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.
Stoltz MA, van der Merwe CF, Coetzee J, Huismans H.The subcellular localization of the minor nonstructural protein NS3 of African horsesickness virus (AHSV) has been investigated by means of immunogold electron-microscopical analysis. NS3 was observed in perturbed regions of the plasma membrane of AHSV-infected VERO cells, and its presence appears to be associated with events of viral release. These events are budding, whereby released viruses acquire fragments from the host-cell membrane, as well as by the extrusion of nonenveloped particles through the cell membrane. The membrane association of NS3 was confirmed by its detection in the disru...
Orsini JA, Park MI, Spencer PA.Concentrations of amikacin in endometrial tissue and plasma were studied in mares in estrus after intrauterine infusion of 1.0 or 2.0 g once a day for 3 consecutive d, and after 9.7 or 14.5 mg/kg body weight (BW) had been injected intramuscularly once a day for 3 consecutive d to determine concentrations of amikacin sulfate in plasma and endometrial tissues, and whether parenteral administration provides any advantages over intramuscular infusion. No amikacin was detected in serum at the 1.0 g dose. At the infusion dose of 2.0 g once a day, very low levels of serum amikacin were detected at 1 ...
Kristinsson J, Thordarson TH, Johannesson T.The pharmacokinetics of lignocaine was studied in four Icelandic horses after infiltration anaesthesia. A total of 240 mg of the drug was injected on either side of the left foreleg, over the medial and lateral branches of the palmar nerve. Blood samples were collected up to seven hours after injection and the concentrations of the drug in plasma were determined by gas chromatography/mass spectrometry. The results showed that lignocaine was rapidly absorbed. A mean maximum concentration of 232 ng/ml was observed after 20 minutes. In three of the horses the decline in the plasma concentration o...
Lillich JD, Bertone AL, Schmall LM, Ruggles AJ, Sams RA.OBJECTIVE--To document plasma, urine, and synovial fluid disposition of 2 common intra-articularly administered steroid preparations, methylprednisolone acetate (MPA) and isoflupredone acetate (IPA). DESIGN--Descriptive investigation. SAMPLE POPULATION--100 mg of MPA or 4 mg of IPA was administered to 2 groups of 4 healthy sound radiographically normal female horses. PROCEDURE--Blood samples were collected at time 0 (before) and 2, 4, 6, 8, 10, 12, 24, 36, 48, 72, and 96 hours after administration of the designated steroid. Complete urine collection for measurement of designated steroid was ac...
Nouri-Sorkhabi MH, Agar NS, Sullivan DR, Gallagher C, Kuchel PW.The phospholipid classes of erythrocyte membranes and plasma from several domestic animals and marsupials were quantified by 31P NMR using detergents. Washed erythrocyte samples were thoroughly haemolysed by tip-sonication and dissolved in sodium cholate; plasma samples were dissolved in Triton X-100. The species studied were: common wombat (Vombatus ursinus), black-striped wallaby (Macropus dorsalis), bandicoot (Isoodon macrocarpus), Eastern grey kangaroo (Macropus giganteus), Tammar wallaby (Macropus eugenii), sheep (Ovis aries), goat (Capra hircus), cattle (Bos taurus), horse (Equus caballu...
González G, Ventura R, Smith AK, de la Torre R, Segura J.A gas chromatographic-mass spectrometric (GC-MS) procedure for the detection of seventeen non-steroidal anti-inflammatory drugs (NSAIDs) in equine plasma and urine samples is described. The extraction of the compounds from the biological matrix was performed at acidic pH (2-3) with diethyl ether. Ethereal extracts were washed with a saturated solution of sodium hydrogencarbonate (urine) or treated with a solid mixture of sodium carbonate and sodium hydrogencarbonate (plasma). The ethereal extracts were dried and derivatized by incubation at 60 degrees C with methyl iodide in acetone in the pre...
Mills PC, Smith NC, Casas I, Harris P, Harris RC, Marlin DJ.The effects of prolonged variable-intensity and short-term high-intensity exercise on indices of oxidative stress and iron homeostasis were compared in six fit horses under cool [20 degrees C, 40% relative humidity (RH)] or hot/humid (30 degrees C, 80% RH) environmental conditions. The exercise protocols were designed to simulate equine competition, including racing (intense exercise) or the speed and endurance phase of a 3-day event (prolonged exercise). Increased plasma concentrations of lipid hydroperoxides and haemolysate concentrations of oxidised glutathione (GSSG) were measured within 3...
Cárdenas S, Gallego M, Valcárcel M, Ventura R, Segura J.A partially automated module for the routine determination of illicit non-steroid antiinflammatory drugs (NSAIDs) in biological fluids from race horses was built, tested, refined, and shown to work. This pretreatment module retains 17 NSAIDs on an Amberlite XAD-2 column before back-elution derivatization with methyl iodide in acetonitrile. Methylated derivatives are manually injected into a gas chromatograph connected to a mass spectrometer. The quantification limits thus achieved are 50-100 ng/mL in 1 mL of urine or plasma. The proposed method is more expeditious than its manual liquid-liquid...
Desmecht D, Linden A, Amory H, Art T, Lekeux P.Fifty-eight healthy horses were studied during five sporting events of various intensities and durations, namely show-jumping (n = 6), cross-country in a three-day event (n = 30), trotting races (n = 7), galloping races (n = 7) and endurance rides (n = 8). Venous blood samples were collected at rest and immediately after exercise and analysed for plasma cortisol (CORT) and lactate (LA) levels. The experimental procedure was the same throughout the investigation so as to permit a reliable comparison between the five types of exercise. The type of event significantly affected both the resting (p...
Ensink JM, Moi A, Vulto AG, Tukker JJ.Pivampicillin was administered as an oral paste to five healthy adult horses, and an oral paste with ampicillin trihydrate was administered to three horses. Pivampicillin was administered to both starved and fed horses, ampicillin trihydrate was administered to fed horses only. The dose of pivampicillin was 19.9 mg/kg, and the dose of ampicillin trihydrate was 17 mg/kg. Both doses are equivalent on a molecular basis to 15 mg/kg ampicillin. Ampicillin concentrations in plasma were determined up to 24 hours after administration. After administration of pivampicillin to starved and fed horses the...
Couëtil L, Paradis MR, Knoll J.Pituitary adenomas are commonly reported in older horses. The typical clinical signs associated with this condition, also known as equine Cushing's disease (ECD), are related to increased adrenocorticotropin (ACTH) production resulting in hyperadrenocorticism. The primary purpose of this study was to determine whether plasma ACTH concentrations differed between cushingoid and healthy horses. The second objective was to determine the effects of blood sample handling techniques on ACTH concentrations. A commercial human ACTH radioimmunoassay (RIA) was used to quantify equine plasma ACTH. Intra-a...
Weidmeyer CE, Solter PF.The Incstar(R) SPQ II human haptoglobin (Hpt) (Incstar Corporation, Stillwater, MN) immunoturbidimetric assay was validated for the determination of serum and plasma Hpt concentrations in dogs and horses. The anti-human Hpt antiserum supplied with the assay, displayed monospecificity to both dog and horse serum Hpt by immunoelectrophoresis and Western blotting techniques. The automated immunoturbidimetric assay results correlated well with the cyanmethemoglobin binding assay (r=0.953 for canine serum and r=0.941 for equine serum), and had excellent precision at both high and low serum Hpt conc...
Fujii T, Yamada S, Yamaguchi N, Fujimoto K, Suzuki T, Kawashima K.Various concentrations of acetylcholine (ACh) were detected in samples of bovine, goat, horse, porcine, rat and sheep blood and plasma using a specific, sensitive radioimmunoassay. The ACh levels in whole blood in bovine and horse samples were about 40- and ten-fold higher, respectively, than in humans, but levels comparable to those in humans were measured in porcine samples. Goat, rat and sheep samples had lower whole blood ACh concentrations than those of humans. When plasma samples were assayed, the ACh contents of bovine and porcine plasma were found to be about two- to five-fold those of...
Ozawa A, Inokuma H, Johke T.The relationship between plasma insulin-like growth factor-I (IGF-I) level and body weight was studied in six breeds of horse. The correlation coefficients between plasma IGF-I and body weight in males and females of 1 year old heavy horses (Percheron and Breton breeds) were 0.62 and 0.12 respectively. The mean plasma IGF-I of males was higher than that of females (p < 0.01). However, the plasma IGF-I levels of heavy horses did not exceed those of light horses (Thoroughbred) or ponies (Shetland and Falabella). These data suggest that IGF-I is at least related to the difference of body weights ...
Mills PC, Dunnett M, Smith NC.The pharmacokinetics of oral and intravenous allopurinol was studied in five horses and compared with intravenous oxypurinol. The plasma concentration vs. time curves, following intravenous administration of 5 mg/kg, were best described by the biexponential equations Cp = 106.58e(-25.14t) + 159.93e(-10.96t) for allopurinol and Cp = 321.09e(-9.72t) + 82.39e(-0.44t) for oxypurinol, with an elimination half-life (t1/2 beta) of 0.09 h and an area under the curve (AUC) of 19.8 mumol.h/L after intravenous administration, while the t1/2 beta and AUC of oxypurinol were 1.09 h and 231 mumol.h/L, respec...
Escribano BM, Castejon FM, Santisteban R, Aguera EI, Rubio MD.A study has been made of the variations experienced by the hemogram and blood volume indices in 16 Andalusian horses after carrying out an exercise test of increasing intensity consisting of 3 sequences of 1000 m each, before and after being subjected to a daily exercise programme for two months. Samples were taken by external jugular vein puncture: while at rest, within the first minute of finalizing each exercise stage and at 10 and 15 minutes of recovery. Both the red blood cells and the hematocrit value showed a significant decrease in their mean values after two months training; conversel...
Sticker LS, Thompson DL, Bunting LD, Fernandez JM, DePew CL, Nadal MR.Twelve light horse mares were fed a control diet that provided 100% of their maintenance protein and energy requirements for 7 d and were then either continued on the control diet or totally deprived of feed (with access to water) for 3 d . Plasma samples were drawn twice daily throughout the experiment, at 15-min intervals for 9 h beginning 45 h after feed removal, and at 10-min intervals around an exercise bout beginning 73 h after feed removal. Feed deprivation increased (P < or = .06) whole blood beta-hydroxybutyrate and plasma NEFA, urea N, L-lactate, and glucagon concentrations, decrease...
Bell K, Arthur H, Breen M.Eleven apparent mutations of the equine plasma transferrin and esterase gene (10 in TF and one in ES) were found in an analysis of approximately 240,000 thoroughbred horses. Eight of the transferrin mutations produced variants not previously recognized in horses. In the two remaining transferrin mutations and the esterase mutation, reduced plasma concentrations of the proteins were demonstrated by immunological techniques and together with the family data indicated the existence of 'null' alleles.
van der Kolk JH, Wisse H, van Dijk S.A 20-year-old Arab crossbred gelding was examined because it had apparently suffered an overstimulation of the parasympathetic nervous system for three hours. The clinical signs consisted of hypersalivation, profuse sweating, maximal miosis, fasciculation of the muscles and lateral recumbency in combination with continuous convulsions without diarrhoea. The horse's plasma pseudocholinesterase activity was approximately 10 per cent of normal. It responded well to 10 mg atropine and 50 mg diazepam administered intravenously.
Hurley JR, Begg AP.A trial was conducted on a Thoroughbred stud to determine whether or not the administration of anti-Rhodococcus equi hyperimmune plasma would reduce the prevalence of R equi pneumonia (rattles) in foals born in the 1992 horse breeding season. Hyperimmune plasma was administered to 34 foals; another 57 foals were untreated. There was no significant difference in the number of transfused foals developing R equi pneumonia compared with the untreated foals. The time required for recovery from pneumonia between the 2 groups was not significantly different.
Harris PA, Marlin DJ, Scott CM, Harris RC, Mills PC, Michell AR, Orme CE, Roberts CA, Schroter RC, Marr CM.Four horses (H, J, N and M) undertook a simulated competition exercise test (CET), designed to simulate physiological and metabolic stresses of the Speed and Endurance (S & E) test of a 3-day-event, under 3 different environmental conditions: 20 degrees C/40% relative humidity (RH) (cool, dry [CD] 2 sessions); 30 degrees C/40% RH (hot, dry [HD]) and 30 degrees C/80% RH (hot, humid [HH]) (Marlin et al. 1995a). Venous blood samples for electrolyte and total protein (TP) determinations were collected from indwelling catheters at predetermined time points throughout each CET and initial 30 min...
White SL, Williamson LH, Maykuth PL, Cole SP, Andrews FM.The exercise intensity of horses competing in 3-day combined training events at 3 different levels of competition (CCI, n = 7; CCI, n = 11; CCI, n = 23) was investigated. Environmental conditions during all events were cool with 100% cloud cover. Heart rates were continuously recorded at 5 s intervals by a heart rate monitor. Mean +/- s.d. heart rate for all horses during each phase were: Phase A = 118 +/- 11 beats/min, Phase B = 179 +/- 22.7 beats/min, Phase C = 129 +/- 13.9 beats/min and Phase D = 174 +/- 19.6 beats/min. Mean +/- s.d. heart rates on Phase A and C were significantly different...
Cargile JL, MacKay RJ, Dankert JR, Skelley L.A monoclonal antibody (MAB) against equine tumor necrosis factor-alpha (Eq TNF) was used to investigate the role of TNF in cytokine, eicosanoid, and metabolic responses of Miniature Horses given endotoxin. Plasma concentrations of interleukin 6 (IL-6), lactate, thromboxane A2 metabolite, and prostacyclin metabolite (6-keto-PGF1 alpha) were measured in 10 Miniature Horses given 0.25 microgram of lipopolysaccharide (LPS; Escherichia coli O55:B5)/kg of body weight. Five horses were given Eq TNF MAB and 5 were given isotype-matched MAB as control. All horses were given 1.86 mg of antibody/kg by IV...
Sosa León LA, Davie AJ, Hodgson DR, Rose RJ.Effects of different tonicities, glucose concentrations and temperatures of an oral rehydration solution (ORS) on its uptake and elimination in resting horses were studied. Fluid and electrolyte deficits similar to those occurring during prolonged exercise were induced by the administration of 1 mg/kg bwt of frusemide i.m., 3 h prior to the ORS. Fluid was administered via nasogastric tube at a volume equivalent to 4% bodyweight, which approximated diuretic induced losses. The uptake of fluid was evaluated by changes in haematocrit (PCV) and plasma total protein concentration (TP). Changes in e...
Marlin DJ, Harris PA, Schroter RC, Harris RC, Roberts CA, Scott CM, Orme CE, Dunnett M, Dyson SJ, Barrelet F.The present study was undertaken to investigate physiological, metabolic, haematological and biochemical changes in horses competing in the Speed and Endurance test of a Concours Complet International (CCI)*****3-day-event held under FEI rules. A total of 28 horses competing in the Burghley Horse Trials Speed and Endurance test were selected to be monitored: 11 horses in 1993 and 17 horses in 1994. Of the 28 horses selected, 17 completed the Speed and Endurance test and went on to complete the showjumping test. Mean +/- s.d. shade temperature and relative humidity, black globe temperature and ...
Jansson A, Nyman S, Morgan K, Palmgren-Karlsson C, Lindholm A, Dahlborn K.In this study 4 Standardbred geldings (age 3-8 years, weight 431-531 kg) were used. The horses were fed a hay and oat diet and the total sodium intake was about 32 mg/kg bwt (690 mmol/day). An exercise test (ET) which contained 3 phases was performed. Phase I consisted of 23.5 min of mainly submaximal exercise, Phase 2 of 2 h of box rest and Phase 3 of 26 min of exercise including an intensive trot over 2600 m at 90% of VO2max. The ET was repeated 3 times: the first at 20 degrees C (30-40% RH), the second at 35 degrees C (30-40% RH) and the third at 35 degrees C (30-40% RH) after a nasogastric...
Aramaki S, Suzuki E, Ishidaka O, Momose A.The effects of exercise on the metabolism of caffeine (CA) were studied 3h after administration of the drug to race horses which then underwent exercise sets (1000-m gallop). Analysis was made of pharmacokinetics of CA, changes in its plasma concentrations, its metabolites, i.e., theophylline (TP), theobromine (TB) and paraxanthine (PX), and the molar concentration ratios of CA to these metabolites. After exercise, AUC and t1/2 tended to decrease, and the concentration of CA decreased, while the concentrations of TP and TB significantly increased. The TP/CA ratio and TB/CA ratio significantly ...
Geiser DR, Andrews FM, Rohrbach BW, White SL, Maykuth PL, Green EM, Provenza MK.Blood ionized calcium (Ca2+) and pH; plasma lactate concentrations; and total protein, total calcium (CaT), albumin, and phosphorus concentrations in serum were determined in 40 healthy horses before (T1), at the finish line (T2), and 10 minutes after the finish (T3) of the cross-country phase of a 3-day-event competition. Mean (+/- SEM) Ca2+ concentrations decreased from 6.22 +/- 0.04 mg/dl at T1 to 5.04 +/- 0.07 mg/dl at T2 (P < or = 0.05). This decrease was accompanied by a nonsignificant increase in CaT between T1 and T2. The mean (+/- SEM) percent ionization of calcium decreased significa...
Ecker GL, Lindinger MI.Loss of total body water and ions during prolonged exercise can predispose the horse to health and performance problems. This study examined total body water (TBW) losses and extracellular (ECF) ion losses during the cross-country (XC) phase of Preliminary, Intermediate and Advanced Horse Trials and CCI level 3-day-events. Jugular venous blood samples and body mass (BM) were collected on 49 horses at rest, Pre-XC, Post-XC and following 30 min of recovery. Plasma was separated from blood cells within 10 min of collection. Plasma was analysed for [Na+], [K+], [Cl-], ionised [Ca+2], [glucose], [l...
Lindinger MI, Geor RJ, Ecker GL, McCutcheon LJ.We studied the effects of heat and relative humidity (RH) on plasma volume (PV) and ion responses to submaximal exercise and 60 min recovery in Thoroughbreds. Five horses were exercised at 50% of peak VO2 in cool, dry (CD, T = 22 degrees C, RH = 45-55%), and hot, humid (HH, T = 30-34 degrees C, RH = 80-85%) conditions until a pulmonary artery temperature of 41.5 degrees C was reached. Blood was obtained from the carotid artery. Body mass was measured at rest and after 30 min of recovery. The thermal conditions had no effect on the PV and ion responses during exercise and initial 30 min of reco...
Ho EN, Kwok WH, Lau MY, Wong AS, Lam KK, Stewart BD, Wan TS.Granulocyte colony-stimulating factor (G-CSF) is a hematopoietic growth factor regulating granulopoiesis. The recombinant human granulocyte colony-stimulating factor (rhG-CSF) is widely used for the treatment of granulopenia in humans. Filgrastim is a rhG-CSF analogue and is marketed under various brand names, including Neupogen(®) (Amgen), Imumax(®) (Abbott Laboratories), Neukine(®) (Intas Biopharmaceuticals) and others. It is banned in both human and equine sports owing to its potential for misuse. In order to control the abuse of filgrastim in equine sports, a method to identify unequivo...
Allen D, Korthuis RJ, Clark S.A pump-perfused extracorporeal digital preparation was used to evaluate blood flow, arterial pressure, venous pressure, isogravimetric capillary filtration coefficient, capillary pressure, and vascular compliance in six normal horses. From these data, pre- and postcapillary resistances and pre- and postcapillary resistance ratios were determined. Vascular and tissue oncotic pressures were estimated from plasma and lymph protein concentrations, respectively. By use of the collected and calculated data, tissue pressure in the digit was calculated using the Starling equation. In the isolated equi...
Neto LM, Andraus MH, Salvadori MC.A method is described for the qualitative and quantitative determination of phenylbutazone and oxyphenbutazone in horse urine and plasma samples viewing antidoping control. A horse was administered intravenously with 3 g of phenylbutazone. For the qualitative determination, a screening by HPLC was performed after acidic extraction of the urine samples and the confirmation process was realized by GC-MS. Using the proposed method it was possible to detect phenylbutazone and oxyphenbutazone in urine for up to 48 and 120 h, respectively. For the quantitation of these drugs the plasma was deprotein...
Thompson DL, Garza F, Mitchell PS, St George RL.Long-term ovariectomized pony mares were subjected to one of four treatments: 1) control group - no treatment, 2) stressed group - 5 min of restraint via a twitch, 3) tranquilized group - administered xylazine (1.1 mg i.v. per kg of body weight), and 4) anesthetized group - administered xylazine followed 2 min later by ketamine (2.2 mg i.v. per kg of body weight). Blood samples were taken at -40, -30, -20, -10, -0.5, 10, 20, 30, 40, 50, 60 and 90 min and at 2, 3, 4, 6, 8 and 24 h relative to onset of treatment. Stress increased (P<0.05) cortisol concentrations 20 to 50 min after treatment a...
Kolm G, Helsberg A, Gemeiner M.The effect of factors including the horses' farm environment, their sex and age and whether they suffered from summer seasonal recurrent dermatitis (sweet itch) on the concentrations of zinc in the plasma, whole blood and blood cells of 104 Icelandic horses was investigated. Its concentration in plasma varied significantly between farms (P<0.01), but its concentration in blood and blood cells was not influenced by any of the variables. The concentration of zinc in the blood cells was 10.5 times greater than in plasma, but its concentration in plasma was not correlated with its concentration in...
Alonso JM, Peccinini RG, Campos ML, Nitta TY, Akutagawa TYM, Crescencio AP, Alves ALG, Rodrigues CA, Watanabe MJ, Hussni CA.Intraperitoneal (IP) use of antimicrobial agents may lead to therapeutic effects with better clinical results than intravenous (IV) administration. The aim of this study was to compare plasma and peritoneal fluid concentrations of ceftriaxone after IP and IV administration in horses, and to evaluate possible adverse effects. One group of five horses received 25mg/kg ceftriaxone diluted in 1L saline solution by IP catheter once daily for 5 days, while a second group of five horses received 25mg/kg ceftriaxone diluted in 250mL saline solution by IV injection once daily for 5days and 1L saline so...
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...
Greene EW, Woods WE, Tobin T.Caffeine (4 mg/kg) was given by rapid IV injection to 4 horses. Plasma concentrations of the drug peaked at 10 micrograms/ml and decreased rapidly at first, and then more slowly, with an apparent beta-phase half-life of 18.2 hours. Urinary concentrations of caffeine were remarkably consistent at about 3 times plasma values of the drug. Caffeine was detectable in both plasma and urine of the horses for up to 9 days after dosing. After oral administration, caffeine was absorbed poorly with an apparent bioavailability of 39%. Although blood concentrations of caffeine peaked rapidly after oral adm...
McConkey S, López A, Pringle J.A Clydesdale mare was examined for weight loss, inappetence, ptyalism, and dysphagia. The main abnormality revealed by serum biochemistry was a marked hyperglobulinemia, and protein electrophoresis revealed a monoclonal gammopathy in the gamma region. The urine was positive for Bence Jones proteins. These findings suggested a plasma cell tumor. The neoplasm could not be located with extensive antemortem examination. At postmortem, neoplastic cells morphologically compatible with plasma cells and positive for equine IgG with imunoperoxidase staining infiltrated the pericardium, mediastinal stro...
Ferrante PL, Freeman DE, Ramberg CF, Kronfeld DS.Multicompartmental analysis was applied to study the kinetics of D-xylose distribution after its intragastric administration to healthy mares deprived of food for 12, 36, 72, and 96 hours. Disposition of D-xylose was described by a 5-compartment model. Maximal plasma D-xylose concentration was similar for 12 and 36 hours of food deprivation and was greater (P = 0.0001) than the values for 72 and 96 hours. Peak concentration of D-xylose appeared progressively later as food deprivation proceeded (P = 0.0001). Fractional rate of transfer (k1,6) was less after 96 hours of food deprivation, compare...
Veronesi MC, Faustini M, Villani M, Kindahl H, Galeati G, Battocchio M.The aim of the present study was to highlight the effect of two different techniques of one embryo crushing on some hormonal changes. Ten twinning mares were submitted to the mobile or fixed manual crushing of one blastocyst within day 19 after the last mating. Blood sample was collected from 20 min before to 90 min, 24 and 72 h after the procedure was performed to analyse 15-ketodihydro-PGF(2alpha), cortisol and progesterone plasma concentrations. Singleton pregnancy diagnosis was checked 72 h after crushing and at term of pregnancy. Because the unwanted crushing of both embryos occurred in o...
Patterson SD, Auer D, Bell K.The induction of an acute phase response in four horses by adjuvant administration was used to examine the effect on the levels of plasma proteins. Blood parameters (packed cell volume, total plasma protein, red blood cell count, haemoglobin concentration) were monitored to follow the progress of the acute phase response in parallel with the examination of plasma proteins. Plasma protein levels were determined by densitometry from the electrophoretic patterns of three different gel systems. Haptoglobin and alpha 1 B glycoprotein were shown to be positive acute phase reactants whereas albumin w...
Romagnoli U, Macchi E, Romano G, Motta M, Accornero P, Baratta M.The aim of this work is to investigate on plasma profiles of leptin and estradiol 17beta during the interpartum period and leptin concentrations in the milk and in the colostrum during the period from parturition to the successive delivery in mare. Leptin plasma concentration varied from 5.1+/-2.3 ng/ml after the first parturition (week 0) to 3.0+/-0.7 at week 21 (p<0.05), then it increased to maximal level at week 49 (6.9+/-1.0 ng/ml, p<0.05). Leptin concentration in the colostrum and in the milk has been significantly (p<0.05) higher than that in plasma samples at week 1 (milk 8.8+/...
Machin J, Duer W, Maylin G, Fenger C, Wilson D, Ivey M, Berthold B, Allison S, Tobin T.Methylprednisolone (MP) acetate is a commonly used corticosteroid for suppression of inflammation in synovial structures in horses. Its use is often regulated in equine sports by plasma MP concentrations. Objective: To describe variability in MP plasma concentrations after MP acetate injection in different synovial structures and with co-administration with hyaluronic acid (HA). Methods: Field study in actively racing horses in three disciplines (Thoroughbred, Standardbred and Quarter Horse). Methods: Seventy-six horses (15 Thoroughbreds, 20 Standardbreds and 41 Quarter Horses) were included i...
Tinkler SH, Couëtil LL, Kennedy SA, Constable PD.To determine whether plasma total CO(2) concentrations would vary with the size of the evacuated tube used to collect blood samples. Methods: Randomized crossover study. Methods: Convenience sample of 20 healthy adult horses. Methods: Jugular venous blood was collected from horses in random order into 8 types of evacuated tubes: 2-mL glass, 2- or 3-mL plastic or plastic plasma separator, 4- or 6-mL plastic, and 10-mL glass or plastic. Total CO(2) concentrations in plasma were measured with a biochemistry analyzer. Data were analyzed via repeated-measures ANOVA and multivariate regression. Resu...
DeBoer ML, Martinson KL, Kuhle KJ, Sheaffer CC, Hathaway MR.The impact of forage species on plasma amino acid (AA) concentrations of grazing horses (Equus caballus L.) is unknown. The objectives of this study were to determine the impact of different forage species on plasma AA concentrations and protein synthesis. Research was conducted in July in St. Paul, MN, USA. Alfalfa (Medicago sativa L.), mixed perennial cool-season grasses (CSGs), and teff (Eragrostis tef [Zucc.] Trotter) pastures were grazed by six horses randomly assigned to one of three forage types in a replicated Latin-square design. Horses had access to pasture each day. Jugular venous b...
Harding C, Viljanto M, Cutler C, Habershon-Butcher J, Biddle S, Scarth J.Oxandrolone is an anabolic-androgenic steroid with favourable anabolic to androgenic ratio, making it an effective anabolic agent with less androgenic side effects. Although its metabolism has been studied in humans, its phase I and II metabolism has not been previously reported in the horse. The purpose of this study was to investigate the in vitro metabolism of oxandrolone (using both equine liver microsomes and S9) and in vivo metabolism following oral administration (three daily doses of 50 mg of oxandrolone to a single Thoroughbred horse), using both gas and liquid chromatography-mass s...
Houston T, Chay S, Woods WE, Combs G, Kamerling S, Blake JW, Edmundson AG, Vessiney R, Tobin T.A survey of plasma and urinary concentrations of phenylbutazone and its metabolites in thoroughbred horses racing in Kentucky was carried out. Post-race blood samples from more than 200 horses running at Latonia Racetrack and Keeneland in the Spring of 1983 were analysed. The modal plasma concentration of phenylbutazone was between 1 and 2 micrograms/ml, the mean concentration was 3.5 micrograms/ml and the range was up to 15 micrograms/ml. Oxyphenbutazone had a modal plasma concentration between 1 and 2 micrograms/ml, a mean concentration of 2.07 micrograms/ml and a range of up to 13 microgram...
Timms M, Ganio K, Forbes G, Bailey S, Steel R.CJC-1295 is a 30 amino acid peptide-based drug that stimulates the release of growth hormone (GH) from the pituitary gland. It is unique among performance-enhancing peptides due to the presence of a reactive maleimidopropionic acid group that covalently links the peptide to free thiols on the surface of plasma proteins. Once conjugated, CJC-1295 remains active in the bloodstream for significantly longer than non-conjugated peptide-based drugs that are rapidly excreted. Conjugation of CJC-1295 to plasma proteins prevents its detection by top-down mass-spectrometry-based peptide screening protoc...
Hellyer PW, Bednarski RM, Hubbell JA, Muir WW.Baroreflex sensitivity (BS) was used to quantitatively assess the effects of halothane and isoflurane on the heart rate/arterial pressure relationship during steady-state (10 minutes) and dynamic pressure changes in adult horses. Arterial pressure was decreased in response to nitroglycerin or sodium nitroprusside and increased in response to phenylephrine HCl. Mean (+/- SEM) BS in awake horses was 28.9 +/- 2.6 and 13.2 +/- 2.0 ms/mm of Hg during steady-state decreases and increases in systolic arterial pressure (SAP), respectively. Halothane and isoflurane either significantly (P less than 0.0...
Hashimoto M, Nambo Y, Kondo T, Watanabe K, Orino K.In mammal circulation, ferritin-binding proteins (FBPs) are thought to be involved in clearance of circulating ferritin after complex formation with it through receptor-mediated uptake. However, there is no report on fetal FBP in fetal circulation. Although iron concentrations of fetal horse plasma were higher than those of adult horse plasma, plasma ferritin concentrations and ferritin-binding activities were found to be significantly lower in fetus than in adult. FBPs were purified from fetal or adult horse plasma on horse spleen ferritin-Sepharose 4B affinity column. Partially affinity-puri...
MacDonald KD, Hart KA, Davis JL, Berghaus LJ, Giguère S.Seizures are a common manifestation of neurological disease in the neonatal foal and are an important cause of morbidity and mortality in this population. Current antiepileptic options are effective, but often have undesirable adverse effects, short duration of action and high cost. Levetiracetam has an ideal safety and pharmacokinetic profile in multiple species, including the adult horse, and may be a safe and cost-effective alternative anticonvulsant in neonatal foals. Due to differences in drug disposition and clearance dosages in neonates, dosing recommendations in other species or adult ...
Snow DH, Munro CD, Nimmo MA.The effect of 11 weekly injections of nandrolone phenylpropionate (400 mg) was investigated by a crossover trial (2 training periods) in 6 Thoroughbred geldings undergoing training. A decrease in body weight and flank measurement occurred only during the first training period and was not modified by the anabolic steroid. Urinary nitrogen excretion was lower in the anabolic treated animals only in the first training period. Neither training nor training plus nandrolone phenylpropionate administration caused any marked alteration in blood biochemistry or haematology. A significant decrease in pl...
Gold JR, Grubb T, Court M, Villarino NF.Acetaminophen is a common analgesic and antipyretic drug used in human medicine and might be an alternative to nonsteroidal anti-inflammatory drugs for treating pain and pyrexia in foals. The pharmacokinetics and safety of differing doses of acetaminophen have not been investigated in foals. Objective: To determine the plasma pharmacokinetics and any changes in haematology and biochemistry profiles following oral administration of single doses of acetaminophen at 10, 20, and 40 mg/kg to foals. Methods: Randomised cross-over pharmacokinetic study. Methods: Six Quarter Horse (two colts and fou...
Fouché N, Oesch S, Gerber V, Richter H, Howard J, Peters LM.Sorbitol dehydrogenase (SDH) activity is one of the most sensitive and specific markers for hepatocellular injury in horses, but its reported lability makes it impractical for use in many clinical settings. To date, stability of SDH in equine samples has only been evaluated in a limited number of studies in serum samples of horses with activities within reference intervals. The objective of the study was to determine pre-analytical stability of equine SDH activity in heparinized plasma stored at different temperatures for up to 72 h. Twenty client-owned horses admitted to a veterinary teaching...
Rees WA, Harkins JD, Woods WE, Blouin RA, Lu M, Fenger C, Holland RE, Chambers TM, Tobin T.Amantadine is an antiviral agent effective against influenza A viruses. We investigated 1) the antiviral efficacy, 2) analytical detection, 3) bioavailability and disposition, 4) pharmacokinetic modelling and 5) adverse reactions of amantadine in the horse. In vitro, amantadine and its derivative rimantadine suppressed the replication of recent isolates of equine-2 influenza virus with effective doses (EDs) of less than 30 ng/ml. Rimantadine was more effective than amantadine against most viral isolates; we suggest a minimum plasma concentration of 300 ng/ml of amantadine for therapeutic effic...
Barakat SE, Ford EJ.The distribution of 5'-nucleotidase (5'-NT) and gamma-glutamyl transpeptidase (gamma-GT) is similar in the tissues of the sheep, calf and horse, except that there is relatively less gamma-GT in calf liver than in the liver of the other two species. The liver lesion produced by the oral administration of chloroform is similar in the three species and is accompanied by the release of 5'-NT into the plasma of the sheep and calf but not of the horse. Conversely, gamma-GT is released into plasma of the horse but not of the sheep or calf. This difference is not related to the tissue distribution of ...
Menendez MI, Phelps MA, Bertone AL.To the date, no reports exist of the pharmacokinetics (PK) of betamethasone (BTM) sodium phosphate and betamethasone acetate administered intra-articular (IA) into multiple joints in exercising horses. The purpose of the study was to determine the PK of BTM and HYD concentrations in plasma and urine after IA administration of a total of 30 mg BTM. Eight 4 years old Thoroughbred mares were exercised on a treadmill and BTM was administered IA. Plasma and urine BTM and HYD were determined via high performance liquid chromatography spectrometry for 6 weeks. Concentration-time profiles of BTM and H...
Soma LR, Gallis DE, Davis WL, Cochran TA, Woodward CB.Phenylbutazone (PBZ) was administered (8.8 mg/kg of body weight) every 24 hours for 5 consecutive days, orally for the first 4 days and IV on day 5. The half-life (t 1/2) after this daily administration was 6.2 hours and the volume of distribution was 0.152 +/- 0.014 L/kg; the bioavailability after oral administration was 91.8 +/- 2.5%. The plasma concentration of PBZ at experimental hour (EH) 24 (24 hours after the 1st oral dose) was 1.7 +/- 0.39 micrograms/ml and increased to 4.2 +/- 0.29 micrograms/ml at EH 48 (24 hours after the 2nd oral dose). Values at EH 72, 96, and 120 (24 hours after ...
Borchers A, Magdesian KG, Schenck PA, Kass PH.Vasopressin dysregulation occurs in critically ill human patients and in neonatal foals. Limited data about serial plasma vasopressin dynamics exist in sick neonatal foals. Objective: To evaluate serial plasma arginine vasopressin (AVP) concentrations in sick neonatal foals. Methods: Prospective, longitudinal clinical study. Methods: Plasma samples were collected from 7 healthy and 26 sick foals before and after initial fluid resuscitation and 12, 24, 36, 48 and 96 h after presentation. Foals with a modified sepsis score ≥ 11 were considered septic. Results: Admission AVP was increased in se...
