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.
Malisauskas M, Zamotin V, Jass J, Noppe W, Dobson CM, Morozova-Roche LA.The calcium-binding equine lysozyme has been found to undergo conversion into amyloid fibrils during incubation in solution at acidic pH. At pH 4.5 and 57 degrees C, where equine lysozyme forms a partially unfolded molten globule state, the protein forms protofilaments with a width of ca. 2 nm. In the absence of Ca(2+) the protofilaments are present as annular structures with a diameter of 40-50 nm. In the presence of 10 mM CaCl(2) the protofilaments of equine lysozyme are straight or curved; they can assemble into thicker threads, but they do not appear to undergo circularisation. At pH 2.0, ...
Soboll G, Horohov DW, Aldridge BM, Olsen CW, McGregor MW, Drape RJ, Macklin MD, Swain WF, Lunn DP.We have previously demonstrated that hemagglutinin (HA) gene vaccination and influenza virus infection generate protective antibody responses in equids. However, these antibody responses differ substantially in that particle mediated DNA vaccination does not induce an immunoglobulin A (IgA) response. A study was performed to investigate the regional immunoregulatory mechanisms associated with these different immune responses. Ponies were either vaccinated with equine HA DNA vaccines at skin and mucosal sites, infected with influenza virus or left untreated and influenza-specific antibody respo...
Stecco R, Paccamonti D, Gutjahr S, Pinto CR, Eilts B.Oxytocin is released in response to teasing during both estrus and diestrus in mares, and at least during estrus, teasing results in an increase in electromyographic activity in the uterus. Exogenous oxytocin causes an increase in intrauterine pressure and prior studies have shown that this response is correlated to the day of the estrous cycle. To determine if teasing causes an increase in intrauterine pressure and if this response varies by day of the cycle, intrauterine pressure was measured while mares were teased with a stallion 2 days before ovulation, on the day ovulation was detected a...
Butudom P, Axiak SM, Nielsen BD, Eberhart SW, Schott HC.Body mass (BM), water intake (WI), and plasma osmolality (P(osm)) and electrolyte concentrations were measured in six 2-year-old Arabian horses provided either 4 l, 8 l, or an unlimited amount of water (UW) for drinking during the initial 5 min of recovery from 45-km of treadmill exercise. After weighing, horses were placed in a stall and further WI between 20 and 60 min of recovery was measured. During exercise, horses lost 3.3+/-0.3%, 3.2+/-0.1%, and 3.3+/-0.2% (P>.05) of BM and P(osm) increased by 7.2+/-0.5, 7.9+/-0.8, and 7.7+/-0.5 mOsm/kg (P>.05) for 4 l, 8 l, and UW, respectively. ...
Bollwein H, Mayer R, Stolla R.Transrectal color Doppler sonography was used for the noninvasive investigation of uterine blood flow in five mares. Both the left and right uterine arteries were scanned to obtain blood flow velocity waveforms during two consecutive estrous cycles and two early pregnancies in each mare. Blood flow was expressed as the time-averaged maximum velocity (TAMV) and the resistance index (RI). In all pregnancies the embryonic vesicle could be detected for the first time on Day 11 (day of ovulation: Day 0). No differences in mean TAMV and RI values of both uterine arteries were observed in comparison ...
Ochi S, Oda M, Nagahama M, Sakurai J.Clostridium perfringens alpha-toxin is able to lyse various erythrocytes. Exposure of horse erythrocytes to alpha-toxin simultaneously induced hot-cold hemolysis and stimulated production of diacylglycerol and phosphorylcholine. When A23187-treated erythrocytes were treated with the toxin, these events were dependent on the concentration of extracellular Ca2+ . Incubation with the toxin of BAPTA-AM-treated horse erythrocytes caused no hemolysis or production of phosphorylcholine, but that of the BAPTA-treated erythrocytes did. When Quin 2-AM-treated erythrocytes were incubated with the toxin i...
Plummer CE, Ramsey DT, Hauptman JG.To determine corneal thickness, intraocular pressure (IOP), and horizontal and vertical corneal diameter (HCD and VCD) and to obtain axial measurements of the anterior chamber depth (ACD), crystalline lens thickness (CLT), vitreous chamber depth (VtCD), and axial globe length (AGL) in eyes of Miniature Horses. Methods: 41 healthy Miniature Horses. Methods: Ocular component measurements were obtained via ultrasonic pachymetry, applanation tonometry, ultrasound, and by use of a Jameson caliper. Results: Mean IOP and corneal thickness for all eyes were 26.0 mm Hg and 785.6 microm, respectively. T...
Mallem MY, Gogny M, Gautier F, Bucas V, Desfontis JC.To investigate the functional expression of beta3-adrenoceptors (beta3-ARs) in equine digital veins (EDVs) and to examine whether beta3-AR relaxation was altered in EDVs incubated with endotoxin. Methods: Forelimbs obtained from 30 horses. Methods: Forelimbs were obtained from horses in an abattoir. Equine digital veins were carefully removed from distal portions of the forelimbs. Rings of dissected EDVs were mounted in 5-mL organ baths to record isometric tension in the presence of various beta3-AR agonists (SR 58611A, ZD 2079, and ZM 215001). Results: In intact EDVs, isoprenaline, SR 58611A,...
Spadavecchia C, Arendt-Nielsen L, Andersen OK, Spadavecchia L, Doherr M, Schatzmann U.To compare nociceptive withdrawal reflexes (NWRs) evoked from the distal aspect of the left forelimb and hind limb in conscious standing horses and to investigate NWR recruitment for graded electrical stimulation intensities. Methods: 20 adult horses. Methods: Surface electromyographic (EMG) activity evoked by transcutaneous electrical stimulation of the digital palmar (or plantar) nerve was recorded from the common digital extensor and cranial tibial muscles. Stimuli consisted of 25-millisecond train-of-5 constant current pulses. Current intensity was gradually increased until NWR threshold i...
Byron CR, Orth MW, Venta PJ, Lloyd JW, Caron JP.To characterize potential mechanisms of action of glucosamine inhibition of matrix metalloproteinase (MMP) expression and activity in lipopolysaccharide (LPS)-stimulated equine chondrocytes. Methods: Chondrocytes cultured from samples of metacarpophalangeal articular cartilage collected from cadaveric limbs of horses. Methods: The effect of glucosamine on MMP activity in conditioned medium from LPS-stimulated cartilage explants was determined by a colorimetric assay with azocoll substrate. Treatments consisted of negative and positive controls, glucose (50 mM), and glucosamine (50, 25, 6.25, 3...
Baumber J, Ball BA, Linfor JJ, Meyers SA.The objective of this study was to examine the effect of reactive oxygen species (ROS) and cryopreservation on DNA fragmentation of equine spermatozoa. In experiment 1, equine spermatozoa were incubated (1 hour, 38 degrees C) according to the following treatments: 1) sperm alone; 2) sperm + xanthine (X, 0.3 mM)-xanthine oxidase (XO, 0.025 U/mL); 3) sperm + X (0.6 mM)-XO (0.05 U/mL); and 4) sperm + X (1 mM)-XO (0.1 U/mL). In experiment 2, spermatozoa were incubated (1 hour, 38 degrees C) with X (1 mM)-XO (0.1 U/mL) and either catalase (200 U/mL), superoxide dismutase (SOD, 200 U/mL), or reduced...
Miller MA, Kottler SJ, Ramos-Vara JA, Johnson PJ, Ganjam VK, Evans TJ.Response to 3-methylindole (3MI) varies among species. Mice recover from 3MI-induced bronchiolar epithelial injury but sustain persistent olfactory mucosal injury with scarring and epithelial metaplasia. In contrast, 3MI induces obliterative bronchiolitis in horses and ponies, but olfactory mucosal injury has not been reported. To evaluate the effect of 3MI on equine olfactory mucosa, ponies were dosed orally with 100 mg 3MI/kg (n = 9) or corn oil vehicle (n = 6). All ponies treated with 3MI developed obliterative bronchiolitis with mild olfactory injury. By 3 days after 3MI dosing, olfactory ...
Schwartz S, Elnitski L, Li M, Weirauch M, Riemer C, Smit A, Green ED, Hardison RC, Miller W.Analysis of multiple sequence alignments can generate important, testable hypotheses about the phylogenetic history and cellular function of genomic sequences. We describe the MultiPipMaker server, which aligns multiple, long genomic DNA sequences quickly and with good sensitivity (available at http://bio.cse.psu.edu/ since May 2001). Alignments are computed between a contiguous reference sequence and one or more secondary sequences, which can be finished or draft sequence. The outputs include a stacked set of percent identity plots, called a MultiPip, comparing the reference sequence with sub...
Ha TY, Ahn MJ, Lee YD, Yang JH, Kim HS, Shin TK.Lectins are glycoproteins of plant and animal origin that have the ability to bind specific carbohydrate residues of cell glycoconjugates, particularly in terminal positions. In this study, the binding of lectins, Dolichos biflorus agglutinin (DBA), soybean agglutinin (SBA), Bandeiraea simplicifolia BS-1 (isolectin B4), Triticum vulgaris (WGA), Arachis hypogaea (PNA), and Ulex europaeus (UEA-I), was studied in the reproductive systems of male thoroughbred horses.DBA was detected in the stereocilia of the caput and corpus epididymis, and in the vas deferens. It was weakly detected in connective...
Ginther OJ, Beg MA, Donadeu FX, Bergfelt DR.Diameter deviation is a distinctive change in growth rates among the follicles of a wave, heralding the formation of a dominant follicle and subordinate follicles. When the follicles are about 5mm in cattle and 13 mm in horses, the wave-stimulating FSH surge reaches peak concentrations. Follicle and FSH manipulation studies in both species have shown that the declining portion of the surge before the beginning of deviation is a function of multiple growing follicles that require the decreasing FSH. During this time, all follicles of the wave have the potential for future dominance. Deviation b...
Lee JY, Kang TY, Lee YD, Shin TK.The binding specificities of various lectins, such as the Dolichos biflorus agglutinin (DBA), soybean agglutinin (SBA), and the Bandeiraea simplicifolia BS-1 (Isolectin B4), Triticum vulgaris (WGA), Arachis hypogaea (PNA), and Ulex europaeus (UEA-I) lectins, were studied in the vomeronasal organ of the horse. The microvilli of the vomeronasal sensory epithelium were positive for DBA, SBA, Isolectin B4, WGA, PNA, and UEA-I. The receptor cells showed intense reactivity for DBA and WGA. Lectins were not detected in the supporting cells or basal cells. The Jacobson's glands were positive for WGA a...
Hicks BA, Etter SJ, Carnahan KG, Joyce MM, Assiri AA, Carling SJ, Kodali K, Johnson GA, Hansen TR, Mirando MA, Woods GL, Vanderwall DK, Ott TL.Pregnancy and interferon-tau (IFN tau) upregulate uterine Mx gene expression in ewes; however, the only known role for Mx is in the immune response to viral infection. We hypothesize that Mx functions as a conceptus-induced component of the anti-luteolytic mechanism and/or regulator of endometrial secretion or uterine remodeling during early pregnancy. This study was conducted to determine the effects of early pregnancy on uterine Mx expression in domestic farm species with varied mechanisms of pregnancy recognition. Endometrium from cows, gilts, and mares was collected during the first 20 d o...
Erichsen C, Eksell P, Widström C, Roethlisberger Holm K, Johnston C, Lord P.Scintigraphic evaluation of the spinous processes of the equine spine has been done by subjective evaluation of radiotracer uptake in clinically abnormal horses. To determine the range of variation in asymptomatic riding horses, 33 normal horses were examined. Two 60 degrees oblique views of the thoracic and lumbar spine were evaluated subjectively, and a semi quantitative method based on standardized regions of interest in each spinous process in T10-L3 was also applied. A ratio between each spinous process and a reference area (Rib 15 or 16) was calculated. The effects of two different color...
Sato T, Itou T, Sakai T.The complete coding region sequence of equine muscle-type phosphofructokinase (ePFKM) was obtained from skeletal muscle of a thoroughbred horse. The deduced amino acid sequence of ePFKM showed 97%, 96%, 96%, 96% and 95% identity to canine, human, mouse, rabbit and rat PFKM, respectively. The amino and carboxyl terminal halves of ePFKM presented a structure of tandem repeat, as other mammalian PFKMs. As the amino acid residues constituting various ligand-binding sites were also conserved, it is thought that ePFKM has enzymatic activity similar to PFKM in other mammals.
Arai T, Inoue A, Uematsu Y, Sako T, Kimura N.The activities of the enzymes involved in the malate-aspartate shuttle and lactate dehydrogenase (LDH) and the pattern of the isoenzymes of LDH were determined in plasma and peripheral leukocytes of lactating Holstein cows and thoroughbred riding horses as representative herbivorous animals. In the horse plasma, LDH activities were significantly lower and AST activities were significantly higher than those in the cow plasma. The specific activities of cytosolic malate dehydrogenase (MDH), LDH and AST in the horse leukocytes were higher than those in the cows. The cytosolic ratio of MDH/LDH act...
Wille KH, Schnorr B.Arterioles, precapillary sphincters, capillary endothelium, and pericytes probably regulate the blood flow in the intestinal microvascular bed similar to other regions of the body because of their equipment with contractile filaments. Only throttle veins with their arrangement of pools and their characteristics probably exert influence on the hemodynamic qualities of the blood flow in the intestinal mucosa.
Skedros JG, Dayton MR, Sybrowsky CL, Bloebaum RD, Bachus KN.It has been hypothesized that a major objective of morphological adaptation in limb-bone diaphyses is the achievement of uniform regional safety factors between discrete cortical locations (e.g. between cranial and caudal cortices at mid-diaphysis). This hypothesis has been tested, and appears to be supported in the diaphyses of ovine and equine radii. The present study more rigorously examined this question using the equine third metacarpal (MC3), which has had functionally generated intracortical strains estimated by a sophisticated finite element model. Mechanical properties of multiple mid...
Kuhnert P, Berthoud H, Christensen H, Bisgaard M, Frey J.Equine Actinobacillus species were analysed phylogenetically by 16S rRNA gene (rrs) sequencing focusing on the species Actinobacillus equuli, which has recently been subdivided into the non-haemolytic A. equuli subsp. equuli and the haemolytic A. equuli subsp. haemolyticus. In parallel we determined the profile for RTX toxin genes of the sample of strains by PCR testing for the presence of the A. equuli haemolysin gene aqx, and the toxin genes apxI, apxII, apxIII and apxIV, which are known in porcine pathogens such as Actinobacillus pleuropneumoniae and Actinobacillus suis. The rrs-based phylo...
Grulke S, Deby-Dupont G, Gangl M, Franck T, Deby C, Serteyn D.Shock is accompanied by generalised splanchnic hypoperfusion, and splanchnic organs like the pancreas can be damaged, as shown in animal experimental models and in humans, by the presence of high plasma concentrations of trypsin and other pancreatic enzymes. In order to design a radioimmunoassay technique (RIA) for the measurement of equine trypsin-like immunoreactivity (TLI) in biological fluids, trypsin was purified (with purity > or = 96%) from the equine pancreas by extraction in an acid medium, ammonium sulfate precipitations, gel filtration chromatography and, after activation of tryp...
Kim DY, Taylor HW, Moore RM, Paulsen DB, Cho DY.Osteoarthritis (OA) is the most common joint disease in horses. Chondrocyte apoptosis has been implicated as a major pathological OA change in humans and experimental animals but no studies have been performed on equine OA. Articular cartilage was collected from three normal and five OA horses. Histopathological changes were scored by a modified Mankin grading system. A terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) assay was performed to identify chondrocyte apoptosis. Nitric oxide (NO) production from chondrocytes was indirectly evaluated by immunohistochemistr...
Hada T, Onaka T, Takahashi T, Hiraga A, Yagi K.This study investigated the effects of novelty stress on neuroendocrine activities and running performance in Thoroughbred horses. First, to examine the neuroendocrine responses to novelty stress, we exposed horses to two types of novel environmental stimuli (audiovisual or novel field stimuli). After the stimuli, plasma concentrations of vasopressin, catecholamines and adrenocorticotropin (ACTH), as well as heart rates, were significantly increased in each experiment. Second, we investigated neuroendocrine activities during incremental exercise. Plasma concentrations of vasopressin, catechola...
Nollet H, Van Ham L, Deprez P, Vanderstraeten G.Transcranial magnetic stimulation is rapidly developing as a powerful, non-invasive tool for studying the descending motor tracts in humans. The applications of the test in animals are for the moment restricted to small animals. However, this non-invasive, sensitive and painless technique appears promising as a test of motor tract function in horses where the neurological examination is mainly restricted to clinical evaluation and some ancillary tests, such as radiography, cerebrospinal fluid analysis and electromyography. In this review, we want to discuss the history, basic principles, techn...
Père MC.Several general features of nutrient uptake and utilisation by foetuses are similar among mammalian species. Nevertheless, there are also differences linked mainly to differences in placental permeability. Glucose and lactate are the main energetic substrates of the foetus. In normal conditions, the oxidation of carbohydrates accounts for about 75, 60 and 50% of oxygen uptake in the foetal pig, foal and lamb, respectively, and acetate accounts for about 10% in ruminants. Acidic amino acids are synthesised by the foetus, whereas neutral and basic amino acids are transported from the placenta. A...
Carter CA, Jolly DG, Worden CE, Hendren DG, Kane CJ.Nonhealing wounds of the lower equine limb represent a challenging model. The platelet is a natural source of a myriad of growth factors and cytokines that promote wound healing. This study evaluates the potential of platelet derived factors to enhance wound healing in the lower equine limb. Platelets were isolated from horse blood and activated with thrombin, a process known to induce growth factor release. This produced a platelet gel composed of platelet-rich plasma (PRP). To test this all-natural wound healant, 2.5-cm(2) full thickness cutaneous wounds were created below the knee and hock ...
Lelláková M, Lešková L, Florián M, Mesarčová L, Skurková L, Peťková B, Takáčová D, Kottferová J.The determination of cortisol concentrations in animal hair appears to be a relatively simple and non-invasive method of assessing chronic stress. This method has advantages but it also has some drawbacks. We discovered that there are specific coat properties and individual factors in animlas that can affect corisol levels and skew the interpretation of results. We removed horsehair from 8 different areas of the body (chest, left saddle, right saddle, right thoracic fetlock, and left thoracic fetlock, the mane was also sampled at the withers, just behind the ears, and the tail strand) in 31 ho...
Bogers SH, Rogers CW, Bolwell C, Roe W, Gee E, McIlwraith CW.To compare regional proportions and spatial distributions of volumetric bone mineral density (BMDv) of the palmar aspect of the distal epiphysis of the third metacarpal bone (McIII) in limbs with or without a condylar fracture from Thoroughbred racehorses. Methods: McIIIs from cadavers of Thoroughbred racehorses with (n = 6 bones) and without (8) a condylar fracture. Methods: BMDv and spatial distributions of BMDv in peripheral quantitative CT images of the distal epiphysis of McIIIs were quantitatively assessed with spatial analysis software. Relative proportions of voxels within 9 threshold ...
Lancheros-Buitrago J, Rodriguez-Villamil P, Gregory J, Bastos H, Camacho CA, Caballeros JE, Cazales N, Barros E, José de Jesus Silva M, Pimentel A....Characterization of the uterine proteome before the entry of the conceptus to the uterus is essential to know the factors involved in the physiological events of gestation. The objective of the study was to compare proteomic profile of uterine fluid collected on day 5 post ovulation of cyclic and inseminated mares. Samples of endometrial secretion were recovered over 2 cycles during the fifth day post ovulation. The first cycle constituted the Cyclic group and in the following cycle, the same mares were inseminated and considered as the Inseminated group. All the samples were subjected to two-...
Wiseman M, Henson F, Lee DA, Bader DL.Chondrocytes within articular cartilage respond to the mechanical stresses associated with normal joint loading via a series of signalling pathways. Specific biomolecules, such as nitric oxide (NO), have been implicated in these mechanotransduction processes. It has been shown that the synthesis of NO can be inhibited by dynamic compressive strain of chondrocytes in vitro which, in turn, leads to an up-regulation of specific metabolic parameters. Objective: Chondrocytes isolated from different joint locations and seeded in agarose constructs respond in a distinct manner to the application of d...
Ząbek T, Semik-Gurgul E, Szmatoła T, Gurgul A, Fornal A, Bugno-Poniewierska M.Horses are one of the longest-living species of farm animals. Advanced age is often associated with a decrease in body condition, dysfunction of immune system, and late-onset disorders. Due to this, the search for new solutions in the prevention and treatment of pathological conditions of the advanced age of horses is desirable. That is why the identification of aging-related changes in the horse genome is interesting in this respect. In the recent years, the research on aging includes studies of age-related epigenetic effects observed on the DNA methylation level. We applied reduced represent...
Chodkowska KA, Ciecierska A, Majchrzak K, Ostaszewski P, Sadkowski T.Gamma-oryzanol (GO) is a popular supplement for performance horses, dogs, and humans. Previous studies indicated that GO supplementation decreases creatine kinase activity and lactate level after exercise and may affect oxidative stress in Thoroughbred horses. GO may change genes expression in equine satellite cells (ESC). The purpose of this study was to evaluate the effect of GO on miRNA, gene expression, oxidative stress, and cell damage and viability in differentiating ESC pretreated with hydrogen peroxide (H₂O₂). ESCs were obtained from a young horse's skeletal muscle. ESCs were pre-i...
Barton MH, Bruce EH, Moore JN, Norton N, Anders B, Morris DD.To test efficacy of murine monoclonal, rabbit polyclonal recombinant equine or human tumor necrosis factor-alpha (rETNF or rHTNF, respectively) antibodies to inhibit native equine tumor necrosis factor (TNF) activity. Methods: 8 and 18 healthy adult horses for parts 1 and 2 of the study, respectively. Methods: In part 1, supernates from endotoxin-activated peritoneal macrophages were incubated with various dilutions of each rETNF antibody and subsequently tested for TNF activity. Serum was also obtained from a horse 1 hour after infusion with 20 ng of endotoxin/kg of body weight and was incuba...
Lavoie JP, Pascoe JR, Kurpershoek CJ.The effects of 3 commonly used dosages (0.3, 0.5, and 1.1 mg/kg of body weight, IV) of xylazine on ventilatory function were evaluated in 6 Thoroughbred geldings. Altered respiratory patterns developed with all doses of xylazine, and horses had apneic periods lasting 7 to 70 seconds at the 1.1 mg/kg dosage. Respiratory rate, minute volume, and partial pressure of oxygen in arterial blood (PaO2) decreased significantly (P less than 0.001) with time after administration of xylazine, but significant differences were not detected among dosages. After an initial insignificant decrease at 1 minute a...
Gregory SJ, Brooks J, McNeilly AS, Ingleton PM, Tortonese DJ.An interaction between gonadotroph and lactotroph cells of the pituitary gland has long been recognized in several species. The current study was conducted to investigate whether an association between gonadotrophs and lactotrophs occurs in mares and whether prolactin receptors are expressed within the pituitary gland of this species. The effects of both reproductive state and season on these variables were examined in pituitary glands obtained from sexually active mares in July (breeding season), sexually active mares in November (non-breeding season) and anoestrous mares in November. Pituita...
Malark JA, Nixon AJ, Skinner KL, Mohammed H.Physical, biochemical, and cytologic properties of synovial fluid from digital flexor tendon sheaths of clinically normal horses were investigated. Tendon sheath fluid was pale yellow, clear, and did not clot. Volume of fluid within a tendon sheath varied minimally, with a mean of 2.11 ml. Total erythrocyte counts were higher than values observed in normal equine joint fluid, whereas values for total leukocyte count (770 +/- 73 cells/mm3), viscosity (6.05 +/- 0.58 cs), and protein concentration (7.87 +/- 0.03 mg/ml) were similar to those in joint fluid. Large mononuclear cells were the predomi...
Katz LM, Marr CM, Elliott J.Substance P (SP), a potent vasodilator, has been detected in equine digital sensory-motor nerves. The aim of the study was to characterise the functional responses of equine digital blood vessels to exogenous SP. Pre-constricted equine digital arteries (EDA) and veins (EDV) vasodilated in a biphasic, endothelium- and concentration-dependent manner to SP. A nitric oxide (NO) synthase inhibitor Nomega-nitro-L-arginine methyl ester hydrochloride (L-NAME; 300 microm) inhibited both phases of the relaxation response curve of EDAs to SP by >70%. In EDVs, the first relaxant phase to SP was largely...
Manohar M, Goetz TE.Blood flow to the brain, kidneys, adrenal glands, pancreas, and small intestine was studied in 8 healthy ponies while awake (control) and during 1.0, 1.5, and 2.0 minimal alveolar concentrations (MAC) of anesthesia produced, using halothane vaporized in oxygen. During the anesthesia steps, intermittent positive-pressure ventilation was used to ensure isocapnia. Organ blood flow was determined with 15-micron (diameter) radionuclide-labeled microspheres, after allowing 30 minutes of equilibration at each of the 3 preestablished end-tidal halothane concentrations. The sequence of 1.0, 1.5, and 2....
Hervault M, Huys R, Buisson JC, Francheteau M, Siguier P, Zanone PG.In order to gauge the executive processes underlying adaptive behavior, a central criterion in psychology is the extent to which experimental findings generalize across response types. The latency of two major acts of control, action initiation and inhibition, was evaluated using a stop-signal paradigm with two response types, involving either a finger key-pressing or a wrist pen-swiping response. In both conditions, 40 participants were instructed to respond quickly to a GO stimulus but to cancel their responses when a STOP signal was presented, which occurred randomly in 25% of the trials. T...
Bolat D, Bahar S, Tipirdamaz S, Selcuk ML.The aims of this study were to determine the total volume of the horse kidney and volume fractions of its functional subcomponents (cortex, medulla, renal pelvis) using stereological methods and investigate any possible difference in the functional subcomponents of the right and left kidneys that may arise from differences in shape. The study was carried out on the kidneys of 5 horses of different breed and sex. The weight of the kidneys was measured by a digital scale, and kidney volume was calculated by Archimedes' principle. Total kidney volume and volume fractions of subcomponents of the r...
Katwa LC, Johnson PJ, Ganjam VK, Kreeger JM, Messer NT.Biosynthesis of endothelin-1 (ET-1), the most potent endogenous vasoconstrictor yet identified, is increased following myocardial infarction (MI) in man. Pathological events which occur in the connective tissues of the equine hoof during laminitis are similar in some respects, to changes occurring in the myocardial connective tissues following MI in man. The objective of this study was to determine whether ET-1 expression in connective tissues obtained from the hoof of laminitic horses is increased compared with tissues obtained from healthy horses. Expression of ET-1 in connective tissues of ...
Labadia A, Rivera L, Costa G, García-Sacristán A.The presence of both alpha and beta adrenergic receptors in the caudal third ureter of the horse were studied in vitro under isometric conditions using adrenergic agonist and antagonist drugs. Isoprenaline and the beta 2- stimulating agent, salbutamol, elicited relaxation of the ureter smooth muscle strips. The responses were not affected by the beta 1- blocking agent, practolol, but were totally abolished by propranolol and the beta 2- blocking agent, butoxamine. The stimulation of alpha-adrenergic receptors with noradrenaline and phenylephrine evoked a contractile effect which was totally in...
van Doorn DC, Kooyman FN, Eysker M, Hodgkinson JE, Wagenaar JA, Ploeger HW.Cyathostomins are considered to be the primary helminth pathogen of horses and macrocyclic lactones (ML) are the most frequently used anthelmintics. Therefore, ML resistance is a serious threat for the control of these parasites. In the present study ivermectin resistant cyathostomin L3 were in vitro selected, using a reiterative larval migration inhibition assay (rLMIA) and differentiated by reverse line blot (RLB). Larvae were obtained from two populations, one from a never treated, free-roaming horse population in the nature reserve Oostvaardersplassen (OVP) and the other from regularly ive...
Lorenzo-Figueras M, Morisset SM, Morisset J, Lainé J, Merritt AM.To measure concentrations and activities of major digestive enzymes in healthy equine pancreatic tissue. Methods: 7 adult horses with normal pancreatic tissues. Methods: Small pieces of pancreatic tissue were collected immediately after euthanasia, immersed in liquid nitrogen, and maintained at -80 degrees C until analyzed. Concentrations and activities of amylase, lipase, chymotrypsin, trypsin, and elastase were determined by use of a microtiter technique. Relative pancreatic protein concentrations were determined by use of bovine serum albumin as the standard. Pancreatic DNA was extracted an...
Kankavi O, Ata A, Akif Ciftcioglu M.The presence of surface-active material in the lung alveolus has been known for several decades as being essential for normal lung function. The host defense and controlling inflammatory processes of the lung are the major functions of SP-A and SP-D. SP-A and SP-D were originally demonstrated in alveolar type II cells, but recent studies have shown extrapulmonary expression of SP-A and SP-D indicating systemic roles of these proteins. Present study describes the presence of SP-A and SP-D in the stallion genital tract, prepuce, prostate, testis, and seminal vesicle using Western blotting and im...
Clarke LL, Roberts MC, Grubb BR, Argenzio RA.In ponies fed concentrated (pelleted) meals, postprandial increases of plasma aldosterone have been temporally associated with a decrease in colonic fluid volume that parallels the conclusion of postfeeding fermentation. To determine the significance of short-term increases of plasma aldosterone on the rate of colonic Na absorption, in vitro transport studies were conducted on the mucosae of three morphologically distinct colonic segments (i.e., ventral, dorsal, and small colons) from ponies infused with a high physiological concentration of aldosterone for an 8-h period. In control ponies, ba...
Hernández-Avilés C, Ramírez-Agámez L, Varner DD, Love CC.The current study determined the effect of the egg-yolk (phospholipid source) level (egg yolk [20% EY] vs. skim-milk + egg yolk [SM + 2% EY]), cryoprotectant (glycerol [Gly] vs. glycerol + methylformamide [Gly + MF]), and pre-freeze cooling rate (-0.1 vs. -1 vs. -5 °C/min) on post-thaw stallion sperm quality. In Experiment 1, ejaculates (n = 27) from 9 stallions (3 ejaculates each) with varied sperm quality (High, Average, or Low) were frozen in EY-Gly, SMEY-Gly, EY-Gly + MF, or SMEY-Gly + MF extenders. Sperm in each group were cooled from 22° to 5°C using either -0.1 °C/min or -1 ...
Bernoco MM, Liu IK, Willits NH.Six foals were deprived of colostrum for the first 36 hours after birth and, instead, received reconstituted powdered milk. Five control foals suckled their dams naturally. Blood samples were obtained from all the foals after birth and at approximately weekly intervals until at least 5.5 months of age. Sera were analyzed for hemolytic complement activity, complement component C3, and correlating IgG concentration. Hemolytic complement (P = 0.0145) and C3 (P = 0.0002) values were significantly higher in colostrum-deprived foals (CDF) than in naturally nursed foals at 2 to 5 days of age. In addi...
Townsend WM, Wasserman N, Jacobi S.Intraocular lenses (IOLs) have been implanted in adult equine eyes after cataract surgery. Foals and weanlings comprise a large proportion of those horses undergoing cataract surgery. Due to potential differences in the size and corneal curvature of the juvenile eye, it is not currently known whether implantation of adult IOLs is appropriate in foals and weanlings. The objective of the study was to measure the anterior chamber depth (ACD), central lens thickness (CLT), vitreous chamber depth (VCD), axial globe length (AGL) and corneal curvature of horses less than one year of age. The axial di...
Koenig JB, Martin CE, Nykamp SG, Mintchev MP.To evaluate whether changes in myoelectrical activity in the cecum and large colon of horses can be detected via multichannel electrointestinography (EIG). Methods: 6 healthy mature horses. Methods: Each horse underwent 3 EIG procedures. Intestinal myoelectrical activity (cecum and large colon) was recorded during a 20-minute period following i.v. administration of physiologic saline (0.9% NaCl) solution (20 mL; baseline), erythromycin lactobionate (0.5 mg/kg), or detomidine (0.015 mg/kg); intestinal contractions were concurrently viewed via B-mode ultrasonography. By use of computer software,...
De Angelis E, Barilli A, Saleri R, Rotoli BM, Ravanetti F, Ferrari F, Ferrari L, Martelli P, Dall'Asta V, Borghetti P.Due to the importance of joint disease and ostearthritis (OA) in equine athletes, new regenerative treatments to improve articular cartilage repair after damage are gaining relevance. Chondrocyte de-differentiation, an important pathogenetic mechanism in OA, is a limiting factor when differentiated articular chondrocytes are used for cell-based therapies. Current research focuses on the prevention of this de-differentiation and/or on the re-differentiation of chondrocytes by employing different strategies in vitro and in vivo. Articular chondrocytes normally live in a condition of higher osmol...
Marr KA, Foster AP, Lees P, Cunningham FM, Page CP.The effect of antigen challenge on the state of activation of peripheral blood neutrophils from horses with chronic obstructive pulmonary disease (COPD) has been determined by measuring neutrophil superoxide anion formation. Prior to a seven-hour antigen challenge superoxide anion production by neutrophils from asymptomatic horses with COPD and normal horses in response to platelet activating factor (PAF) (with and without cytochalasin B), serum treated zymosan (STZ) and phorbol myristate acetate (PMA) was similar. Agonist-induced superoxide production by neutrophils from symptomatic COPD and ...
Bugno M, Zabek T, Golonka P, Pieńkowska-Schelling A, Schelling C, Słota E.Cytogenetic and molecular genetic studies of an intersex horse have been carried out. The investigated animal had overall male body conformation; however, its external genitalia consisted of incompletely developed vulva and penis. The X and Y chromosome painting probes detected three cell lines in the examined horse: 63,X, 64,XX and 65,XX with a fragment of a Y chromosome (del Y). The DNA analysis with the PCR and PCR/RFLP methods showed absence of SRY,AMELY and ZFY genes as well as of six Y microsatellite markers (YM2, YP9, YJ10, YE1, YH12, and YA16). These results suggest that the Y chromoso...
Sabban S, Ye H, Helm B.The interaction of IgE with its high-affinity Fc receptor (FcεRI) followed by an antigenic challenge is the principal pathway in IgE mediated allergic reactions. As a consequence of the high affinity binding between IgE and FcεRI, along with the continuous production of IgE by B cells, allergies usually persist throughout life, with currently no permanent cure available. Horses, especially race horses, which are commonly inbred, are a species of mammals that are very prone to the development of hypersensitivity responses, which can seriously affect their performance. Physiological responses ...
Yarnell K, Purcell RS, Walker SL.Adrenal activity can be assessed in the equine species by analysis of feces for corticosterone metabolites. During a potentially aversive situation, corticotrophin releasing hormone (CRH) is released from the hypothalamus in the brain. This stimulates the release of adrenocorticotrophic hormone (ACTH) from the pituitary gland, which in turn stimulates release of glucocorticoids from the adrenal gland. In horses the glucocorticoid corticosterone is responsible for several adaptations needed to support equine flight behaviour and subsequent removal from the aversive situation. Corticosterone met...
Kaido M, Kilborne AH, Sizemore JL, Reisbig NA, Aarnes TK, Bertone AL.OBJECTIVE To analyze the effects of vertical force peak (VFP) of repition within trials and between trial sessions in horses with naturally occurring appendicular lameness. ANIMALS 20 lame horses acclimated to trotting over a force plate. PROCEDURES Kinetic gait data were collected by use of a force plate regarding affected and contralateral limbs of lame horses that completed 5 valid repetitions in each of 5 sessions performed at 0, 3, 6, 12, and 24 hours, constituting 1 trial/horse. Data were compared within and among repetitions and sessions, and factors influencing VFP values were identifi...
