The study of blood in horses encompasses the examination of its components, functions, and its role in equine health and disease. Blood consists of various elements, including red blood cells, white blood cells, platelets, and plasma, each serving specific functions such as oxygen transport, immune response, clotting, and nutrient distribution. Analyzing blood parameters can provide insights into the physiological and pathological states of horses. Common blood tests in equine medicine assess parameters like hematocrit, hemoglobin concentration, and white cell counts to monitor health status, diagnose conditions, and guide treatment decisions. This page compiles peer-reviewed research studies and scholarly articles that explore the composition, function, and clinical applications of blood analysis in horses.
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...
Deichsel K, Aurich J, Parvizi N, Bruckmaier RM, Aurich C.The aim of the present study was to determine effects of lactation on basal LH and IGF-1 concentrations and on the LH response to a GnRH-analogue at different stages of the oestrous cycle in mares. A total of 17 cyclic Haflinger mares were included in the study. Experiments were performed on lactating mares in first postpartum oestrus, the subsequent early luteal phase, and second postpartum oestrus. Non-lactating mares were used in oestrus and early luteal phase. Blood samples were taken for 1 h at 15 min intervals. Mares were then injected with the GnRH-analogue buserelin (GnRHa; 5 microg i....
Pearson W, Boermans HJ, Bettger WJ, McBride BW, Lindinger MI.To characterize hematologic and clinical consequences of chronic dietary consumption of freeze-dried garlic at maximum voluntary intake in horses. Methods: 4 healthy sex- and age-matched horses. Methods: An initial garlic dose (0.05 g/kg, twice daily) was fed to 2 horses in a molasses carrier as part of their normal ration and was gradually increased to maximum voluntary intake (0.25 g/kg, twice daily) over 41 days. Dietary supplementation then continued for a total of 71 days. Two control horses were fed molasses with no garlic with their ration. Blood samples were collected weekly and analyz...
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+,...
Alhassan A, Pumidonming W, Okamura M, Hirata H, Battsetseg B, Fujisaki K, Yokoyama N, Igarashi I.With the aim of developing more simple diagnostic alternatives, a differential single-round and multiplex polymerase chain reaction (PCR) method was designed for the simultaneous detection of Babesia caballi and Babesia equi, by targeting 18S ribosomal RNA genes. The multiplex PCR amplified DNA fragments of 540 and 392 bp from B. caballi and B. equi, respectively, in one reaction. The PCR method evaluated on 39 blood samples collected from domestic horses in Mongolia yielded similar results to those obtained from confirmative PCR methods that had been established earlier. Thus, the single-roun...
Horteloup MP, Threlfall WR, Funk JA.The horse early conception factor (ECF) test is designed for qualitative determination of the ECF glycoprotein in the mare that has conceived. The objectives of this study were to determine the performance of the horse ECF test for the detection of the non-pregnant mare, and to determine the agreement among subjects or "readers" regarding the interpretation of the test. Blood samples from 60 mares were collected on Days 0, 5, 8, 11 and 18 following ovulation. Pregnancy status diagnosed with the ECF test was compared (2 x 2 table) to pregnancy status diagnosed by palpation per rectum and ultras...
Leleu C, Cotrel C, Courouce-Malblanc A.The relationships between V4 (the velocity for a blood lactate concentration of 4 mmol/litre) and V200 (the velocity for a heart rate of 200 bpm) and the performance indices of 223 healthy French trotters were analysed. They were divided into four age groups of three, four, five and six years and over, and into three performance groups (good, intermediate and poor performers) defined by the index of trot (ITR), an annual index of performance calculated by the national stud. V4 and V200 were assessed during the performance of a three-step standardised field exercise test, and four performance i...
Bergero D, Assenza A, Schiavone A, Piccione G, Perona G, Caola G.The aim of this work was to evaluate the changes in the concentrations, after two rides different for distance covered, of different amino acids in endurance horses. Blood samples have been collected from horses just before the start, at the top of a steep slope (819 m difference in height) and just at the end of a 32-km endurance ride. A second group, competing in a 72 km endurance ride, has also been sampled immediately before and after the race. In serum samples, the concentrations of alanine, arginine, asparagine, glycine, isoleucine, histidine, leucine, lysine, methionine, ornithine, phen...
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 ...
Manohar M, Goetz TE.The present study examined whether Thoroughbred horses performing strenuous exercise exhibit intrapulmonary arteriovenous shunting that may contribute to the observed arterial hypoxemia. Experiments were carried out on seven healthy, exercise-trained Thoroughbreds at rest, maximal exercise (galloping at 14 m/s on a 3.5% uphill grade for 120 s), and submaximal exertion (8 m/s on a 3.5% uphill grade for 150 s). Along with blood gas/hemodynamic parameters, intrapulmonary arteriovenous shunting was studied by injecting 15-microm-diameter microspheres, labeled with different stable isotopes, into t...
Heidmann P, Tornquist SJ, Qu A, Cebra CK.To determine whether epsilon-aminocaproic acid (EACA) administered IV affects hemostasis and fibrinolysis in clinically normal horses and ponies. Methods: 20 clinically normal adult horses and ponies. Methods: Blood samples were collected 24 hours before (baseline) and 1 and 5 hours after i.v. administration of a low dose (30 mg/kg) or high dose (100 mg/kg) of EACA. Platelet count, fibrinogen concentration, prothrombin time, partial thromboplastin time (PTT), D-dimer concentration, alpha2-antiplasmin activity, and thrombin-antithrombin complex concentration were measured. Values at 1 and 5 hou...
Kohn RA, Dinneen MM, Russek-Cohen E.The objectives of this study were to evaluate the potential for using blood urea N concentration to predict urinary N excretion rate, and to develop a mathematical model to estimate important variables of N utilization for several different species of farm animals and for rats. Treatment means (n = 251) from 41 research publications were used to develop mathematical relationships. There was a strong linear relationship between blood urea N concentration (mg/100 mL) and rate of N excretion (g x d(-1) x kg BW(-1)) for all animal species investigated. The N clearance rate of the kidney (L of bloo...
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...
Cambier C, Di Passio N, Clerbaux T, Amory H, Marville V, Detry B, Frans A, Gustin P.The purpose of this study was to determine the effect of regulating factors on the oxygen equilibrium curve (OEC) under standard conditions and then to calculate the oxygen extraction between arterial and jugular venous blood in healthy Standardbred horses. The results were compared to those previously obtained in humans and cattle, using the same experimental method. The partial oxygen pressure at 50% saturation of haemoglobin, measured under standard conditions (standard P50), was 24.8+/-2.0 (SD of mean) mmHg. This value was similar to the cattle standard P50 (25.0+/-1.4 mmHg, SD of mean) bu...
Farah AW, Hegazy NA, Romany MM, Soliman YA, Daoud AM.Twenty-three blood samples were used in this study; five were from five naturally infected horses with Babesia equi (B. equi), while eighteen were from asymptomatic horses with equine babesiasis from different localities in Egypt. All samples were subjected to microscopic examination, indirect fluorescent antibody test (IFA) and polymerase chain reaction (PCR). The carrier animals were microscopically detected in 7 out of 18 samples (38.8%) and in 9 of 18 by using IFA (50%), whereas PCR revealed that 14 samples were positive (78%). Two synthetic oligonucleotide primers, based on the B. equi me...
Magnarelli L, Fikrig E.Blood samples were collected from 98 horses suspected of having borreliosis or granulocytic ehrlichiosis in Connecticut and New York State, USA during 1985, 1995, and 1996. Serum antibodies to Borrelia burgdorferi were detected by an enzyme-linked immunosorbent assay (ELISA), based on whole-cell and recombinant antigens, in 82 (84%) horses. Of the 181 sera tested, 59% were positive, using whole-cell antigens, compared to 48% with protein (p)37 and 35% with VlsE antigens. An ELISA containing either of these fusion proteins can be used as an adjunct to general screening by an ELISA or immunoblot...
Legardinier S, Duonor-Cérutti M, Devauchelle G, Combarnous Y, Cahoreau C.Equine luteinizing hormone (eLH) and chorionic gonadotropin (eCG) are composed of identical alpha and beta polypeptide chains, but eCG subunits are much more heavily glycosylated and sialylated. Consequently, eCG exhibits a much longer half-life than eLH in blood. Recombinant eLH/CG, expressed in Sf9 and Mimic insect cells, were compared with one another and to the natural hormones eCG and eLH. Mimic cells are stably-transformed Sf9 cells, expressing five mammalian genes encoding glycosyltransferases involved in the synthesis of complex N-carbohydrate chains. Recombinant eLH/CG expressed in Mi...
de Moffarts B, Kirschvink N, Art T, Pincemail J, Lekeux P.The oxidant/antioxidant equilibrium of trained thoroughbred horses (n = 40) was assessed on three occasions during a period of three months under field conditions by blood antioxidant markers analysis, i.e. plasma ascorbic acid (AA), plasma antioxidant capacity of water-soluble components (ACW), whole blood (GSH) and oxidised (GSSG) glutathione, plasma alpha-tocopherol and beta-carotene, plasma antioxidant capacity of lipid-soluble components (ACL), red blood cell superoxide dismutase (SOD) and glutathione-peroxidase activity (GPx) and plasma trace-elements, i.e. selenium (Se), copper (Cu), zi...
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...
Lai SW, Lin JH, Lai SS, Wu YL.The characteristic ingredients of Ganoderma lucidum, such as polysaccharides, triterpenoids, nucleic acids and small proteins, have been found and proved to have many special pharmacological properties. Mice and rats have been extensively used to investigate the effects of G. lucidum. Experiments with horses as an animal model for investigating the effects of G. lucidum have never been reported. The purpose of this investigation was to understand the influence of G. lucidum feeding on blood biochemistry and immunocompetence in horses. Complete blood count (CBC) and blood biochemistry were surv...
Stoiber B, Zach C, Izay B, Windberger U.In situations where capillary perfusion in skeletal muscles is limited, changes in blood flow play an important role. Especially alterations in intrinsic erythrocyte factors like red cell aggregation and deformability would increase blood flow resistance. In our study we investigated whether whole blood and plasma viscosity influence exercise tolerance during submaximal training and whether a difference can be realized between trained and untrained standardbred trotters. Venous blood from 42 healthy adult trotters (20 horses at the beginning of their training and 22 well trained horses) was in...
Bettschart-Wolfensberger R, Freeman SL, Bowen IM, Aliabadi FS, Weller R, Huhtinen M, Clarke KW.Currently available sedatives depress cardiopulmonary function considerably; therefore, it is important to search for new, less depressive sedatives. The study was performed to assess duration and intensity of cardiopulmonary side effects of a new sedative, dexmedetomidine (DEX), in horses. Objective: To study pharmacokinetics and cardiopulmonary effects of i.v. DEX. Methods: Pharmacokinetics of 3.5 microg/kg bwt i.v. DEX were studied in a group of 8 mature (mean age 4.4 years) and 6 old ponies (mean age 20 years). Cardiopulmonary data were recorded in mature ponies before and 5, 10, 20, 30, 4...
Corley KT, Donaldson LL, Furr MO.Blood lactate concentration has been shown to be a useful clinical indicator in human patients, but has not been formally investigated in critically ill foals. Objective: To investigate the association of blood lactate with hospital survival, markers of cardiovascular status, metabolic acid base status, sepsis and systemic inflammatory response syndrome (SIRS). Methods: A database containing clinical, haematological, plasma biochemical and hospital outcome data on neonatal foals referred to an intensive care unit in 2000-2001 was analysed. Seventy-two foals for which arterial lactate was measu...
Jackson BF, Lonnell C, Verheyen KL, Dyson P, Pfeiffer DU, Price JS.Dorsal metacarpal disease (DMD) is a common problem in 2-year-old racehorses and results in loss of a significant number of days from training. Biochemical markers of bone cell activity measured early in the training season could have value for identifying 2-year-old Thoroughbred racehorses that develop DMD. Objective: To determine the association between serum concentrations of osteocalcin, the carboxyterminal propeptide of type I collagen (PICP) and the carboxyterminal cross-linked telopeptide of type I collagen (ICTP) measured early in the training season and the risk of DMD. Methods: Blood...
Krishnan A, Wilson A, Sturgeon J, Siedlecki CA, Vogler EA.A systematic study of water-air (liquid-vapor, LV) interfacial tension gamma(lv) of blood plasma and serum derived from four different mammalian species (human, bovine, ovine and equine) reveals nearly identical concentration-dependence (dgamma(lv)/dlnC(B); where C(B) is plasma/serum dilution expressed in v/v concentration units). Comparison of results to a previously-published survey of purified human-blood proteins further reveals that dgamma(lv)/dlnC(B) of plasma and serum is surprisingly similar to that of purified protein constituents. It is thus concluded that any combination of blood-pr...
Rossano MG, Schott HC, Murphy AJ, Kaneene JB, Sellon DC, Hines MT, Hochstatter T, Bell JA, Mansfield LS.Equine protozoal myeloencephalitis (EPM) is a serious neurological disease of horses in Americans. Most cases are attributed to infection of the central nervous system with Sarcocystis neurona. Parasitemia has not been demonstrated in immunocompetent horses, but has been documented in one immunocompromised foal. The objective of this study was to isolate viable S. neurona from the blood of immunocompetent horses. Horses used in this study received orally administered S. neurona sporocysts (strain SN 37-R) daily for 112 days at the following doses: 100/day for 28 days, followed by 500/day for 2...
Ohta M, Oku K, Mukai K, Akiyama K, Mizuno Y.To assess the clinical usability of propofol-ketamine anesthesia for internal fixation of fractures in racehorses, hemodynamics, blood pH and gases, and vital responses to the continuous intravenous anesthesia in 7 surgical cases were analyzed. The quality of induction with propofol was variable for individual horses. The vital signs reflecting circulation, breath, and anesthetic depth were kept good without any troubles throughout the surgery. Mean time from the end of anesthesia to standing up was prolonged, however recovery from anesthesia was calm and smooth in all cases. Propofol-ketamine...
Alexander SL, Irvine CH, Evans MJ.We used our nonsurgical technique for collecting pituitary venous blood to relate the dynamics of thyrotrophin-releasing hormone (TRH) secretion to the secretion patterns of both prolactin and thyrotrophin in periovulatory mares, either euthyroid (n = 5) or made hypothyroid by treatment with propyl-thiouracil (n = 5). Pituitary venous blood was collected continuously and divided into 1-min aliquots for 4 h. To test the effect of dopamine on the relationship between secretion patterns, sulpiride, a selective D2 receptor antagonist, was given i.m. after 2 h of sampling. Thorough testing of the m...
Macon EL, Harris P, Bailey S, Barker VD, Adams A.Controlling postprandial hyperinsulinaemia is important in insulin dysregulated (ID) horses to reduce the risk of laminitis. Objective: To evaluate postprandial insulin responses of ID versus non-insulin dysregulated (NID) horses to feedstuffs varying in nonstructural carbohydrate (NSC) and crude protein (CP). Methods: Randomised crossover. Methods: Eighteen adult mixed-breed horses (13.3 ± 2.2 years; 621 ± 78.8 kg) were individually fed [~1 g/kg body weight (BW)] specific feedstuffs within two crossover studies. Eight ID and eight NID were used in Study A, and 11 ID and 5 NID in Stud...
Silvestre-Ferreira AC, Cotovio M, Maia M, Queiroga F, Pires MJ, Colaço A.The Lusitano horse is an autochthonous Portuguese breed with a growing worldwide expansion. Our objective was to establish reference intervals for haematological parameters using the haematological cell counter LaserCyte (IDEXX). For this purpose, blood samples from 100 healthy adult horses (13 females and 87 males, ranging from 3 to 25 years of age) were analysed. The reference intervals were estimated following the ASVCP guidelines with the Reference Value Advisor software. The obtained reference intervals were 6.4-10.1 × 1012/L for red blood cells, 30.6-45.1% for haematocrit, 11.6-17.1 g/d...
Johnson CA, Thompson DL, Cartmill JA.The present experiment characterized the pituitary responsiveness to exogenous GnRH in the first 10 d after ovulation following commercially available deslorelin acetate implantation at the normal dosage for hastening ovulation in mares. Twelve mature, cyclic mares were assessed daily for estrus and three times weekly for ovarian activity starting May 1. Mares achieving a follicle at least 25 mm in diameter or showing signs of estrus were checked daily thereafter for ovarian characteristics. When a follicle >30 mm was detected, mares were administered either a single deslorelin acetate impl...
Dunlop CI, Steffey EP, Miller MF, Woliner MJ.Cardiopulmonary function was monitored in 6 non-medicated, healthy male horses, anesthetized with halothane or isoflurane in O2 at a constant dose (1.2 times the minimum alveolar concentration). Horses were exposed once to each anesthetic agent, and a minimum of 2 weeks separated anesthetic exposures. All horses were studied in left lateral recumbency, and ventilation was mechanically controlled to induce a PaCO2 of 35 to 45 mm of Hg and an inspiratory peak airway pressure of 18 to 22 cm of H2O. After 1 hour of horse preparation, constant conditions were begun. With duration of anesthesia, car...
Taddei L, Benoit M, Sukta A, Peterson J, Gaensslen RE, Negrusz A.In order to protect the integrity of horse racing in Illinois, a complex testing of urine and blood specimens collected post-race from winning and special designation horses is continuously conducted. The initial screening by immunoassays was followed by the confirmation on presumptive positive samples. Instrumental screening was also conducted. Perimortem and postmortem specimens and special exhibits (syringes, needles, etc.) were also analyzed. The administration of alkalinizing agents was detected by measuring the total plasma carbon dioxide concentration. The laboratory analyzed specimens ...
Moore RM, Muir WW, Bertone AL, Beard WL.Effects of low-flow ischemia and reperfusion of the large colon on systemic and colonic hemodynamic and metabolic variables were determined in horses. Twenty-four adult horses were randomly allocated to 3 groups: sham-operated (n = 6), 6 hours of ischemia (n = 9), and 3 hours of ischemia and 3 hours of reperfusion (n = 9). Low-flow ischemia was induced in groups 2 and 3 by reducing colonic arterial blood flow to 20% of baseline. Heart rate, arterial blood pressures, cardiac index, pulmonary artery pressure, right atrial pressure, and colonic blood flow were monitored. Arterial, mixed-venous, a...
Carlson GP, O'Brien MA.Anaerobic bacterial pneumonia with septicemia was diagnosed in 2 Thoroughbred racehorses referred with respiratory tract disease that had failed to respond to initial treatment with various antibiotics including penicillin and trimethoprim-sulfamethoxazole. Multiple anaerobic organisms, including Bacteroides spp and Fusobacterium spp, were isolated from blood and transtracheal aspirates obtained from both horses and from aspirates of cutaneous nodules obtained from 1 horse. The latter horse responded to metronidazole treatment followed by procaine penicillin G administration and regained its h...
Kelmer G, Martin-Jimenez T, Saxton AM, Catasus C, Elliot SB, Lakritz J.There are no reported studies evaluating the use of erythromycin for regional limb perfusion (RLP) in horses. Our hypothesis was that using the cephalic and saphenous veins for RLP will enable delivery of therapeutic concentrations of erythromycin to the distal limb. Nineteen healthy horses participated in the study. The cephalic, saphenous or palmar digital (PD) vein was used to perfuse the limb with erythromycin. Synovial samples were collected from the metacarpo/metatarso-phalangeal (MCP/MTP) joint and blood samples were collected from the jugular vein. Maximum concentration (C(max)) of ery...
Weiss DJ, Geor R, Smith CM, McClay CB.Echinocytes have been incriminated in the pathogenesis of exertional diseases in horses. To evaluate the hypothesis that echinocytes are dehydrated erythrocytes, we decreased blood sodium and potassium concentrations in 4 horses by administering furosemide (1.0 mg/kg of body weight, q 12 h) for 2 days and we monitored CBC, serum and erythrocyte sodium and potassium concentrations, and echinocyte numbers. Serum sodium concentration decreased progressively over the 48 hours of furosemide administration, then returned to near baseline concentration at 168 hours. A statistically significant decrea...
Estell KE, Knych HK, Patel T, Edman JM, Magdesian KG.To the authors' knowledge, there have been no studies evaluating the pharmacokinetics of chloramphenicol administered orally to horses at the currently recommended dose of 50 mg/kg PO q6 h for multiple days. The published antimicrobial susceptibility breakpoint is 8.0 ug/mL; it is unknown if this concentration is achievable at the recommended dose rate in horses. The aim of this prospective multi-dose pharmacokinetic study was to perform pharmacokinetic analysis of chloramphenicol after multiple doses. The authors hypothesize that the antimicrobial susceptibility breakpoint will not be reached...
Fortier J, Goachet AG, Julliand V, Deley G.In humans, cardiorespiratory responses are widely evaluated from field incremental exercise tests. On the contrary, equine exercise physiology faces a huge lack of oxygen consumption measurements (VO2) in field conditions due to technical concerns. The aim of this study was to test the effects of two incremental continuous field tests on cardiorespiratory responses in Standardbred trotters. The two protocols were realized at trot and ended when horses galloped. The tests started at 4.2 m/s (T1) and 6.4 m/s (T2), with speed increments of 1.4 m/s every 3 min for T1 and 0.8 m/s every 2 min for T2...
Targowski SP.Serum specimens from 12 sick and 20 normal horses were examined for levels of different classes of immunoglobulin (Ig) by a single radial immunodiffusion. The level of IgA in the sera of sick horses was about 50% lower than in the sera of normal horses. By contrast, the level of serum IgG was higher in sick than in normal horses. Phytohemagglutinin (PHA) responsiveness of blood lymphocytes showed transient suppression during the stage of severe diarrhea. The regaining of PHA responsiveness of lymphocytes was observed simultaneously with the recovery process. However, the responsiveness of lymp...
Urayama S, Arima D, Mizobe F, Shinzaki Y, Nomura M, Minamijima Y, Kusano K.Although hyperglycemia at admission with colic has been reported to have a poor prognosis, there is no report specifically about acute colitis with systemic inflammatory response syndrome (SIRS) in horses. In this study, we measured blood glucose (Glu), insulin (Ins), and cortisol (Cor) levels in 17 Thoroughbred racehorses diagnosed as having acute colitis with SIRS, and examined the relationship between time-dependent changes in Glu, Ins, and Cor and prognosis. Glu levels were high in 3 horses at admission, but thereafter no horses had persistently high Glu levels. There was no significant di...
Duncan SG, Meyers KM, Reed SM, Grant B.This experiment was designed to establish a model for the study of gastrointestinal disturbances as a result of prolonged endotoxin uptake in the horse. The hepatic portal vein of 7 horses was catheterized (through flank incisions) to give chronic hepatic portal infusions of lipopolysaccharide (LPS, endotoxin). Lipopolysaccharide was infused at a rate of 1 microgram/kg of body weight/hr for 24 hours. Two of the horses were infused with saline solution for 12 hours before LPS infusions were given. Lipopolysaccharide was shown to affect behavior and hematologic and coagulation values. The 1st ho...
Geor RJ, Weiss DJ, Smith CM.Hemorheologic alterations induced by incremental treadmill exercise were examined in 5 Thoroughbreds. Blood viscosity; PCV; RBC filterability, density gradient profile, and shape; serum and RBC electrolyte concentrations; and plasma total solids and lactate concentrations were measured before exercise, at treadmill speeds of 9 and 13 m/s, and 10 minutes after exercise. Exercise was associated with significant (P < 0.05) increases in PCV, blood viscosity, and plasma total solids concentration. After adjustment of PCV to 40% by adding or removing each horse's own plasma, blood viscosity ...
de Macêdo LB, Mouta AN, Araújo-Silva G, Urizar JTP, de Paula VV.Metamizole (MT), also known as dipyrone, is an analgesic and antipyretic drug labeled for use in humans and domestic animals in some countries. As with other drugs, the administration of MT in donkeys is based on studies carried out with horses. In the present report, we aimed to determine the pharmacokinetics of the two main metamizole active metabolites (N-methyl-4-aminoantipyrine [MAA] and 4-aminoantipyrine [AA]) following 10 (M ) and 25 mg/kg (M ) IV metamizole doses in Northeast Brazilian donkeys (n = 10). Blood was collected at predetermined times within over 48 h; MAA and AA plasma ...
Bazzano M, Giannetto C, Fazio F, Marafioti S, Giudice E, Piccione G.Hemostasis is a physiological process that prevents excessive blood loss and represents a protective mechanism at the time of delivery. Peripartum hemorrhage is a recurring hazardous condition to mare's health; therefore, we aimed to study mares' hemostatic profile to investigate whether physiological adjustments occur during late pregnancy and early postpartum. Fifteen pregnant mares have been monitored from the 34th week of pregnancy until the third week after foaling. Fifteen nonpregnant mares were used as control group. Jugular blood samples were analyzed for platelet count (Plt), prothrom...
McClay CB, Weiss DJ, Smith CM, Gordon B.Hematologic and rheologic changes were examined in 49 Thoroughbreds before and after competitive racing. Mean postrace values for RBC count, hemoglobin concentration, and PCV increased by 58 to 61%, whereas blood viscosity increased 2 to 3 times. Postrace echinocyte numbers were 162% greater than prerace values. Smaller, but statistically significant, changes were found for mean corpuscular hemoglobin concentration, red cell distribution width, plasma total protein concentration, total WBC count, neutrophil count, and lymphocyte count. Variables measured did not predict whether a horse was a b...
Ferreira-Dias G, Mateus L, Costa AS, Solá S, Ramalho RM, Castro RE, Rodrigues CM.Soon after ovulation, the newly formed corpus luteum (CL) starts secreting progesterone (P(4)), necessary for implantation. The CL, an ovarian transient endocrine organ, undergoes growth and regression throughout its life span. The objective of this study was to evaluate if caspase-3 mediates cell death in the equine cyclic luteal structures and relate it to luteal endocrine function. Blood and luteal tissue were collected during the breeding season after slaughter from 38 randomly assigned cycling mares. Luteal tissues were classified as corpora haemorrhagica (CH; n = 7); mid luteal phase cor...
Graves EA, Schott HC, Marteniuk JV, Refsal KR, Nachreiner RF.Limited information exists about changes in circulating thyroid hormone concentrations during prolonged endurance exercise in horses. Objective: To examine the effects of prolonged exercise on serum iodothyronine concentrations in horses performing endurance exercise of varying distances. Methods: Serum concentrations of iodothyronines were measured in horses before and after completion of 40, 56, 80 and 160 km endurance rides (Study 1); daily during a 5 day, 424 km endurance ride (Study 2); and before and for 72 h after completion of a treadmill exercise test simulating a 60 km endurance ride...
Gehlen H, Weichler A, Bubeck K, Ohnesorge B, Deegen E, Stadler P.The purpose of the present study was to investigate the effects of two different dobutamine concentrations on pulmonary artery wedge pressure (PAWP) and on mean systemic arterial blood pressure (MAP) in horses anaesthetized with isoflurane, after induction of general anaesthesia with xylazine, ketamine and diazepam. Eight healthy warm-blood horses were included in the study. Each horse was subjected to general anaesthesia twice with two different dosages of dobutamine, 3 and 5 microg/kg bw/min, being infused over 15 min, starting 50 min after induction of general anaesthesia (T(0)). The heart ...
Hamilton NA, Tammen I, Raadsma HW.Angiotensin converting enzyme (ACE) is essential for control of blood pressure. The human ACE gene contains an intronic Alu indel (I/D) polymorphism that has been associated with variation in serum enzyme levels, although the functional mechanism has not been identified. The polymorphism has also been associated with cardiovascular disease, type II diabetes, renal disease and elite athleticism. We have characterized the ACE gene in horses of breeds selected for differing physical abilities. The equine gene has a similar structure to that of all known mammalian ACE genes. Nine common single nuc...
Frank N, Sojka JE, Patterson BW, Wood KV, Bonham CC, Latour MA.To compare kinetics of the metabolism of very-low-density lipoprotein (VLDL) apolipoprotein B (apoB) before and after thyroidectomy in mares. Methods: 5 healthy adult mares. Methods: Thyroidectomy was performed in euthyroid mares. Kinetics of VLDL apoB metabolism were measured before and after thyroidectomy by use of a bolus IV injection of 5,5,5-2H3 (98%) leucine (5 mg/kg) and subsequent isolation of labeled amino acid from plasma and VLDL. Labeled leucine was quantified by use of gas chromatography-mass spectrometry. Production rate (PR), delay time, and fractional catabolic rate (FCR) were ...
Kunugiyama I, Ito N, Narizuka M, Kataoka S, Furukawa Y, Hiraga A, Kai M, Kubo K.Erythrocyte volumes of thoroughbred horses were measured. The volumes of splenectomized horses and sham-operated horses 2 hr after injection of 50Cr-tagged erythrocytes (at rest) and during maximal exercise were measured using the non-radioactive isotope 50Cr. Because splenic erythrocytes are released into circulation during exercise, it was estimated that the erythrocyte volumes of the sham-operated horses during maximal exercise are larger than those of the horses at rest. However, the erythrocyte volumes of the sham-operated horses at rest were about equal to those during maximal exercise. ...
Parry BW, McCarthy MA, Anderson GA, Gay CC.The influence of occlusive bladder width on blood pressure, measured indirectly using a doppler ultrasound technique at the middle coccygeal artery, was studied in 6 anesthetized horses. The relationship was investigated on tails with and without hair, and the optimum bladder width (BW)/tail girth (TG) ratio was determined for systolic pressure (SP) and diastolic pressure (DP), with the data grouped as unclipped tails (TT-1), clipped tails (TT-2), and both unclipped and clipped tails collectively (TTB). The optimum BW/TG ratios for SP and DP were 0.296 and 0.866 for TT-1, 0.376 and 1.156 for T...
Martin B, Silberzahn P.A significant decrease of CBG binding capacity in plasma of the mare throughout pregnancy was demonstrated using equilibrium dialysis and gel equilibration methods. As indicated with immunoelectrophoresis experiments, the pregnancy related fall of CBG binding capacity was linked to an actual decrease in blood CBG concentration. This result contrasts sharply with data on most other mammalian species, with the exception of the gestating rhesus monkey.
Fowden AL, Forhead AJ, Bloomfield M, Taylor PM, Silver M.Plasma glucagon concentrations were measured in chronically catheterized fetal ponies and their mothers between 260 days of gestation and term (approximately 335 days). Fetal alpha cell responses to arginine and variations in fetal glycaemia were also examined during late gestation. Immunoreactive glucagon was present in fetal plasma at 260 days of gestation and its concentration in utero increased after 320 days and then again at birth. Maternal plasma glucagon concentrations were higher after 300 days than earlier in gestation but were lower than the corresponding fetal value throughout the ...
Leiva M, Peña T, Armengou L, Cesarini C, Monreal L.Septicemia in humans is described as a leading cause of uveitis, which eventually can induce blindness. Objective: Uveal inflammatory findings could be related to sepsis severity in newborn foals and might be used as an indirect indicator for survival. Methods: Seventy-four septic foals, 54 nonseptic foals, and 42 healthy foals. Methods: Prospective observational clinical study. A detailed blinded, ophthalmic examination was performed by boarded ophthalmologists on all admitted newborn foals. Foals were grouped as septic (when blood culture resulted positive or the sepsis score was > or =14...
Weiss DJ, Evanson OA, McClenahan D, Fagliari JJ, Dunnwiddie CT, Wells RE.To determining whether inhibition of platelet aggregation prevents development of carbohydrate overload-induced alimentary laminitis. Methods: 22 healthy adult ponies. Methods: Acute laminitis was induced by oral administration of corn starch/wood flour to 16 ponies, 8 of which were treated with a synthetic analogue of the platelet fibrinogen receptor antagonist peptide (RPR) RGDS (arginine-glycine-aspartic acid-serine) 110885; 6 ponies served as negative controls. Blood was collected before and at 4, 8, 12, 24, 28, and 32 hours after administration of carbohydrate overload, and PCV, total pla...
Wagner AL, Urschel KL.To determine whether feeding-induced activation of translation initiation factors, specifically protein kinase B, ribosomal protein S6 kinase (S6K1), ribosomal protein S6 (rpS6), and eukaryotic initiation factor 4E binding protein 1, in horses is affected by age. Methods: 6 yearlings, six 2-year-old horses, and 6 mature horses. Methods: After an 18-hour period of feed withholding, horses consumed a high-protein meal (2 g/kg) at time 0 and 30 minutes (postprandial state) or continued to have feed withheld (postabsorptive state). Blood samples were collected for the duration of the experimental ...
