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.
Latson KM, Nieto JE, Beldomenico PM, Snyder JR.The most common cause of death as a direct result of colic is acute circulatory failure secondary to intestinal ischaemia. Early and accurate recognition of ischaemic bowel is essential to decrease complications and increase survival. Blood to peritoneal lactate values have been evaluated as a prognostic indicator, but lactate values characterised by type of lesion have not been reported. Objective: Plasma and peritoneal lactate values are higher in horses with intestinal ischaemia secondary to a strangulating obstruction (ISSO). Methods: Venous blood and peritoneal fluid were collected sequen...
Wichtel JJ, Grace ND, Firth EC.To examine the effect of intramuscular barium selenate on the blood selenium concentration of horses with marginal selenium status. Methods: Eighteen mares were assigned to one of six groups. The mares in groups 1-4 received barium selenate at 0.5, 0.75, 1.0 and 1.5 mg Se/kg, respectively, injected into the right pectoral muscle mass. The mares in group 5 received sodium selenate at 0.05 mg Se/kg orally at 8-week intervals. The mares in group 6 were left untreated. Blood samples were collected at 0, 1, 2, 5, 10, 30, 60, 90, 120, 180, 240, 300 and 360 days after the initial treatment for assay ...
Frank N, Sommardahl CS, Eiler H, Webb LL, Denhart JW, Boston RC.To evaluate glucose and lipid metabolism in healthy adult horses administered levothyroxine sodium (L-T4). Methods: 12 healthy adult mares. Methods: 8 horses received an incrementally increasing dosage of L-T4 (24, 48, 72, or 96 mg of L-T4/d) for weeks 1 to 8. Each dose was provide between 7 AM and 8 AM in the morning grain meal for 2 weeks. Four additional horses remained untreated. Serum concentrations of nonesterified fatty acids, triglyceride (TG), total cholesterol (TC), and very-low-density lipoprotein (VLDL) were measured and composition of VLDL examined in samples obtained between 8 AM...
Judy CE, Galuppo LD.To determine whether iatrogenic hemarthrosis of the metacarpophalangeal joint could be used as a model for temporary reversible joint pain in horses. Methods: 8 adult horses. Methods: Each horse was evaluated on a treadmill before and after injection of 1 metacarpophalangeal joint with 10 mL of autogenous blood. Horses were evaluated subjectively and objectively by use of a computerized force measurement system at intervals until lameness abated. The mean force difference between injected and noninjected limbs at all time periods after injection was compared with the difference between limbs a...
Yaralioglu-Gurgoze S, Cetin H, Cen O, Yilmaz S, Atli MO.Endometritis is an important factor in infertility. Free radicals play an important role in endometritis and we have investigated their possible role and scavenging systems in endometritis in purebred Arabian mares. The plasma concentration of malondialdehyde (MDA) and erythrocyte glutathione peroxidase (GPx) activity were compared in healthy mares and in mares with endometritis. The level of MDA was significantly increased while GPx activity was decreased in the mares with endometritis. Our findings support the notion that GPx is consumed by increased lipid peroxidation in purebred Arabian ma...
Kearns CF, McKeever KH, Roegner V, Brady SM, Malinowski K.Plasma concentrations of adiponectin and leptin were measured in 23 mature Standardbred mares (age: 10+/-3 years) and 12 weanling fillies (10 Quarter Horse/Belgian crossbreds and two Quarter Horses; aged: 4+/-3 months) to test the hypothesis that adipocytokines are proportional to adiposity in horses. Rump fat thickness was measured using B-mode ultrasound and percent body fat (% fat) calculated using a published formula for the estimation of fatness in horses. Plasma adiponectin and leptin were determined using radioimmunoassay. In the absence of purified equine adiponectin or leptin, results...
Sykes BW, Furr MO.The pathophysiology of endotoxaemia, a leading cause of death in the horse, is beginning to be understood in greater detail. Endotoxin may be absorbed into the systemic circulation in a number of different ways: most commonly the body's normal defense mechanisms are disrupted or bypassed, or the normal clearance mechanisms overwhelmed. Following this wide-spread effects are observed, although the most significant are seen in the cardiovascular system. Fever, arterial hypoxaemia and signs of abdominal pain are also common. With increased understanding of the disease new therapeutic agents have ...
Raidal SL, McTaggart C, Penhale J.To quantify absorption of colostral IgG by healthy neonatal foals and to test the hypothesis that delayed ingestion of macromolecules prolongs the duration of intestinal permeability to immunoglobulins (Ig) in newborn foals. Methods: Thirteen mixed breed foals. Methods: Foals were randomly assigned to two treatment groups, which were fed either a glucose-electrolyte solution or a commercial milk replacer for 12 h after birth, before being fed a known amount of colostral IgG. A control group was fed a known amount of colostral IgG from birth. The efficiency of IgG absorption was calculated foll...
Soma LR, Uboh CE, Guan F, Luo Y, Moate PJ, Boston RC, Driessen B.Hemoglobin-glutamer-200 (HBOC-200) is a hemoglobin (Hb)-based oxygen carrier (HBOC) comprising glutaraldehyde-polymerized bovine Hb. In this study, we sought to determine the pharmacokinetics of this first generation HBOC after IV infusion of 32.5 g of HBOC-200 solution in horses. Quantification of HBOC-200 in equine plasma and urine was performed using a method recently developed by our laboratory. The elimination from plasma was based on size distribution of the bovine Hb polymer. The decline of plasma concentration-time curve of HBOC-200 was described by a noninterchanging 2-compartmental m...
Menzies-Gow NJ, Bailey SR, Stevens K, Katz L, Elliott J, Marr CM.To measure plasma endothelin-1 (ET-1) concentrations and digital blood flow in clinically endotoxemic horses. Methods: 36 adult horses that underwent emergency celiotomy for primary gastrointestinal tract disease. Methods: On days 2 and 5 following surgery, Doppler ultrasonographic digital arterial blood flow measurements were obtained. Hematologic and biochemical analyses were performed, and plasma concentrations of ET-1 and endotoxin (lipopolysaccharide) were determined. A scoring system based on 9 clinical variables was used to assign horses to group B (quartile with greatest cumulative sco...
Sánchez Bruni SF, Fusé LA, Moreno L, Saumell CA, Alvarez LI, Fiel C, McKellar QA, Lanusse CE.The study of novel pharmacological strategies to control parasitism in horses is required since many parasite species have developed resistance to anthelmintic drugs. Objective: To evaluate the effects of piperonyl butoxide (PB) (a metabolic inhibitor) on the plasma availability and enantiomeric behaviour of oxfendazole (OFZ) given orally to horses, and to compare the clinical efficacy of OFZ given either alone or co-administered with PB in naturally parasitised horses. Methods: Fifteen naturally parasitised crossbred male ponies were allocated into 3 groups (n = 5) and treated orally as follo...
Collinder E, Nyberg F, Sanderson-Nydahl K, Gottlieb-Vedi M, Lindholm A.The opioid neuropeptide haemorphin-7 was measured, by immunoreactivity, in Standardbred horses during low-speed (7 m/s) and high-speed (10 m/s) endurance exercises, lasting 49-58 and 12-16 min respectively. In parallel, heart rate, muscle temperature and plasma lactate concentrations were measured. The profile of the low-speed exercise showed significantly increased heart rate after 10 min [154 beats per minute (bpm)]. After the exercise, muscle temperature (42.1 degrees C) and plasma lactate (4.8 mmol/l) were significantly increased. The profile of the high-speed exercise was comparatively ch...
Terada M, Momozawa Y, Komano M, Kusunose R, Sato F, Saito TR. The physiological indexes of the copulatory behavior of the stallion have not been investigated in detail and may differ from those of other species, such as humans and rats. In order to understand the breeding capability of various stallions, their behavior during copulation was observed, and heart rate (HR) and the plasma concentrations of norepinephrine (NA) and epinephrine (Ad) were measured sequentially for a total of 13 copulations carried out during 2 days. The mean HR at rest was 35.3 ± 0.9 beats per minute (b.p.m.) and it peaked during mounting (162.1 ± 5.4 b.p.m.). The HR a...
Luo Y, Uboh CE, Soma LR, Guan FY, Rudy JA, Tsang DS.A method for the simultaneous separation, identification, quantification and confirmation of the presence of 21 glucocorticoids (GCC) in equine plasma by liquid chromatography coupled with triple stage quadrupole tandem mass spectrometry (LC/TSQ-MS/MS) is described. Plasma sample augmented with the 21 GCC was extracted with methyl tert-butyl ether (MTBE) and analyzed by positive electrospray ionization. Desoxymetasone or dichlorisone acetate was used as the internal standard (IS). Quantification was performed by IS calibration. For each drug, one major product ion was chosen and used for scree...
Buff PR, Morrison CD, Ganjam VK, Keisler DH.Leptin is a protein hormone produced by adipose tissue that influences hypothalamic mechanisms regulating appetite and energy balance. In species tested thus far, including horses, concentrations of leptin increase as animal fat mass increases. The variables and mechanisms that influence the secretion of leptin are not well known, nor is it known in equine species how the secretion of leptin is influenced by acute alterations in energy balance, circadian patterns, and/or reproductive competence. Our objectives were to determine in horses: 1) whether plasma concentrations of leptin are secreted...
Donaldson MT, McDonnell SM, Schanbacher BJ, Lamb SV, McFarlane D, Beech J.The purpose of this study was to evaluate the variation in plasma adrenocorticotropic hormone (ACTH) concentration and dexamethasone suppression test (DST) results with season, age, and sex in healthy, pony mares (n=15) and pony stallions (n=14) living under semiferal conditions and horse mares (n=10) living at pasture. Plasma ACTH concentrations were measured in September 2002, and in January, May, and September 2003. DSTs were performed in January and September 2003. Plasma ACTH concentrations in September 2002 and September 2003 were similar and were significantly greater than in January an...
Hess TM, Kronfeld DS, Williams CA, Waldron JN, Graham-Thiers PM, Greiwe-Crandell K, Lopes MA, Harris PA.To compare effects of oral supplementation with an experimental potassium-free sodium-abundant electrolyte mixture (EM-K) with that of oral supplementation with commercial potassium-rich mixtures (EM+K) on acid-base status and plasma ion concentrations in horses during an 80-km endurance ride. Methods: 46 healthy horses. Methods: Blood samples were collected before the ride; at 21-, 37-, 56-, and 80-km inspection points; and during recovery (ie, 30-minute period after the ride). Consumed electrolytes were recorded. Blood was analyzed for pH, PvCO2, and Hct, and plasma was analyzed for Na+, K+,...
Vervuert I, Coenen M, Watermülder E.This study was conducted to evaluate the effects of oral tryptophan (Trp) supplementation on exercise capacity and metabolic responses in horses. Three horses had to perform an exercise test: a 15-min warm-up followed by a 60-min walk (1.7 m/s, W1), a 10-min trot (3.1 m/s, T1), a second 60-min walk (1.7 m/s, W2), a second 10-min trot (3.1 m/s, T2) and a final 30-min walk (1.7 m/s, W3) until the horses were unwilling to continue. The horses exercised on a treadmill at a 6% incline and with a constant draught load of 40 kg (0.44 kN). Two hours before exercise horses were given 50 g Trp (9.8-10.7...
Vervuert I, Coenen M, Zamhöfer J.This study was conducted to investigate the effects of draught load exercise on calcium (Ca) homeostasis in young horses. Five 2-year-old untrained Standardbred horses were studied in a 4-month training programme. All exercise workouts were performed on a treadmill at a 6% incline and with a constant draught load of 40 kg (0.44 kN). The training programme started with a standardized exercise test (SET 1; six incremental steps of 5 min duration each, first step 1.38 m/s, stepwise increase by 0.56 m/s). A training programme was then initiated which consisted of low-speed exercise sessions (LSE; ...
The Journal of physiologyMarch 24, 2005
Volume 565, Issue Pt 3 1019-1030 doi: 10.1113/jphysiol.2004.078469
Giussani DA, Forhead AJ, Fowden AL.In mammals, the mechanisms regulating an increase in fetal arterial blood pressure with advancing gestational age remain unidentified. In all species studied to date, the prepartum increase in fetal plasma cortisol has an important role in the maturation of physiological systems essential for neonatal survival. In the horse, the prepartum elevation in fetal cortisol and arterial blood pressure are delayed relative to other species. Hence, the mechanisms governing the ontogenic increase in arterial blood pressure in the horse fetus may mature much closer to term than in other fetal animals. In ...
van der Kolk JH, Rijnen KE, Rey F, de Graaf-Roelfsema E, Grinwis GC, Wijnberg ID.To determine whether increased glucose metabolism is the potential cause of the decreased plasma glucose curve determined after oral glucose tolerance testing in horses with lower motor neuron degeneration. Methods: 3 horses with signs suggestive of lower motor neuron degeneration, 1 horse with malignant melanoma with multiple metastases, and an obese but otherwise healthy horse. Procedures-Glucose metabolism was assessed by use of the hyperglycemic clamp and euglycemic hyperinsulinemic clamp techniques. Results: Mean rate of glucose metabolism of horses with lower motor neuron degeneration wa...
Edner A, Essén-Gustavsson B, Nyman G.During anaesthesia in the horse, muscle blood flow has been found to be reduced, possibly leading to hypoxia or ischaemia in the muscle. The aim of this study was to use the muscle biopsy and microdialysis techniques to determine whether long-term inhalation anaesthesia in laterally recumbent horses induces metabolic changes in gluteal muscle indicative of anaerobic metabolism. Muscle biopsies and plasma samples were taken from seven horses at the start and end of halothane anaesthesia. In six isoflurane-anaesthetised horses, given three pharmacological provocations (dobutamine, detomidine, ac...
Ferreira-Dias G, Claudino F, Carvalho H, Agrícola R, Alpoim-Moreira J, Robalo Silva J.The primary objective of this study was to evaluate the possible role of leptin, body weight and immune status on reproductive activity throughout the transition period from cyclicity to seasonal anestrus, during anestrus and resumption of ovarian activity in Lusitano mares. Mares in good body condition were monthly monitored throughout 2 years (10 mares in each year) for evaluation of their reproductive status by sequential ultrasonography and plasma progesterone determinations. On the second year, all mares were weighed. Progesterone and leptin were assayed by radioimmunoassay (RIA). Paramet...
Soma LR, Uboh CE, Luo Y, Guan F, Moate PJ, Boston RC.A compartmental model was used to describe the pharmacokinetics of dexamethasone (DXM) and changes in the plasma concentration of endogenous cortisone (COR) and hydrocortisone (HYD) following intravenous (i.v.) administration of DXM (0.05 mg/kg) in horses. Quantification of DXM, COR and HYD in equine plasma was achieved using liquid chromatography interfaced with triple spray quadrupole quantum tandem mass spectrometry (LC/TSQ-MS/MS). The median alpha (t(1/2alpha)), beta (t(1/2beta)), and gamma (t(1/2gamma)) half-lives were 0.33, 2.2, and 10.7 h respectively. The area under the DXM plasma conc...
Soraci AL, Tapia O, Garcia J.Flurbirpofen (FBP), a member of the 2-aryl propionate nonsteroidal anti-inflammatory drug class, has potent anti-inflammatory and analgesic properties. The commercial preparation is a racemic mixture of the R(-) and S(+) enantiomers of FBP. In this study, R(-) and S(+) FBP were used to investigate the metabolic chiral inversion. Each enantiomer was administered separately (0.25 mg/kg) and in a racemic mixture (0.5 mg/kg) intravenously to horses. Plasma and synovial concentration of each enantiomer was determined and the disposition of each was analyzed. After intravenous administration of R(-)...
Lee SJ, Lee KG.The inhibitory effect of aroma extracts isolated from dried soybeans, mung beans, kidney beans, and azuki beans on malonaldehyde (MA) formation from horse blood plasma oxidized with Fenton's reagent was determined by gas chromatography (GC) coupled with nitrogen-phosphorus detector (NPD). Aroma chemicals such as maltol, eugenol, benzyl alcohol, 1-octen-3-ol, butyrolactone, and 1-methyl-2-pyrrolidone, found in the aroma extracts of beans, were also examined for their inhibitory effect on the same system. Among the four aroma extracts tested, the aroma extract of soybeans exhibited the strongest...
Aleman M, Nieto JE, Carr EA, Carlson GP.This report describes 4 fatal cases of serum hepatitis associated with the administration of commercial plasma in the horse. Serum hepatitis in the horse is characterized by acute hepatic central lobular necrosis, and it has been associated with the administration of biological products of equine origin. None of these horses had a recent history of equine biologic-origin vaccination; however, they had received 1.5-5 L of commercial plasma, and in I horse, an additional 8 L of fresh blood. Acute, severe colic unresponsive to medical therapy, lethargy, or sudden death developed in these 4 horses...
Luo Y, Uboh CE, Soma LR, Guan F, Rudy JA, Tsang DS.This method describes the simultaneous separation, identification, quantification and confirmation of betamethasone (BTM) and dexamethasone (DXM) in equine plasma by liquid chromatography (LC) integrated with multidimensional tandem mass spectrometry. Analytes were directly extracted from equine plasma by methyl tert-butyl ether (MTBE). The residues were reconstituted with sample solvent. LC separation of the analytes was performed on a Hypercarb column using acetonitrile/water/formic acid (95:5:0.5, v/v/v) as the mobile phase. Sample screening, quantification and confirmation were performed i...
Benders NA, Dyer J, Wijnberg ID, Shirazi-Beechey SP, van der Kolk JH.To confirm whether the plasma glucose concentration curve obtained during oral glucose tolerance tests (OGTTs) in horses with equine motor neuron disease (EMND) is decreased, compared with that obtained in clinically normal horses, and determine whether that decrease is a result of defective glucose metabolism or intestinal glucose transport dysfunction. Methods: 8 horses with EMND and 44 matched control horses. Methods: Electromyography and OGTTs were performed in all 8 affected horses and 10 control horses. Intravenous GTTs (IVGTTs) were performed in 6 affected horses and another 11 control ...
Feige K, Ehrat FB, Kästner SB, Wampfler B.The goal of this study was to determine the effects of plasmapheresis on the behaviour, general condition, haematological, biochemical and coagulation variables of donor horses for 32 days following the procedure. Twenty millilitres of plasma/kg body weight were collected via plasmapheresis in six clinically healthy horses. The general behaviour and condition of the horses was not affected by the procedure. During plasmapheresis, there was a mild increase in the haematocrit, haemoglobin concentration and total erythrocyte and leucocyte counts (P < 0.01). The mean concentrations of total pro...
Andrews FM, Nadeau JA, Saabye L, Saxton AM.To measure total body water (TBW) content in horses, using deuterium oxide (D2O) dilution. Methods: Six 8- to 10-year-old healthy untrained mixed-breed horses, weighing (mean +/-SD) 503.4 +/- 64.0 kg. Methods: After a 12-hour nonfeeding period, 6 horses were given D2O (0.14 g/kg of body weight) via nasogastric tube. Blood samples were collected from a preplaced indwelling jugular vein catheter prior to and 1 to 8, 10, 12, 14, and 24 hours after administration of D2O. Blood samples were centrifuged immediately, and plasma was collected and stored at -70 C until analysis. The D2O content in plas...
Fielding CL, Magdesian KG, Meier CA, Rhodes DM.To describe the clinical and laboratory changes associated with the use of IV0.9% sodium chloride and a commercially available acetated fluid (CAF) to treat endurance horses requiring emergency medical treatment. Methods: Randomized, controlled clinical trial from 2007 to 2010. Methods: Emergency treatment centers of the Western States 100-mile (220 km) endurance ride. Methods: Twelve horses requiring emergency medical treatment in the form of IVfluids completed the study. Methods: Horses were assigned to either the 0.9% sodium chloride group (6 horses) or CAF group (6 horses) and received a t...
Sykes BW, Underwood C, McGowan CM, Mills PC.This study aimed to investigate the effect of diet and dose on the pharmacokinetics of omeprazole in the horse. Six horses received two doses (1 and 4 mg/kg) of omeprazole orally once daily for 5 days. Each dose was evaluated during feeding either a high-grain/low-fibre (HG/LF) diet or an ad libitum hay (HAY) diet in a four-way crossover design. Plasma samples were collected for pharmacokinetic analysis on days 1 and 5. Plasma omeprazole concentrations were determined by ultra-high pressure liquid chromatography-mass spectrometry. In horses being fed the HG/LF diet, on day 1, the area under...
Moore BR, Krakowka S, Mcvey DS, Cummins JM, Robertson JT.Protein and eicosanoid concentrations and procoagulant activity were determined in bronchoalveolar lavage fluid (BALF) from 32 Standardbred racehorses with inflammatory airway disease (IAD) and 6 control horses. Total protein, albumin and immunoglobulin G (IgG) concentrations were high (P < 0.05) in the BALF from horses with IAD, a finding consistent with exudation of plasma protein into the airway. Immunoglobulin A (IgA) concentrations also were increased (P < 0.05) which may signify local immunoglobulin production. Difference was not detected in prostaglandin E2 and 6-ketoprostaglandin...
Reijerkerk EP, Visser EK, van Reenen CG, van der Kolk JH.To compare the effects of IV administration of various doses of ovine corticotrophin-releasing hormone (oCRH) on plasma and saliva cortisol concentrations in healthy horses and determine whether an oCRH challenge test protocol is valid for use in adult horses. Methods: 24 healthy Warmblood horses. PROCEDURES-Each horse received oCRH in saline (0.9% NaCl) via IV administration at a dose of 0 (control treatment), 0.01, 0.1, or 1.0 Mg/kg (6 horses/group). Jugular blood and saliva samples were collected simultaneously 15 minutes before and immediately prior to injection (baseline); data from these...
Garcia P, Pinètre J, Morel S, Jaubert M, Deruy X, Perot I, Delcourt V, Loup B, Popot MA, Bailly-Chouriberry L.Bisphosphonates are prohibited drugs according to Article 6 of the International Agreement on Breeding, Racing and Wagering of the International Federation of Horseracing Authorities (IFHA) and the International Equestrian Federation (FEI). These compounds are used for the treatment of lameness, navicular and bone diseases in horses and are divided into two groups: non-nitrogen-containing bisphosphonate drugs (e.g. clodronic acid) and nitrogen-containing bisphosphonate drugs (e.g. zoledronic acid). Their hydrophilic properties and the high affinity for the bone matrix make the control of their...
Burrows GE, MacAllister CG, Beckstrom DA, Nick JT.The plasma concentrations and pharmacokinetics of rifampin disposition were determined after a single IV, IM, or oral dose of 10 mg/kg of body weight and an oral dose of 25 mg/kg. The overall elimination rate constants per minute were similar for the 10 mg/kg dose (0.0021 +/- 0.0004, IV; 0.0017 +/- 0.0002, IM; and 0.0023 +/- 0.0006, orally). The apparent bioavailability was moderate to low for IM and oral administrations (59.8% +/- 3.2% and 39.5% +/- 5.0%, respectively). The rate of absorption was most rapid for oral administration with an absorption half-life of 249.7 +/- 71.6 minutes as comp...
Sams R, Gerken DF, Ashcraft SM.The pharmacokinetics and urinary excretion of ketoprofen in six healthy mares after the first and last of five daily intravenous doses of 2.2 mg of ketoprofen per kg body weight were investigated using a high-performance liquid chromatographic (HPLC) method for determining plasma and urinary ketoprofen concentrations. Plasma ketoprofen concentrations declined triexponentially after each dose with no significant differences in plasma concentrations or pharmacokinetic parameter values between the first and last doses. The harmonic mean of the terminal elimination half-life of ketoprofen after th...
Agüera EI, Rubio MD, Vivo R, Santisteban R, Muñoz A, Castejón F.A study was performed on Andalusian horses in order to assess the response of heart rate and various blood parameters to training. Two tests were performed, at two and four months of training respectively. Exercise schedules were of increasing intensity, over a distance of 1000 meters. Speed was progressively increased, from 4 m/s to 8.5 m/s, over four exercise stages. In both tests, a recovery period of 5 min followed each stage. Sample collection (by puncture of the external jugular vein) was performed with the animals at rest, within the first minute after each exercise stage, and at 10, 15...
Palmer E, Jousset B.Following an initial observation period of 13 days when plasma progesterone levels were determined, synchronization of oestrus and ovulation was investigated in thirty-three mares treated with a prostaglandin analogue ('Equimate') and HCG. Two courses of treatment were given 8 days apart and each consisted of a single intramuscular injection of Equimate (250 mug) followed 6 days later by an intramuscular injection of HCG (2500 i.u.). The first course was designed to remove all luteal tissue and to induce ovulation of any follicles that developed in response to the withdrawal of progesterone. T...
Donadeu FX, Ginther OJ.The role of the number of follicles and circulating immunoreactive inhibin in the decrease in plasma FSH concentrations that occurs during development of a follicular wave was studied in mares. All follicles > or = 6 mm in diameter were ablated by ultrasound-guided transvaginal aspiration of follicular fluid on day 10 after ovulation. During the subsequent wave, all follicles, the three largest follicles (three follicle group), the largest follicle (single follicle group) or no follicles were retained and the remaining follicles were ablated before they reached > 10 mm in diameter (n = 1...
Pass MA, Mogg TD.Amitraz and its active metabolite BTS27271 were given intravenously to ponies and sheep at equimolar doses of 1 mg/kg and 0.68 mg/kg, respectively, and the plasma concentrations of amitraz and BTS27271 estimated at various times thereafter. Amitraz was hydrolysed to BTS27271 in both species. Amitraz was undetectable in sheep plasma after approximately 5 min but persisted in the plasma of ponies for at least 90 min. The persistence of unmetabolized amitraz in ponies may have implications for the toxicity of amitraz in that species. The primary and secondary disposition half-lives of amitraz in ...
Allen BV, Blackmore DJ.The relationship between paired plasma and serum viscosity measurements and plasma proteins, including fibrinogen, were compared in 106 horses with both normal and abnormal serum protein levels. There is a highly significant positive correlation between serum viscosity and total serum proteins and total globulin levels. The difference between plasma and serum viscosity correlated well with clottable fibrinogen concentration. Albumin levels showed a negative correlation with plasma and serum viscosity, globulins and fibrinogen. Simultaneous estimation of serum and plasma viscosity improves the ...
Tsuchiya T, Noda R, Ikeda H, Maeda M, Sato F.Pituitary pars intermedia dysfunction (PPID) is an endocrine disorder the clinical signs of which include infertility, but few reports have examined the relationship between PPID and reproductive performance in broodmares. Objective: Broodmares with infertility of unknown etiology were screened for PPID using baseline endogenous plasma ACTH concentrations, and its relationship with subsequent reproductive performance was analyzed. Methods: Sixty-seven Thoroughbred broodmares. Methods: Adrenocorticotropic hormone concentrations were measured in autumn. The broodmares were divided into 3 groups ...
Guan F, You Y, Li X, Robinson MA.Bioactive peptides possess pharmacological effects and can be illicitly used in sports. To deter such misuse, an untargeted method using high resolution mass spectrometry (HRMS) has been developed for comprehensive detection of multitudinous exogenous peptides in equine plasma and urine. Forty-four peptides were extracted using mixed-mode solid-phase extraction (SPE) from plasma and urine, separated with a hydrophilic interaction liquid chromatography (HILIC) column, and detected on an HRMS instrument. Ammonium formate as a mobile phase additive had effects on HILIC retention and charge state ...
Kędzierski W, Kusy R, Kowalik S.The aim of this study was to evaluate the relationship between plasma leptin and lipid levels in breeding mares and their newborn foals. The study was conducted on 17 Polish cold-blood mares and their newborn foals. The mares were divided into two groups, according to the course of delivery. These groups were seven mares which had a normal delivery and 10 mares which had required veterinary intervention during their delivery. Blood samples were taken from the jugular vein of both the mares and their foals. The blood samples were taken within 30 min after delivery, as well as on four successive...
Vervuert I, Coenen M, Zamhöfer J.This study was conducted to investigate the effects of draught load exercise on calcium (Ca) homeostasis in young horses. Five 2-year-old untrained Standardbred horses were studied in a 4-month training programme. All exercise workouts were performed on a treadmill at a 6% incline and with a constant draught load of 40 kg (0.44 kN). The training programme started with a standardized exercise test (SET 1; six incremental steps of 5 min duration each, first step 1.38 m/s, stepwise increase by 0.56 m/s). A training programme was then initiated which consisted of low-speed exercise sessions (LSE; ...
Giorgi M, De Vito V, Poapolathep A, Rychshanova R, Sgorbini M, Owen H.Flupirtine (FLU) is a non-opioid analgesic drug, with no antipyretic or anti-inflammatory effects, used in the treatment of a wide range of pain states in human beings. It does not induce the side effects associated with the classical drugs used as pain relievers. The aim of this study was to evaluate the pharmacokinetic profiles of FLU after IV and PO administration in healthy horses. Six mixed breed adult mares were randomly assigned to two treatment groups using an open, single-dose, two-treatment, two-phase, paired, cross-over design (2 × 2 Latin-square). Group 1 (n = 3) received ...
Lees P, Creed RF, Gerring EE, Gould PW, Humphreys DJ, Maitho TE, Michell AR, Taylor JB.Five matched pairs of horses were used to investigate the effects of phenylbutazone on a range of physiological, biochemical and haematological variables. The drug was given by mouth daily for 15 consecutive days at the manufacturer's recommended dose rates to one group of horses (Group A); the second group (Group B) received equivalent doses of a placebo. For some of the measured parameters, significant changes were recorded in both groups, indicating background instability. Significant decreases in serum total protein, albumin, plasma pH, viscosity and magnesium, and an increase in albumin: ...
Brosnan RJ, Steffey EP, Escobar A, Palazoglu M, Fiehn O.To evaluate whether guaifenesin can prevent adverse anesthetic induction events caused by propofol and whether a guaifenesin-propofol induction combination has brief cardiovascular effects commensurate with rapid drug washout. Methods: 8 healthy adult horses. Methods: Guaifenesin was administered IV for 3 minutes followed by IV injection of a bolus of propofol (2 mg/kg). Additional propofol was administered if purposeful movement was detected. Anesthesia was maintained for 2 hours with isoflurane or sevoflurane at 1.2 times the minimum alveolar concentration with controlled normocapnic ventila...
Waller A, Lindinger MI.Sodium acetate (NaAcetate) has received some attention as an alkalinizing agent and possible alternative energy source for the horse, however the effects of oral administration remain largely unknown. The present study used the physicochemical approach to characterize the changes in acid-base status occurring after oral NaAcetate/acetic acid (NAA) administration in horses. Methods: Jugular venous blood was sampled from 9 exercise-conditioned horses on 2 separate occasions, at rest and for 24 h following a competition exercise test (CET) designed to simulate the speed and endurance test of 3-da...
Sneddon JC, van der Walt JG, Mitchell G.This study set out to investigate tolerance of the body water pool to short-term water deprivation in horses and, in particular, to assess whether feral horses from the Namib Desert showed tolerance to dehydration superior to Transvaal. Hydration status was compared in six feral horses from the Namib Desert and in six Boerperd farm horses under conditions of normal hydration and after 72 h of dehydration. Under normal hydration, the two groups did not differ significantly in water intake, plasma sodium and potassium concentrations, plasma osmolality, hematocrit, total plasma protein, body wate...
Bröjer JT, Nostell KE, Essén-Gustavsson B, Hedenström UO.To determine whether repeated oral administration of glucose and leucine during the period immediately after intense exercise would increase the release of insulin and thereby enhance glycogen synthesis in horses. Methods: 12 Standardbred horses. Methods: In a crossover study design, after glycogen-depleting exercise, horses received oral boluses of glucose (1 g/kg at 0, 2, and 4 hours) and leucine (0.1 g/kg at 0 and 4 hours) or boluses of water (10 mL/kg at 0, 2, and 4 hours; control treatment). Blood samples for determination of glucose, insulin, and leucine concentrations were collected pri...
Wang J, Qiu J, Xiao H, Gong X, Sun P, Li J, Zhang S, Cao X.The pharmacokinetic properties of three formulations of vitacoxib were investigated in horses. To describe plasma concentrations and characterize the pharmacokinetics, 6 healthy adult Chinese Mongolian horses were administered a single dose of 0.1 mg/kg bodyweight intravenous (i.v.), oral paste, or oral tablet vitacoxib in a 3-way, randomized, parallel design. Blood samples were collected prior to and at various times up to 72 hr postadministration. Plasma vitacoxib concentrations were quantified using UPLC-MS/MS, and pharmacokinetic parameters were calculated using noncompartmental analysis...
Pérez R, Godoy C, Palma C, Muñoz L, Arboix M, Alvinerie M.A study was done to compare plasma disposition kinetics and the fecal elimination profile of doramectin (DRM) after oral or intramuscular (IM) administration in horses. Ten clinically healthy horses, 328-502 kg body weight (bw), were assigned to 2 experimental groups of 5 horses each. Group 1 was treated with an oral dose of 0.2 mg DRM/kg bw, while Group 2 was treated with 0.2 mg DRM/kg bw by IM route. Blood and fecal samples were collected at different times between 0.5h and 60 days post-treatment. After plasma and fecal drug extraction and derivatization, samples were analysed by high perfor...
Muñoz A, Santisteban R, Rubio MD, Vivo R, Agüera EI, Escribano BM, Castejón FM.The physiological and metabolic adaptations to exercise of the Andalusian horse seem to differ slightly from those found in other breeds. The authors studied the locomotor adaptation of 18 Andalusian horses to a training programme in relation to anaerobic energy metabolism, efficacy of the training programme, and changes associated with the onset of fatigue. They also tried to find out if these changes had become diminished by training. Several locomotor variables during trotting and galloping were determined and plasma lactate concentrations were measured before training and after two trainin...
Sanz MG, Schnider DR, Mealey KA.Relative to other species, horses seem particularly susceptible to oxidative stress. Plasma albumin plays an important role in preventing oxidative damage, in part due to its methionine (MET) content. Equine albumin is highly unusual in that it contains no MET residues. Whether or not this causes deficient antioxidant capacity in equine plasma relative to that of other species has not yet been explored. The objective of this study was to compare the redox status of equine (no MET) to that of bovine (moderate amount of MET) plasma. Plasma was collected from healthy, nonpregnant Quarter Horse ma...
Brewer BD, Clement SF, Lotz WS, Gronwall R.The glomerular filtration rate (GFR) was estimated in eight full-term neonatal foals by the single injection inulin plasma clearance method at two days of age, the continuous infusion plasma and urinary clearance methods at three days of age, and the 12-hour endogenous creatinine clearance method at four days of age. The effective renal plasma flow (ERPF) was estimated simultaneously by the single injection para-aminohippuric acid (PAH) plasma clearance method in the eight two-day old foals and the continuous PAH infusion plasma and urinary clearance method in the eight three-day old foals. Th...
Davis JL, Gardner SY, Jones SL, Schwabenton BA, Papich MG.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...
Park SC, Yun HI.The pharmacokinetic properties of norfloxacin-glycine acetate (NFLXGA) were determined in six horses following a single intravenous (i.v.) and intramuscular (i.m.) dose of 4 mgkg(-1) body weight. Following i.v. and i.m. administration, the plasma drug concentrations were best fitted by an open two-compartment model with a rapid distribution phase. After i.v. NFLXGA administration, the distribution (t(1/2alpha)) and elimination half-life (t(1/2beta)) were 0.42 (0.05) and 5.44 (1.36)h. The volume of distribution of NFLXGA at steady state (Vd(ss)) was 2.19 (0.53) Lkg(-1). After NFLXGA i.m. admini...
