The physiology of horses encompasses the study of the biological functions and processes that occur within the equine body. This includes the examination of various systems such as the cardiovascular, respiratory, musculoskeletal, digestive, and nervous systems. Understanding equine physiology is essential for comprehending how horses adapt to different environmental conditions, perform physical activities, and respond to health challenges. Research in this field often focuses on the mechanisms of energy metabolism, thermoregulation, and muscle function during exercise, as well as the physiological responses to stress and disease. This page compiles peer-reviewed research studies and scholarly articles that explore the diverse aspects of equine physiology, providing insights into the biological processes that support the health and performance of horses.
O'Callaghan MW, Hornof WJ, Fisher PE, Rabbe OG.This study describes the development of a radioaerosol technique for horses using 99mtechnetium-DTPA (diethylenetriaminepentacetate). In 24 normal, adult horses, very satisfactory ventilation images were obtained with the technique. Four-minute administrations of the aerosol resulted in a mean uptake of radioactivity in the lung fields of 3.02 mCi, with mean maximum counts (+/- sd) of 159,800 +/- 75,000 per camera field. The mean clearance half-time for the 99mtechnetium-DTPA from the lung fields was 55.6 +/- 14.2 mins which is very similar to figures obtained for normal human and dog lungs. T...
Juneja RK, Gahne B, Stratil A.Pig, horse and dog plasma proteins, separated by horizontal polyacrylamide gel electrophoresis (pH 9.0) and electrophoretically transferred to nitrocellulose membranes, were tested for cross-reaction with antiserum to human plasma alpha 1B-glycoprotein (alpha 1B). The results showed that one previously reported polymorphic plasma postalbumin in each of these species (pig PO2, horse Xk and dog Pa protein) was homologous to human plasma alpha 1B. In the light of the previously known genetic linkages in these species, this implied: (1) alpha 1B gene is close linked to Phi, Pgd and Hal (halothane ...
Blaze CA, Robinson NE.Apneic oxygenation was studied in six ponies for 30 minutes, and six horses for 10 minutes. Arterial blood was sampled at regular intervals for measurement of oxygen and carbon dioxide tensions (PaO2 and PaCO2) and calculation of alveolar-arterial oxygen tension difference (PAO2-PaO2). In both groups of animals, PaO2 decreased rapidly during the first 3 minutes of apnea, then more slowly. Although the mean value was above 100 mmHg at 10 minutes, there was considerable inter-animal variability. Before apnea, PAO2-PaO2 was slightly, but not significantly, larger in horses than in ponies and incr...
Powers SK, Beadle RE, Thompson D, Lawler J.The purpose of these experiments was to examine the temporal pattern of arterial carbon dioxide tension (PaCO2) to assess the relationship between alveolar ventilation (VA) and CO2 return to the lung at the onset and offset of submaximal treadmill exercise. Five healthy ponies exercised for 8 min at two work rates: 50 m/min 6% grade and 70 m/min 12% grade. PaCO2 decreased (P less than 0.05) below resting values within 1 min after commencement of exercise at both work rates and reached a nadir at 90 s. PaCO2 decreased maximally by 2.5 and 3.5 Torr at the low and moderate rate, respectively. Aft...
Sirois J, Betteridge KJ, Goff AK.The outcome of 23 collections and reinsertions of conceptuses on Days 10.5-13.5, 4 transfers of Day-10.5, and 13 transfers of Day-6.5 embryos (ovulation = Day 0) was monitored in 30 mares. Blood samples were taken before and after each procedure to measure plasma 15-keto-13,14-dihydroprostaglandin F-2 alpha (PGFM), and then daily for progesterone determinations. Mares were also subjected to daily teasing for detection of oestrus, and to uterine ultrasonography for tracing the development of the conceptus. After the reinsertions, 12/23 conceptuses were detectable immediately after the procedure...
McDowell KJ, Sharp DC, Grubaugh W.Eight ovariectomized pony mares were used to test the effect of various doses of progesterone (0, 50, 150, 450 mg/day, in oil, i.m., for 10 days) on progesterone and LH in the peripheral circulation, and on total protein and uteroferrin in uterine secretions. Progesterone increased uteroferrin, but there were no differences amongst doses of progesterone. Progesterone treatment decreased LH, and tended to increase total protein. Eighteen ovariectomized mares were given vehicle, oestradiol (10 mg/day, in oil, i.m.), progesterone or progesterone + oestradiol for 28 days. Both the last two steroid...
Okólski A, Babusik P, Tischner M, Lietz W.Comparisons were made between 2 methods of oocyte recovery from the ovarian follicles of slaughtered mares: 500 oocytes (3 per mare) were obtained by aspiration of follicular fluid from ovaries of 162 mares, and 120 oocytes (8 per mare) by isolation and rupture of follicles from ovaries of 14 mares. In the oocytes recovered after rupture of follicles, 89.2% were morphologically unchanged, in comparison to 29.3% obtained by aspiration of follicular fluid. Stallion spermatozoa capacitated in vitro were tested on zona-free hamster oocytes. The stallion spermatozoa were washed in TCM-199 and prein...
Le Goff D, Nouvelot A, Fresnel J, Silberzahn P.1. Plasma lipoproteins from six thoroughbred horses were separated by density gradient ultracentrifugation. For each sample, lipoprotein bands were visualized by means of a prestained plasma control and characterized by electrophoretic, chemical and morphological analysis. 2. Very low density lipoproteins (VLDL) were isolated at d less than 1.018 g/ml. 3. Two clearly resolved bands were detected in the low density lipoprotein fraction (LDL). The density limits were evaluated as follows: LDL1(1.028 less than d less than 1.045 g/ml) and LDL2(1.045 less than d less than 1.070 g/ml). Marked differ...
Crump A, Donaldson WL, Miller J, Kydd JH, Allen WR, Antczak DF.Antibodies to fetal major histocompatibility complex (MHC) antigens are routinely detected in the serum of pregnant mares some 2-4 weeks after formation of the endometrial cups at Day 36-38 after ovulation. Several experimental approaches were taken to determine whether paternal MHC antigens are expressed on horse placental tissues. First, absorption of anti-paternal MHC antisera with a large volume of endometrial cup cells removed antibody activity in only 2 of 4 experiments. Second, repeated immunization of horses with endometrial cup tissue recovered from a mare on Day 47 of pregnancy faile...
Stewart F, Leigh SE, Thomson JA.Complementary (c)DNA libraries have been made from horse pituitary gland and endometrial cup tissues with the aim of isolating the genes for the horse gonadotrophins (FSH, LH and CG) and growth hormone (GH). Southern (DNA) and Northern (RNA) blotting techniques were used to demonstrate that several heterologous (human and ovine) cDNA probes would be adequate for isolating the horse genes. A human cDNA probe was then used to isolate the horse gonadotrophin alpha-subunit cDNA from the pituitary and endometrial cup libraries. The nucleotide sequences from both tissue sources were identical, there...
Brugère H, Castellani G, Boxebeld A, Wolter R.A re-entrant cannulation of the digestive tract was performed in Equidae (ponies and donkeys) between the distal extremity of the ileum and the base of the caecum. The operative technique was conceived to avoid risks of infection of the peritoneal cavity: the openings of the ileum and of the caecum were achieved only after the closure of the abdominal wall incision. Two donkeys were still alive ten months after the operation. This method can provide a convenient model for digestibility studies in Equidae, particularly for assessment of the pre-caecal digestibility.
Vogelsang MM, Kraemer DC, Potter GD, Stott GG.Oocytes recovered by follicular aspiration were evaluated by light and transmission electron microscopy. Of the 22 oocytes, 4 exhibited characteristics of degeneration, and the remaining 18 were in various stages of meiotic development. Of the non-degenerate oocytes, 14 were in the germinal vesicle stage, 2 had undergone nuclear membrane disintegration, 1 displayed chromosomes in late metaphase I-early anaphase I, and 1 oocyte was in the process of extrusion of the first polar body. Although some oocytes retained complete cumulus cell investments, oocytes were predominantly enclosed only by th...
Hyland JH, Wright PJ, Clarke IJ, Carson RS, Langsford DA, Jeffcott LB.In Exp. 1, 30 Standardbred mares in deep seasonal anoestrus were divided into 3 equal groups and treated with 0, 50 (G50) or 100 (G100) ng GnRH kg-1h-1 for 28 days via osmotic minipumps. Ovulation occurred in 0/10, 3/10 and 7/10 mares respectively (P less than 0.05). Plasma GnRH profiles (Days -6, 0, 2, 6, 12, 20, 28 and 34 relative to pump insertion) were dose-dependent (P less than 0.01) and peaked on Day 12 of infusion. Mean daily plasma LH concentrations were biphasic in treated mares that ovulated, with LH peaks occurring around Day 6 and Days 16-20. By contrast, in treated mares that did...
Goff AK, Pontbriand D, Sirois J.In Exp. 1, 4 mares were given oxytocin intravenously (10 i.u./500 kg body wt) daily between Days 9 and 14 (Day 0 = day of ovulation) when pregnant and on Days 9-14, 16, 18, 20 when non-pregnant (not inseminated). In the non-pregnant mares the increase in plasma PGFM response to oxytocin was greater at Day 13 (235 +/- 54 pg/ml) than at Day 11 (113 +/- 38 pg/ml; P less than 0.05) and was maximum at Day 16. However, these animals did not return to oestrus and plasma progesterone did not fall below 4 ng/ml. There was no significant increase in response to oxytocin between Days 9 and 14 in the preg...
Silver M, Fowden AL, Knox J, Ousey JC, Franco R, Rossdale PD.The effects of insulin-induced hypoglycaemia on plasma catecholamines, cortisol and metabolites have been examined in newborn and 7-14-day-old foals. The fall in plasma glucose elicited by the highest dose of insulin (1.0 i.u./kg) given to the neonates was slower in onset and less severe in effect than 0.5 i.u./kg in the older foals. There was a significant inverse correlation between the concentrations of glucose and adrenaline (but not noradrenaline) in plasma once the glucose level had fallen below 2 mmol/l; the adrenergic response to hypoglycaemia was greater in the 7-14-day-old foals than...
Moore EN, Spear JF.We tested the multiple-wavelet hypothesis by studying the initiation and maintenance of atrial fibrillation in normal mules, horses, cows, calves, and goats. Persistence of atrial fibrillation in animals with a large atrial mass was compared with results in adult goats and calves having a smaller atrial mass. Atrial stimulation in clinically normal cows, mules, calves, and goats was accomplished using an intra-atrial stimulating catheter with rapid atrial pacing (30/s). Once initiated, atrial fibrillation persisted for 95,120,125 min, 3 days, and 8 weeks in five adult cows, respectively. In co...
Thompson DL, McNeill DR, Wiest JJ, St George RL, Jones LS, Garza F.Sequential samples of blood were drawn via jugular catheters every 15 min for 24 h from four mares in each of five reproductive states: intact anestrous mares in winter, intact diestrous mares in summer, intact estrous mares in summer, ovariectomized mares in winter and ovariectomized mares in summer. Estrous mares were sampled on d 4 or 5 of estrus and diestrous mares on d 10 or 11 of diestrus. Each sample of plasma was assessed for concentrations of luteinizing hormone (LH) and follicle stimulating hormone (FSH) in two independent radioimmunoassays. A computer program was developed that dete...
Savage NC, Liptrap RM.Fenprostalene (250 micrograms) or saline was given at 60 h after the onset of oestrus in alternate oestrous periods to 8 mares for 4 cycles. Onset of oestrus and stage of cycle were determined by daily teasing, palpation and ultrasonography until time of treatment when follicular development was monitored at 12-h intervals to confirm ovulation. Serum progesterone concentrations were monitored daily. The interval from treatment to ovulation was significantly decreased (41.25 vs 73.50 h; P = 0.001) as was the duration of oestrus (5.63 vs 6.88 days; P = 0.005). There was no significant difference...
Thompson DL, Johnson L.Prolactin concentrations in stallion serum were measured by radioimmunoassay based on antiserum generated against equine prolactin and radioiodinated canine prolactin. Prolactin concentrations in serum collected from 152 stallions at a slaughterhouse were higher (P less than .01) in summer than in winter (5.7 +/- .15 vs 2.0 +/- .17 ng/ml). Moreover, there was an effect of age (P less than .02) in the analysis of variance; there was no interaction between age and season. In general, prolactin concentrations increased with age up to 3 to 5 years. Samples of serum collected from five control and ...
Amann RP, Cristanelli MJ, Squires EL.Motility and fertility of frozen-thawed semen differs greatly amongst stallions. Differences in seminal plasma might be one cause of this variation. For 8 ejaculates from each of 17 stallions, seminal plasma was saved at -20 degrees C and spermatozoa were cryopreserved. Based on post-thaw sperm motility, seminal plasma samples from 7 stallions (2 good, 3 variable, 2 poor sperm motility) were selected for measurement of electrolytes, protein content and analysis by sodium dodecylsulphate gel electrophoresis (10% gel, Coomassie blue stain). Variation in seminal plasma was significant (P less tha...
Junnila M, Korkeala H, Rahko T, Salmi A.The kidney cortex of 32 Finnish horses was analysed chemically for cadmium (Cd) and selenium (Se) content and by light microscopy for histopathological changes of the tissues. Cd concentrations in kidney cortex ranged from 6.9 to 91.6 mg/kg wet weight with an average of 31.9 mg/kg. Se concentrations ranged from 0.5 to 1.5 mg/kg with an average of 1.0 mg/kg. The age of the horses varied from 1.5 to 32 years; mean age was 16 years. Cd levels in kidney cortex seemed to increase linearly up to an age of about 16 years. In old (over 16 years) horses no such correlation could be found. Se concentrat...
Arighi M, Singh A, Bosu WT, Horney FD.Abdominal, inguinal and scrotal testes of horses were examined grossly and by light microscopy. An average of 1.5, 2.3 and 4.6 layers of spermatogenic cells, and mean seminiferous tubule diameters of approximately 66.2, 83.6 and 146.6 micron in the abdominal, inguinal and scrotal testes, respectively, were recorded. The interstitial spaces and the number of interstitial cells (of Leydig) seemed to be increased while spermatogenesis appeared to be arrested in the retained testes. Early spermatocytes were the most mature stages of the spermatogenic cells in the retained testes. An extensive vacu...
Fay JE, Douglas RH.Individual antral follicles from 11 horse mares were studied at three stages of the oestrous cycle to determine the characteristics of the presumptive ovulatory follicle. Mares were ovariectomized (ovex) during the late luteal phase on Day 14 after ovulation (Group 1) and on the 1st (Group 2) or 4th (Group 3) day of oestrus. Every follicle greater than 5 mm in diameter was dissected from each ovary; follicles greater than or equal to 15 mm in diameter were analysed separately while others were pooled by size for subsequent analyses. The presumptive ovulatory follicle possessed the following ch...
Evans JW, Stanfield J, Hoffman LS, Slaussen C.Testes were obtained from 70 colts and stallions and were pooled according to age (4 months to 23 years) to determine the relationship of age to LH/hCG receptor kinetics. The receptor concentration (Rt) increased from 0.069 x 10(-11) M/mg crude membrane fraction (CMF) for the 4-14-month pools to 0.464 x 10(-11) M for the 2-3-year-old pools. A 10-fold increase in testicular size also occurred, and so the total number of receptors per testis was significantly increased. A further increase to 1.237 x 10(-11) M/mg CMF was observed for stallions older than 5 years. No differences in binding affinit...
Asbury AC, Hansen PJ.Fourteen mares, 7 susceptible and 7 resistant to bacterial endometritis, were used to provide circulating and uterine-derived neutrophils. Uterine neutrophils were recruited by inoculating cell-free filtrates of Streptococcus zooepidemicus, or control vehicle. Mares were assigned to schedules for collection of neutrophils at oestrus or dioestrus. Phagocytic activity of circulating and uterine cells was evaluated by an assay for chemiluminescence after addition of opsonized streptococci. Chemiluminescence generated by circulating neutrophils was greater (P less than 0.05) for susceptible mares ...
Antczak DF, Oriol JG, Donaldson WL, Poleman C, Stenzler L, Volsen SG, Allen WR.Monoclonal antibodies raised against horse placenta were tested using an indirect immunoperoxidase-labelling technique for reactivity with a panel of tissues from adult horses and conceptuses of various gestational ages. The pattern of reactivity of 4 of the antibodies (F67.1, F71.3, F71.7, F71.14) on trophoblastic tissues described unique antigenic phenotypes for the non-invasive trophoblast of the allantochorion, the invasive trophoblast of the chorionic girdle, and the mature endometrial cup cells, which are derived from the chorionic girdle. Two of the monoclonal antibodies (F67.1 and F71....
Magistrini M, Chanteloube P, Palmer E.In an attempt to define optimal season and ejaculation frequency for frozen semen, semen was collected from 6 stallions (3 horses and 3 ponies) 3 times per week or every day, alternating every week, for 1 year. The semen was evaluated and frozen. All the samples were thawed at the end of the experiment. At collection, fresh semen evaluations showed that winter (as opposed to spring and summer) was associated with low sexual behaviour, small volumes of spermatozoa and gel, high sperm concentration and lower motility. The high ejaculation frequency yielded a decreased volume, concentration of sp...
Strickland K, Smith F, Woods M, Mason J.Four horses were stabled and fed a diet of hay ad libitum, and 2 kg oats per animal per day, for a month. The basic diet was then supplemented with molybdenum, at a rate of 20 mg/kg dry matter for 4.5 months. For one month of this period the diet was supplemented also with sulphur at a rate of 1.2 g/kg dry matter. Analyses of jugular blood samples, obtained at intervals varying between two and 20 days, showed no evidence of a decline in total plasma copper or of an increased proportion of trichloroacetic acid (TCA) insoluble copper in plasma over this period. In separate studies, two other hor...
Numazawa M, Osawa Y.The metabolic pathway leading to equilin and equilenin biosynthesis in the pregnant mare is different from that of estrone and estradiol and it is apparently cholesterol-independent. The precise precursors and intermediates and the stereomechanism of equine placental aromatization have not been established. [1,2-3H, 4-14C]3-Hydroxy-3,5,7-androstatrien-17-one was synthesized as a potential substrate and the 3H-distribution was analyzed by biochemical and chemical derivatization methods. The substrate was converted to equilin, equilenin and Heard's ketone by horse placental microsomes with a sp....
Koterba AM, Kosch PC.Breathing pattern, respiratory muscle activation pattern, lung volumes and volume-pressure characteristics of the respiratory system of normal, term, neonatal foals on Days 2 and 7 of age were determined to test the hypothesis that the foal actively maintains end-expiratory lung volume (EEV) greater than the relaxation volume of the respiratory system (Vrx) because of a highly compliant chest wall. Breathing pattern was measured in the awake, unsedated foal during quiet breathing in lateral and standing positions. The typical neonatal foal breathing pattern was characterized by a monophasic in...
Sampaio BFB, Nogueira BG, Souza MIL, Silva EVDCE, Zúccari CESN.The aim of this experiment was to evaluate the effects of adding ascorbic acid 2-glucoside (AA2G), a water-soluble antioxidant and stable derivative of ascorbate, to the semen extender and compare it to the addition of vitamin C (Vit. C) and the fat-soluble antioxidant α-tocopherol (α-Toh), both individually and in combination, on the seminal variables of equine sperm submitted to cooling for 72 h. We used two ejaculates from 10 stallions and evaluated them for motility, membrane integrity, chromatin fragmentation, mitochondrial activity and lipid peroxidation. In the analysis of lipid pero...
Johnson AL, Becker SE, Roma ML.Standard bred mares that were cycling normally were treated beginning on Days 9 or 10 of the oestrous cycle with repeated pulses of GnRH (20 micrograms/h) and/or a single injection of prostaglandin (PG)F-2 alpha (alfaprostol, 3 mg), and were subsequently bled and palpated daily until the next ovulation. GnRH treatment increased serum concentrations of LH and progesterone at 4 days after the start of treatment compared to controls. The combination of PGF-2 alpha + GnRH treatment resulted in an immediate decline in serum progesterone values, and subsequently decreased the interval to next ovulat...
Leach D, Oliphant L.Incidental to studies of keratinization of the equine hoof wall, annular gap junctions were found in the stratum spinosum of the intertubular horn of the stratum medium. Adjacent cells of the stratum spinosum showed extensive gap junctions, and often local invaginations of one cell into another were bound by gap junctions. It is proposed that these invaginations become detached from the cell surface to form the annular gap junctions. Formation of annular gap junctions may be a means of disposing of plasma membrane in response to changes in cell volume or shape occurring in keratinization. Inte...
Hurwitz A, Finci-Yeheskel Z, Dushnik M, Milwidsky A, Shimonovitz S, Yagel S, Adashi EY, Mayer M.This study examines the effects of interleukin-1 (IL-1) on plasminogen activator (PA) activity and prostaglandin (PG) E production in pregnant mare serum gonadotropin (PMSG)-primed granulosa cells and the potential involvement of PGE in the regulation of ovarian plasminogen activation. Methods: Granulosa cells were obtained from PMSG-primed rat (27-day-old) ovaries and cultured in serum-free conditions for 48 hours in the absence or presence of IL-1 beta (10 ng/mL) with and without transforming growth factor-beta 1 (10 ng/mL). Cellular PA activity was measured through the conversion of plasmin...
Zicker SC, Vivrette S, Rogers QR.Concentrations of 16 of 24 amino acids in plasma of foetuses were significantly higher, while four of 24 were lower, than their concentration in maternal plasma. The higher foetal concentrations of amino acids in plasma are similar to other species, with some exceptions, and suggest that equine placenta actively transports and concentrates amino acids into the umbilical circulation. Concentrations of nine of 24 amino acids were significantly lower in plasma from the umbilical artery compared to plasma from the umbilical vein, while no significant differences were present between maternal arter...
Yamamoto Y.NMR signals for HisB5 N(delta)H and HisEF5 N(epsilon)H protons of sperm whale and horse apomyoglobins were assigned and compared with the corresponding signals of the holoproteins in terms of pH and temperature dependence behaviors of their shifts and line widths in order to gain insight into structural difference between the apoproteins and the holoproteins. Since these protons are involved in internal hydrogen bonds at the interfaces between the B helix and the GH corner and between the EF corner and the H helix, local structures of the interfaces in these proteins have been inferred from th...
Habel RE, Budras KD.Analyses of the fibers in the prepubic tendon of the horse and ruminants have shown that it is composed of the crossed and uncrossed tendons of origin of the pectineus muscles, the pelvic tendons of the rectus and obliquus abdominis muscles, and the tendons of origin of the cranial parts of the gracilis muscles. Pelvic attachments of the linea alba and the yellow abdominal tunic are incorporated in it. It is not a transverse ligament, and it is not homologous to the human superior (cranial) pubic ligament. The dog differs in 4 respects: (1) the pectineus tendons do not cross, but each originat...
McCandless EE, Rai SK, Mwangi D, Sly L, Franz LC.Hydrocortisone is widely accepted as an anti-inflammatory agent and there are many products available containing hydrocortisone as an active ingredient. Surprisingly, there is little data available specifically on the immunological effects of hydrocortisone in large animals. Glucocorticoids are well-characterized for their ability to repress inflammation via a wide variety of mechanisms including suppression of cytokine production. In this study the effects of hydrocortisone on IFN-γ production by equine, bovine, and ovine PBMCs were assessed using flow cytometric or ELISpot analysis. Hydroco...
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...
Braid F, Williams SB, Weller R.Recognition of anatomical landmarks in live animals (and humans) is key for clinical practice, but students often find it difficult to translate knowledge from dissection-based anatomy onto the live animal and struggle to acquire this vital skill. The purpose of this study was to create and evaluate the use of an equine anatomy rug ("Anato-Rug") depicting topographical anatomy and key areas of lung, heart, and gastrointestinal auscultation, which could be used together with a live horse to aid learning of "live animal" anatomy. Over the course of 2 weeks, 38 third year veterinary students were...
Lancaster LS, Bowker RM, Mauer WA.To quantify the density of primary epidermal laminae (PELs) around the solar circumference and evaluate the relationship between regional PEL density and hoof capsule morphology in horses. Methods: Forefeet from nine 3-year-old Quarter Horse cadavers. Methods: Data pertaining to gross features of hoof morphology and PEL variables, including number, density, and distribution patterns around the perimeter of the hoof wall and number of bar PELs, were collected. Tissues of the laminar junction were examined histologically. Results: No significant differences were found between left and right fore...
Vörös K, Holmes JR, Gibbs C.This study was designed to evaluate the accuracy of two-dimensional echocardiography (2DE) in determining the left ventricular volume (LVV) of the horse in vitro. After examining the shape of the left ventricular silicon rubber casts of four equine hearts, two modified Simpson's rule methods (Model A and Model B) as combinations of conical shapes and one biplane area-length method as a single cone (Model C) were chosen for volume calculations. One long axis and three short axis planes were used for linear and area 2DE measurements, respectively. The ventricular length (L) was calculated from t...
Mykkänen AK, Pösö AR, McGowan CM, McKane SA.In exercising horses, up to 50% of blood lactate is taken up into red blood cells (RBCs). Lactate transporter proteins MCT1, MCT2 and CD147 (an ancillary protein for MCT1) are expressed in the equine RBC membrane. In Standardbreds (SB), lactate transport activity is bimodally distributed and correlates with the amount of MCT1 and CD147. About 75% of SB studied have high lactate transport activity in RBCs. In other breeds, the distribution of lactate transport activity is unknown. Objective: To study whether similar bimodal distribution of MCT1 and CD147 is present also in the racing Finnhorse ...
Rossetto L, Farcey MF, Bilbao MG, Bartolomé JA, Gallelli MF, Miragaya MH.The stress associated with training may reduce reproductive efficiency in Criollo stallions. The objective of this study was to compare semen quality and hormone concentrations in Criollo stallions under training or under regular field conditions. Criollo breed stallions (n = 18) were evaluated during the spring. The exercise group (n = 9) performed 1 hour of exercise per day and participated in competitions during the experimental period. The control group (n = 9) neither performed exercise nor participated in competitions. Serum and semen samples were obtained every 15 days (two separat...
Menzer C, Schams D.A double-antibody radioimmunoassay for PMSG, especially for meauring PMSG in cattle blood after exogenous application, has been developed. A rabbit antiserum against PMSG and pure PMSG for radioiodination were used. There was a strong cross-reaction against equine LH and FSH, but the slight cross-reaction against bovine LH and FSH could be eliminated by adding bovine LH to each tube during the assay. Unspecific, interfering influences of equine or cow serum could be eliminated by adding a constant amount of PMSG-free serum to each tube. PMSG added to 200 microliter of serum could be recovered ...
Freeman DE, Ferrante PL, Palmer JE.A Latin square design was used to compare the effects of laxatives and a corresponding volume of water on gastrointestinal tract function in 4 healthy horses. Horses were intragastrically infused with each of the following: dioctyl sodium sulfosuccinate (DSS; 50 mg/kg of body weight); magnesium sulfate (0.5 g/kg--low dosage); magnesium sulfate (1.0 g/kg--high dosage); and an equal volume of water (6 L) given as a control infusion. From 5 to 33 hours after the high dosage of magnesium sulfate, feces were slightly softer than usual in all horses. In 1 horse, DSS caused mild colic, hyperpnea, and...
Vonaparti A, Lyris E, Panderi I, Koupparis M, Georgakopoulos C.Levodopa and dopamine have been abused as performance-altering substances in horse racing. Urinary 3-methoxytyramine is used as an indicator of dopaminergic manipulation resulting from dopamine or levodopa administration and is prohibited with a urinary threshold of 4 microg mL(-1) (free and conjugated). A simple liquid chromatographic (LC)/mass spectrometric (MS) (LCMS) method was developed and validated for the quantification and identification of 3-methoxytyramine in equine urine. Sample preparation involved enzymatic hydrolysis and protein precipitation. Hydrophilic interaction liquid chro...
Waheed MM, Meligy A, Alhaider AK, Ghoneim IM.Seminal plasma contains several microelements like Zn, Fe, Se, and Cu that affect sperm motility and male fertility. Biochemical evaluation of seminal plasma trace elements is important for assessing fertility and diagnosing male infertility. Unassigned: The present study was designed to evaluate the effect of seminal fluid trace elements on sperm parameters and fertility in Arabian horses. Unassigned: Ninety-four ejaculates from 25 Arabian stallions (4-27 years old) were used to investigate the effect of seminal fluid trace elements on semen parameters and fertility. Data divided according to...
Suter M, Fey H.An enzyme-linked immuno sorbent assay (ELISA) for measuring horse IgE specific to ovalbumin, bencylpenicilloic acid and odinitrocarboxyphenol is described. We used a sandwich type of ELISA by which horse serum was incubated in antigen-coated tubes containing one additional polystyrene ball, followed by rabbit anti horse IgE serum. The tubes were then incubated with biotinylated goat anti rabbit globulin followed by avidin coupled to phosphatase. Endpoint titrations were compared. The ELISA is highly reproducible due to the pretreatment of the polystyrene with glutaraldehyde. The increased anti...
Chu SAA, Stokol T.The myeloperoxidase index (MPXI), on ADVIA hematology analyzers, reflects the mean neutrophil myeloperoxidase staining. It is used as a marker of inflammation in animals and people, but assay variability and storage stability are unknown. Objective: We aimed to determine MPXI precision and stability with refrigerated storage of canine and equine EDTA-anticoagulated blood and compared MPXI results between two analyzers. Methods: Inter-assay coefficients of variations (CVs) were determined from three human-based controls assayed before and after a 20- or 21-day calibration. Blood from 14-16 dogs...
Silvia PJ, Squires EL, Nett TM.Four groups of mares, representing anestrus (AN; n = 8), early transition (ET; n = 7), late transition (LT; n = 8) and estrus (EST; n = 12) were used to examine release of luteinizing hormone (LH) and follicle stimulating hormone (FSH) after a bolus injection of gonadotropin releasing hormone (GnRH) during the transition from anestrus into the breeding season. Estrous mares received GnRH on d 2 or 3 of estrus in the cycle immediately preceding slaughter. Anestrous, ET and LT mares received GnRH exactly 1 wk prior to slaughter. A single injection of GnRH (Sigma LHRH, L-0507, 2.0 micrograms/kg b...
Pietra M, Guglielmini C, Nardi S, Gandini G, Cipone M.To describe the pulsed-wave Doppler tracing of the equine lateral palmar digital artery and its modification in relation to standardized changes in posture. Methods: 17 healthy Saddlebred horses. Methods: Pulsed-wave Doppler examinations of left and right lateral palmar digital arteries of the horses were performed. The baseline examination was performed on each forelimb while horses were standing squarely with the body weight equally distributed among the 4 limbs (BED position). For each forelimb, the examination was repeated during 3 standardized modifications of the horse's posture (non-wei...
Dias AJ, Maia MS, Retamal CA, López ML.The expression of alpha-1,4-glucosidase activity was fluorometrically and electrophoretically assessed in the epididymal fluid and seminal plasma of stallions. alpha-Glucosidase specific activity in the epididymis increased significantly from the proximal caput to the cauda. Stallion epididymal glucosidase maintained activity in a wide range of pH, with two distinct peaks (around pH 4.0 and 6.0, respectively). Enzyme activities at different pH, inhibition assays with sodium dodecyl sulfate (SDS) and maltotriose (MTT, selective inhibitors of alpha-glucosidases "acidic" and "neutral" isoforms, d...
Soma LR, Sams R, Duer W, Tobin T, Woodward C, McDonald J.The plasma and serum concentrations of phenylbutazone (PBZ) and oxyphenbutazone were measured in 158 Thoroughbred horses after various doses of PBZ wer given. All horses were competing or training at racetracks in various parts of the country. All horses used in the study had not been given PBZ 24 hours before they were placed on a specific dosage schedule. Samples were collected 24 hours after the last PBZ administration. Four grams of PBZ were given daily by stomach tube, paste, or tablet for 3 days. On day 4, 24 hours before sample collection, an IV dose of 2 g of PBZ was given, regardless ...
Martin KL, Hoffman RM, Kronfeld DS, Ley WB, Warnick LD.Changes in serum concentrations of Ca and parathyroid hormone (PTH) may develop in periparturient mares, may be influenced by dietary Ca, and may be associated with changes in Ca concentration of mammary secretion. Milk and blood samples were taken from eight mares on Farm A and eight on Farm B for 10 d before parturition and from four mares on each farm for 5 d postpartum. Milk Ca was measured by two commercial tests. Serum samples were analyzed for PTH and total Ca in 16 mares and for ionized Ca in six (Farm A). Parturition was induced in eight mares on Farm A and four on Farm B; no signific...
Amselgruber WM, Sinowatz F, Erhard M.The present study deals with the immunohistochemical localization of S-100 protein in the testes of seven mammalian species including rat, cat, dog, pig, sheep, cattle and horse. Significant differences are demonstrated in the cellular distribution and intensity of immunoreaction for the protein. In bull, ram, boar and cat testes S-100 protein was localized in the cytoplasm and nuclei of Sertoli cells. A particularly intense staining was seen in the modified Sertoli cells of the terminal tubular segment. With the exception of the cat and horse S-100 protein immunoreactivity was additionally fo...
Elsner R.Examples of exercise performance and metabolic scope in non-human mammalian species are considered from the point of view of problems and questions which may provide insights into evolutionary processes influencing adaptations to muscular activity. Consideration of both aerobic and anaerobic performance is required. Some recent approaches, notably that concerned with the concept of symmorphosis, the integration of design for the accommodation of variations in activity, show promise of new ways for comparative investigations of the adjustments to exercise.
Zicarelli F, Tudisco R, Lotito D, Musco N, Iommelli P, Ferrara M, Calabrò S, Infascelli F, Lombardi P.Determination of digestibility represents the first step for the evaluation of the net energy content of feed for livestock animals. The aim of this study was to evaluate the in vivo digestibility and in vitro degradability of five diets characterized by different forage/concentrate ratios (F:C) in horses. The in vitro degradability was determined by the Gas Production Technique (GPT), using as an inoculum source the feces of the same subjects used for the in vivo test. Five diets consisting of poliphyte hay, straw and grains of barley and oats with a different F:C ratio [90/10 (Diet 1); 78/22...
Lindåse S, Johansson H, Månsby M, Bröjer J.The hyperglycaemic clamp has been used for measurement of insulin sensitivity (IS) but not for measurement of β-cell response in the horse. However, the repeatability of this test has not been reported for horses. Objective: To determine the repeatability and reliability of measures for IS and β-cell response to glucose using the hyperglycaemic clamp in horses. Methods: Repeated measures, longitudinal study. Methods: Six healthy Standardbred mares underwent a 120-min hyperglycaemic clamp on two occasions with a 10-day washout period. Indices of repeatability and reliability were calculated f...
Hill AC, Polak-Vogelzang AA, Angulo AF.Acholeplasma strains were isolated from the nasopharynx of a horse (strain PN525T [T = type strain]) and the feces of a rabbit (strain B1). One clone of strain PN525T and one clone of strain B1 were examined in detail. These clones were indistinguishable from each other and were serologically distinct from the previously described Acholeplasma and Mycoplasma spp. The strains had the following properties: guanine-plus-cytosine content of 31 mol%; sterol was not required for growth, which occurred under both aerobic and anaerobic conditions; glucose was metabolized; and arginine was hydrolyzed. ...
