabian and Anglo-Arabian horses reached a higher rate than Andalusian horses at plasma lactate concentration of 2 mmol/l (VLA2) and 4 mmol/l (VLA4). Andalusian horses exhibited a significa...
Kamerling SG, Owens JG.The actions of most drugs are dependent upon achieving adequate plasma concentrations. Plasma concentrations are influenced by the degree to which a drug is absorbed, distributed, metabolized and excreted. Pharmacokinetic assessment reflects changes in these variables as a function of time. Pharmacodynamics refers to specific drug effects or mechanisms of drug action. Individual drug pharmacokinetics provides information on which to base a therapeutic dose, route of administration and dosing interval. However, not all drug actions temporally correlate with plasma kinetics. To resolve this disc...
Ferrante PL, Kronfeld DS.Collection of a satisfactory blood sample requires special procedures to prevent changes in glucose and lactate content after the sample has been obtained. Changes in measured plasma glucose and blood lactate concentrations attributable to anticoagulants and storage procedures, respectively, were examined in blood samples obtained from horses at rest and after exercise. To evaluate the effect of anticoagulants on measured plasma glucose concentration, blood was preserved with either sodium fluoride/potassium oxalate or lithium heparin. Measured plasma glucose concentration in blood obtained at...
Delbeke FT, Landuyt J, Debackere M.Concentrations of the non-steroidal anti-inflammatory drug (NSAID) alclofenac were determined by a sensitive high performance liquid chromatographic procedure in plasma and urine of horses following oral administration of a dose of 3 g. In plasma, alclofenac was present in detectable concentrations for 72 h. The plasma disposition in individual horses was best described by a bi-compartmental model with two successive rate constants ka1 = 0.05 +/- 0.06 h-1 and ka2 = 0.06 +/- 0.01 h-1. Alclofenac half-lives t1/2 alpha and t1/2 beta were 1.0 +/- 0.8 h and 6.9 +/- 1.5 h, respectively. Maximal conc...
Abass BT, Weaver BM, Staddon GE, Waterman AW.The pharmacokinetics of thiopentone sodium administered intravenously as a single dose (11 mg/kg) were studied in acepromazine pre-medicated horses and ponies in which anaesthesia was maintained with either halothane (Group 1) or isoflurane (Group 2). The results showed that the disposition kinetics of thiopentone in horses and ponies were best described by a three-compartment open model. In plasma, a very short initial distribution phase in both horses and ponies, half-life 1.4 +/- 1.2 min (mean +/- SD) and 1.3 +/- 0.7 min, respectively, was obtained, which was followed by a second comparativ...
Marroum PJ, Webb AI, Aeschbacher G, Curry SH.A specific, sensitive, reverse-phase high-performance liquid chromatographic assay for acepromazine, with analytic sensitivity as low as 5 ng/ml of plasma, and electrochemical detection with an oxidation potential of 0.7 V, was used to study the pharmacokinetics of acepromazine given at a dosage of 0.15 mg/kg of body weight in horses. The relation between effect and pharmacokinetics of the drug was examined. The effects studied included those on blood pressure, pulse, PCV, measures of respiration function, and sedation. Intravenously administered doses led to a biphasic concentration decay pat...
Young DB, Ewing PJ, Burrows GE, Lessley BA, Clarke CR, Shawley RV.Phenylbutazone given during the perisurgical period has been reported to increase the intensity and duration of thiamylal anaesthesia in horses. A possible mechanism of competitive plasma protein binding has been suggested. The purpose of the present study was to experimentally reproduce the phenomenon of increased intensity and/or duration of thiamylal anaesthesia and to determine if there is competitive displacement of plasma protein bound thiamylal by phenylbutazone. Six ponies each received one of three treatments, 11 mg/kg intravenous (i.v.) thiamylal; 8.8 mg/kg i.v. phenylbutazone; and 1...
DePew CL, Thompson DL, Fernandez JM, Southern LL, Sticker LS, Ward TL.Concentrations of prolactin, glucose, insulin, urea N, and total amino acids in plasma of stallions after ingestion of pelleted feed were compared to those after direct gastric administration of water, NaCl, egg albumin, or corn starch (Exp. 1) or water, egg albumin, hydrolyzed casein (Amicase), or a mixture of indispensable amino acids (Exp. 2). Stallions were fed once daily (75% pellet and 25% hay) at 1500 for 30 d. On d 22, 24, 26, 28, and 30, blood samples were collected every 30 min from 1 h before through 4 h after treatment, which occurred at 1100. In Exp. 1, there was a positive secret...
Käser R, Bruckmaier RM, Thomas S, Sieme H, Wedekind C, Burger D.Oxytocin is a hormone that may not only influence reproductive mechanisms in mammals but also their social behavior, including pair bonding. We therefore tested if the concentrations of oxytocin and other hormones reveal mate preferences of 13 mares in estrus. Each mare was first exposed to two stallions (haphazardly selected out of seven) and her behavior recorded. The mare was then returned to her box (i.e., no contact to stallions during that time). Approximately 4.5 hours later, venous blood samples were collected every minute during 30 minutes preceding exposure to one of the two previo...
Strickland K, Smith F, Woods M, Mason J.Four horses were stabled and fed a diet of hay ad libitum, and 2 kg oats per animal per day, for a month. The basic diet was then supplemented with molybdenum, at a rate of 20 mg/kg dry matter for 4.5 months. For one month of this period the diet was supplemented also with sulphur at a rate of 1.2 g/kg dry matter. Analyses of jugular blood samples, obtained at intervals varying between two and 20 days, showed no evidence of a decline in total plasma copper or of an increased proportion of trichloroacetic acid (TCA) insoluble copper in plasma over this period. In separate studies, two other hor...
McKeever KH, Scali R, Geiser S, Kearns CF.The purpose of the present study was to determine whether the training-induced hypervolaemic response seen in the horse is associated with aldosterone-mediated renal mechanisms affecting sodium conservation during the first days of training. Five healthy, Standardbred mares (weight 450-500 kg, age 4-8 years) that were unfit, but accustomed to running on the treadmill, were used to test the hypothesis that repeated submaximal exercise would alter plasma aldosterone (ALDO) concentration and renal excretion of electrolytes in horses within the first 3 days of training. The experiment consisted of...
Watts AE, Fubini SL, Todhunter RJ, Brooks MB.To identify hemostatic imbalances indicative of an increased risk of intra-abdominal adhesion formation in foals versus adult horses. Methods: Horses with colic undergoing exploratory laparotomy or abdominocentesis as part of a clinical examination (n = 16 foals ≤ 6 months of age and 19 adults ≥ 5 years of age) and horses without colic undergoing herniorrhaphy (15 foals) or euthanasia for noninflammatory and nongastrointestinal disease (10 foals and 20 adults). Methods: Paired abdominal fluid and blood samples were collected from each horse into buffered sodium citrate and centrifuged imme...
De Mello Costa MF, Anderson GA, Davies HM, Slocombe RF.Angiotensin I-converting enzyme (ACE) level measurement in blood samples is an important tool in human medicine for the detection, treatment and control of diseases such as sarcoidosis and hypertension. Recently ACE has been advocated as being correlated to athletic aptitude in human athletes and a genetic polymorphism has been shown to be responsible for the enzymatic levels in the circulation. The objective of this research was to evaluate the effects of acute exercise in horses in order to increase the understanding of a possible correlation between ACE levels in plasma and performance in e...
Rathi R, Nielen M, Cheng FP, van Buiten A, Colenbrander B.Subfertility in stallions is attributed to the inability of spermatozoa to undergo the acrosome reaction in response to progesterone. In the present study, it was assessed whether there is a correlation between stallion fertility, defined on the basis of first cycle foaling rate and first cycle 'non-return rate', and the proportion of spermatozoa with exposed progesterone receptors on their plasma membranes. Semen from Dutch Warmblood (n=10) and Friesian (n=4) stallions was analysed. Progesterone 3-(o-carboxymethyl) oxime-BSA coupled with fluorescein isothiocyanate was used as a progesterone r...
Kyvsgaard NC, Høier R, Brück I, Nansen P.Ionizing irradiation and binary ethylenimine treatment have previously been shown to be effective for in-vitro inactivation of virus in biological material. In the present study the 2 methods were tested for possible effects on measurable concentrations of reproductive hormones in equine plasma (luteinizing hormone (LH), folliclestimulating hormone (FSH), progesterone (P4), and oestradiol-17 beta (E2)). The inactivation methods were electron beam irradiation with a dose from 11 to 44 kGy or treatment with binary ethylenimine (BEI) in concentrations of 1 and 5 mmol/L. Generally, there was a clo...
Bailey MT, Christman SA, Wheaton JE, Troedsson MH, O'Brien TD, Ababneh MM, Santschi E.The aim of this study was to examine inhibin production in granulosa-theca cell tumours (GTCT). The experimental aims were: (i) to determine GTCT cell types that produce inhibin alpha- and betaA-subunits; (ii) to determine whether alpha- and betaA-subunit forms differ in GTCT fluid and normal equine follicular fluid (eFF); and (iii) to determine whether dimeric inhibin (alpha betaA) is present in GTCT plasma and tumour fluid. Plasma, tumour fluid and tumour tissue were collected from mares (n=6) with GTCT. Plasma and eFF were collected during the follicular phase from mares (n=4) undergoing no...
Kahn SK, Cywes-Bentley C, Blodgett GP, Canaday NM, Turner-Garcia CE, Vinacur M, Cortez-Ramirez SC, Sutter PJ, Meyer SC, Bordin AI, Vlock DR, Pier GB....The efficacy of transfusion with hyperimmune plasma (HIP) for preventing pneumonia caused by Rhodococcus equi remains ill-defined. Quarter Horse foals at 2 large breeding farms were randomly assigned to be transfused with 2 L of HIP from adult donors hyperimmunized either with R. equi (RE HIP) or a conjugate vaccine eliciting antibody to the surface polysaccharide β-1→6-poly-N-acetyl glucosamine (PNAG HIP) within 24 hours of birth. Antibody activities against PNAG and the rhodococcal virulence-associated protein A (VapA), and to deposition of complement component 1q (C՛1q) onto PNAG were d...
Stanley SM, Wee WK, Lim BH, Foo HC.Direct-injection LC-LC hybrid tandem MS methods have been developed for undertaking broad-based screening for acidic drugs in protein-precipitated plasma and neutral doping agents in equine urine. In both analyses, analytes present in the matrix were trapped using a HLB extraction column before being refocused and separated on a Chromolith RP-18e monolithic analytical column using a controlled differential gradient generated by proportional dilution of the first column's eluent with water. Each method has been optimised by the adoption of a mobile phase and gradient that was tailored to enhanc...
Honstein RN, Monty DE.Field investigations were conducted under natural environmental conditions to determine the physiologic responses of rested, hydrated horses (Equus caballus) to the very hot, dry weather characteristic of the summer season in southern Arizona. The emphasis of the investigation was placed on those thermoregulatory mechanisms which are involved in the maintenance of homoiothermy. Rectal temperature of the horses studied remained relatively stable throughout the day, during both cool and hot weather seasons. However, when horses were exposed to hot summer temperatures, rectal temperature (heat st...
Roska S, Morello S, Rajamanickam V, Smith LJ.Effects of lactated Ringer's solution (LRS) and hetastarch 130/0.4 (HES) on colloid osmotic pressure (COP), plasma osmolality (OSM) and total protein (TP) were investigated in 18 inhalational-anaesthetised healthy horses. Horses received 4-6 ml/kg LRS (LRS; n=9) or HES (HES; n=9) from anaesthesia induction through 60 min, after which all were administered LRS. COP, TP and OSM were measured before premedication (baseline), postinduction and 30 (n=18), 60 (n=18), 90 (n=18) and 120 (n=12) minutes. Baseline COP, OSM and TP were not different between groups. TP decreased in both groups at all t...
Novello G, Segabinazzi LGTM, Lisboa FP, Canuto LE, Freitas-Dell'Aqua CP, Dell'Aqua JA, Canisso IF.This study compared the postthaw semen parameters of stallions with high and low body condition score (BCS) and evaluated associations between body morphometric parameters and postthaw semen parameters. Twenty stallions were split into Low BCS (BCS<7, n = 11) and High BCS (BCS ≥7, n = 9) groups, and underwent a complete morphometric analysis (e.g., neck scores and circumference, crest neck height, body weight, and height), and subcutaneous body fat thickness (SFT) at the tail head, withers, shoulders, and retroperitoneal space. A fasted oral sugar test (OST) was conducted on all stallio...
Liu Y, Uboh CE, Soma LR, Li X, Guan F, You Y, Rudy JA, Chen JW.In 2008, Pennsylvania (PA) became the first State in the USA to ban and enforce the ban on the use of anabolic and androgenic steroids (AAS) in equine athletes by using plasma for analysis. To enforce the ban, a rapid and high-throughput method for analysis of 60 AAS in equine plasma was developed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Analytes were recovered from plasma by liquid-liquid extraction (LLE) using methyl tert-butyl ether, separated on a reversed-phase C₁₈ column and analyzed by electrospray ionization mass spectrometry. Multiple-reaction monitoring (MRM)...
Igwe OJ, Blake JW.The disposition kinetics of pemoline after iv and oral administration of 2.4 mg/kg of the drug were studied. The elimination half-life was 39.4 hr. The mean volume of distribution was 1.5 liters/kg indicating extensive tissue distribution and sequestration for an amphoteric drug. Plasma protein binding determined by in vitro equilibrium dialysis was concentration dependent. The mean binding capacity was found to be 0.80 mu-mol/g, an apparent dissociation constant of 3.73 X 10(-5) molar, and a total plasma protein concentration of 64.7 g/liter. The mean systemic availability by oral administrat...
Hallebeek JM, Beynen AC.In a cross-over study with six adult horses, the effect of isoenergetic replacement of dietary glucose by beetpulp on the concentration of plasma triacylglycerols was studied. The test ration contained 25% beetpulp in the dietary dry matter. The feeding of beet pulp lowered plasma triacylglycerol concentrations (p = 0.058) in the fasting state and raised the activity of heparin-released lipoprotein lipase (LPL) (p = 0.059) and the concentration of HDL2 cholesterol (p = 0.058). In the fasting state, the plasma concentrations of free fatty acids (p = 0.073) and those of beta-hydroxybutyrate (p =...
Nóbrega Neto PI, Luna SP, Queiroz-Williams P, Mama KR, Steffey EP, Carregaro AB.This study investigated the antinociceptive effects of a constant rate infusion (CRI) of lidocaine during xylazine and ketamine anesthesia in horses and aimed to correlate these effects with cardiorespiratory variables, bispectral index (BIS) and plasma lidocaine concentrations. Six adult crossbred mares weighing 320-400 kg were anesthetized on three different occasions. Sedation was performed with xylazine (0.75 mg/kg IV) and anesthetic induction with guaifenesin (75 mg/kg IV) and ketamine (2 mg/kg IV). Anesthesia was maintained with 37.5 μg/kg/min of xylazine and 87.5 μg/kg/min of ketamine...
Ohmura H, Hiraga A, Aida H, Takahashi T, Nukada T.To determine oral dosage and to evaluate the pharmacokinetics in horses of orally administered flecainide, an antiarrhythmic drug, the correlations between its plasma concentration and PR, QRS and QT intervals in equine electrocardiograms (ECG) were investigated. Six healthy horses were administered a randomly ordered dose of 4 or 6 mg/kg of flecainide acetate. The ECG was monitored (heart rate (HR), PR, QRS, and QT intervals) and blood was taken at timed intervals to measure the plasma flecainide concentrations pre- and post-administration. The maximum plasma concentration reached 1014+/-285 ...
Delbeke FT, Debackere M.The prototype of a commercial ELISA test kit designed for fentanyl determination in human urine has been evaluated for screening fentanyl in horse urine and plasma. The measurement of fentanyl after intravenous (2 mg) and intramuscular (0.25 mg) administration in undiluted plasma was not reproducible while accurate quantification of fentanyl in urine greatly depends on the composition of the horse urine. The ELISA assay, however, is simple and could be successfully used for quantitative measurements in diluted urine and for rapid qualitative screening for fentanyl in large numbers of urine sam...
Cochran RA, Leonardi-Cattolica AA, Sullivan MR, Kincaid LA, Leise BS, Thompson DL, Godke RA.The effects of exogenous equine somatotropin (eST) administration on ovarian activity and plasma hormone levels were evaluated on horse and pony mares. The objectives of this study were to determine the effects of eST on follicular development and circulating concentrations of leutinizing hormone (LH), estradiol, progesterone, and insulin-like growth factor I (IGF-I) in cyclic horse and pony mares. Sixteen mares received daily injections (i.m.) of eST at a concentration of 25 micrograms/kg body weight on either Days 6 through 12 (Treatment A) or 13 through 19 (Treatment B) postovulation. In ad...
Brennan KM, Graugnard DE, Spry ML, Brewster-Barnes T, Smith AC, Schaeffer RE, Urschel KL.To determine effects of a microalgae nutritional product on insulin sensitivity in horses. Methods: 8 healthy mature horses. PROCEDURES :Horses (n = 4/group) received a basal diet without (control diet) or with docosahexaenoic acid-rich microalgae meal (150 g/d) for 49 days (day 0 = first day of diet). On day 28, an isoglycemic hyperinsulinemic clamp procedure was performed. Horses then received dexamethasone (0.04 mg/kg/d) for 21 days. On day 49, the clamp procedure was repeated. After a 60-day washout, horses received the alternate diet, and procedures were repeated. Plasma fatty acid, gluco...
Zicker SC, Rogers QR.Concentrations of amino acids in plasma and whole blood in response to 10 hours of food deprivation were determined in healthy 2-day-old foals (n = 8) and were compared with control values in foals of the same age (n = 8) allowed free access to suckle. In addition, response of concentrations of amino acids in plasma to 15 minutes of free-access suckling was determined at the end of the 10-hour period in both groups. Response of 13 amino acids in plasma of food-deprived foals was significantly (P < 0.05) different, compared with that in control foals. Concentrations of 3 amino acids (alanine...
Keen B, Cawley A, Reedy B, Noble G, Loy J, Fu S.The use of catechol-O-methyltransferase inhibitors may mask doping agents, primarily levodopa, administered to racehorses and prolong the stimulating effects of dopaminergic compounds such as dopamine. It is known that 3-methoxytyramine is a metabolite of dopamine and 3-methoxytyrosine is a metabolite of levodopa thus these compounds are proposed to be potential biomarkers of interest. Previous research established a urinary threshold of 4,000 ng/mL for 3-methoxytyramine to monitor misuse of dopaminergic agents. However, there is no equivalent biomarker in plasma. To address this deficiency a...
Enbergs H, Karp HP, Schönherr U.The present study was aimed to determine the contents of calcium, inorganic phosphate, parathormon, 25-OH-D3 and the activity of alkaline phosphatase in the plasma of one- and two-years-old thoroughbred horses. Data were obtained monthly from 44 one-year-old thoroughbred of 4 different studs from May during grazing-season and from October during stable-, resp. training-season up to april of the following year. Calcium, inorganic phosphate and the activity of alkaline phosphatase were measured with a photometric method and the concentration of PTH and 25-OH-D3 were determined with a radioimmuno...
Stoneham SJ, Digby NJ, Ricketts SW.The importance of colostrum for the passive transfer of maternal immunity to foals is well recognised. This survey reports the incidence of the failure of passive transfer of colostral immunity in thoroughbred foals in the United Kingdom during 1988 to 1990, and the effect of plasma transfusions on IgG levels in a group of them. The incidence of disease in these foals first month of life is also recorded.
Waterman AE, Amin A.The plasma concentration of pethidine was measured in 16 horses, after its administration intravenously (i.v.) at a dose rate of 1 mg/kg bodyweight (bwt). In eight animals studied before surgery, the plasma levels of the drug decreased in a bi-exponential manner with a distributive half life of 3 mins and an elimination half life of 57.7 mins. Total body clearance was 17.7 ml/kg bwt/min. The remaining horses were investigated immediately after a period of anaesthesia and surgery and in these animals the drug exhibited smaller volumes of distribution (V1 cand Vdarea) and a significantly lower c...
Lees P, Higgins AJ, Mawhinney IC, Reid DS.The absorption pattern of phenylbutazone was studied in five horses during administration of the drug in a paste formulation on days 1, 5, 8 and 12 of a 12-day dosing schedule. Since two or more plasma concentration peaks were usually obtained following each oral dose, it was concluded that phasic absorption was a particular feature of the oil:water formulation of the product. Possible causes of this unusual absorption pattern are discussed and the therapeutic implications of both phasic absorption and the recorded values of Cmax, tmax and AUC024 for phenylbutazone and its active metabolite ox...
Pearce SG, Grace ND, Firth EC, Wichtel JJ, Holle SA, Fennessy PF.The effect of copper supplementation of pasture fed mares and foals on the copper status of the foals, in terms of plasma, soft tissue and bone copper concentrations and caeruloplasmin activity, was investigated. Twenty-one Thoroughbred foals from either control mares (n = 9), or copper-supplemented mares (n = 12) were divided randomly into control (pasture only, n = 10) or supplemented (pasture and oral copper sulphate, n = 11) groups. The pasture diet was grazed by all animals, and contained 4.4-8.6 mg Cu/kg dry matter (DM). The copper supplement for the mares contained copper sulphate equiv...
Knych HK, Kanarr K, Fang Y, McKemie DS, Kass PH.To describe the pharmacokinetics, behavioral and physiologic effects and effects on thermal thresholds of morphine, morphine 6-glucuronide (M6G) and morphine 3-glucuronide (M3G) following administration to horses. Methods: Randomized balanced crossover study. Methods: A total of seven University-owned horses, five mares and two geldings, aged 3-6 years. Methods: Horses were treated with a single intravenous dosage of saline, morphine (0.2 mg kg), M6G (0.01 mg kg) and M3G (0.03 mg kg). Blood was collected prior to (baseline) and at several times post administration. Drug and metabolite concentr...
Higgins AJ, Lees P, Sharma SC, Taylor JB.An accurate and reliable method for the separation of flunixin from, and measurement in, equine inflammatory exudate and plasma by high performance liquid chromatography has been developed. Flunixin can be detected in concentrations as low as 0.05 micrograms/ml using an ultraviolet spectrophotometric detector at 285 nm. Samples were acidified with 2M hydrochloric acid and extracted with dichloromethane. The extract was evaporated and reconstituted in acetonitrile. Iminodibenzyl was used as internal standard. The mean recovery of flunixin from plasma was 97.6 +/- 3.9 per cent. Particular advant...
