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.
Verwilghen D, Busoni V, Gangl M, Franck T, Lejeune JP, Vanderheyden L, Detilleux J, Grulke S, Deberg M, Henrotin Y, Serteyn D.Establishing the osteoarticular status of the horse is often performed by means of radiological screening of the animals. Widespread blood sampling could reveal to be an interesting alternative to this procedure which is time consuming and sometimes technically difficult. The aim of this study was to investigate the relationship between the radiological status of the horses and the levels of biochemical markers of cartilage degradation and synovial inflammation. A specific radiological scoring and classification system was therefore developed and applied on 63 stallions presented for studbook ...
Marañón G, Manley W, Cayado P, GarcÃa C, de la Muela MS, Vara E.Colic could be accompanied by changes in the morphology and physiology of organs and tissues, such as the intestine. This process might be, at least in part, due to the accumulation of oxidative damage induced by reactive oxygen (ROS) and reactive nitrogen species (RNS), secondary to intestinal ischemia. Glutathione (GSH), being the major intracellular thiol, provides protection against oxidative injury. The aim of this study was to investigate whether ischemia-induced intestinal injury could be related with alterations in GSH metabolism. Results: Ischemia induced a significant increase in lip...
Brooks AC, Menzies-Gow NJ, Wheeler-Jones CP, Bailey SR, Elliott J, Cunningham FM.Lipopolysaccharide (LPS) can activate equine platelets directly or indirectly, via leukocyte-derived platelet activating factor (PAF). Thromboxane (Tx) production by LPS-stimulated equine platelets requires p38 MAPK and this kinase has been suggested as a therapeutic target in endotoxaemia. The present study has utilised selective inhibitors to investigate the role of p38 MAPK and two other kinases, phosphatidylinositol-3 kinase (PI3K) and protein kinase C (PKC), in regulating PAF-induced Tx production, aggregation and 5-HT release in equine platelets, and the modification of these responses b...
El-Maaty AM, Gabr FI.Sixteen Arab lactating mares belonging to Al-Zahraa Arab Horse Stud underwent two ultrasound examinations at 3 weeks interval starting from the day of demonstration of foaling heat. In addition, daily blood samples were collected from parturition until after exhibiting first postpartum estrus (day 11) with daily observation of estrous signs. Both leptin and estradiol hormones were assayed. Mean day of foaling heat was 8.9+/-0.9 day. Most mares came in foaling heat during days 9 and 10 had high conception rate compared to those who came in estrus earlier or later. Estradiol levels were high aft...
Basile M, Boivin S, Boutin A, Blois-Heulin C, Hausberger M, Lemasson A.Laterality is now known to be an ubiquitous phenomenon among the vertebrates. Particularly, laterality of auditory processing has been demonstrated in a variety of species, especially songbirds and primates. Such a hemispheric specialization has been shown to depend on factors such as sound structure, species specificity and types of stimuli. Much less is known on the possible influence of social familiarity although a few studies suggest such an influence. Here we tested the influence of the degree of familiarity on the laterality of the auditory response in the domestic horse. This species i...
Duehlmeier R, Hacker A, Widdel-Bigdely A, von Engelhardt W, Sallmann HP.Glucose homeostasis depends on insulin-regulated glucose uptake in the skeletal muscles and fat tissues via glucose transporter (GLUT) 4 translocation into cellular plasma membranes. The present study sought to elucidate GLUT4 expression, GLUT1 and GLUT4 translocation and glucose uptake in the skeletal muscles of Shetland ponies. Semitendinosus muscle explants were removed by open muscle biopsy from six Shetland pony geldings under general anaesthesia. The expression of GLUT4 was analysed by measuring muscle crude membrane (CM) GLUT4 protein contents. To determine the insulin-stimulated GLUT t...
Borzacchiello G, Mogavero S, De Vita G, Roperto S, Della Salda L, Roperto F.The equine sarcoid is the most common dermatologic neoplasm reported in horses. Bovine papillomavirus (BPV) types 1 and 2 are associated with sarcoids, in which the expression of the major transforming oncoprotein (E5) is often recorded. The transformation activity of the virus is due to the binding of the E5 to the platelet-derived growth factor beta receptor (PDGFbeta-r). In the present study, we show by Western blot in 4 sarcoid samples and 3 normal equine skin samples that the PDGFbeta-r is more phosphorylated in sarcoid tissue than in normal skin (P < .001). Furthermore, the physical i...
Reijerkerk EP, Visser EK, van Reenen CG, van der Kolk JH.To compare the effects of IV administration of various doses of ovine corticotrophin-releasing hormone (oCRH) on plasma and saliva cortisol concentrations in healthy horses and determine whether an oCRH challenge test protocol is valid for use in adult horses. Methods: 24 healthy Warmblood horses. PROCEDURES-Each horse received oCRH in saline (0.9% NaCl) via IV administration at a dose of 0 (control treatment), 0.01, 0.1, or 1.0 Mg/kg (6 horses/group). Jugular blood and saliva samples were collected simultaneously 15 minutes before and immediately prior to injection (baseline); data from these...
Shih AC, Giguère S, Sanchez LC, Valverde A, Jankunas HJ, Robertson SA.To compare cardiac output (CO) measured by lithium arterial pressure waveform analysis (PULSECO) and CO measured by transpulmonary pulse contour analysis (PICCO) in anesthetized foals, with CO measured by use of lithium dilution (LIDCO) considered the criterion-referenced standard. Methods: 6 neonatal (1- to 4-day-old) foals that weighed 38 to 45 kg. Procedures-Foals were anesthetized and instrumented to measure direct blood pressure, heart rate, arterial blood gases, and CO. The CO was measured by use of PULSECO, PICCO, and LIDCO techniques. Measurements were converted to specific CO (sCO) va...
Grange S, Duncan P, Gaillard JM.We investigated density dependence on the demographic parameters of a population of Camargue horses (Equus caballus), individually monitored and unmanaged for eight years. We also analysed the contributions of individual demographic parameters to changes in the population growth rates. The decrease in resources caused a loss of body condition. Adult male survival was not affected, but the survival of foals and adult females decreased with increasing density. Prime-aged females maintained high reproductive performance at high density, and their survival decreased. The higher survival of adult m...
Kamalov AA, Gukhikh GT, KirpatovskiÄ VI, ZaraÄskiÄ EI, Poltavtseva RA, Plotnikov EIu, Kudriavtsev IuV, Efremov EA, Obokhotov DA.The study of cell cultures enriched with stem and progenitor cells in the treatment of experimental hypergonadotropic hypogonadism was made on 30 white non-inbred rats with experimental cryptorchism who have undergone xenotransplantation of human fetal enriched cell cultures. Spermatogenic epithelium on histological sections was studied on day 14 and 28 after xenotransplantation with calculation of the spermatogenesis index. The fertility index was estimated for each of the groups. Transplantation of enriched cell cultures enhances efficacy of restoration of adequate germinogenic and spermatog...
Davies JA, Krebs GL, Barnes A, Pant I, McGrath PJ.A feeding trial involving four Thoroughbred race horses was undertaken to establish whether inclusion of grape seed extract (GSE) in the diet of horses undergoing mild exercise had any effects on their general health, intake and digestion. Supplementation with GSE had no effect on either feed or water intake of the horses and the supplement was readily palatable to the horses at all levels of inclusion. Feeding GSE caused no adverse effects in terms of animal health (temperature, pulse and respirations rates), and there were some positive effects related to a presumed alteration in fermentatio...
Spriet M, McKnight A.Three isolated equine limbs were imaged with a low-field magnetic resonance system with a vertical magnetic field. Each limb was scanned in multiple positions with mild variation of the angle between the magnetic field and the long axis of the limb. When the long axis of the limb was not perpendicular to the magnetic field, a linear hyperintense signal was present at the palmar aspect of one of the deep digital flexor tendon lobes, at the level of the navicular bone and collateral sesamoidean ligaments, in proton density and T1-weighted pulse sequences. With increased angulation of the limb, t...
Chalmers HJ, Yeager AE, Ducharme N.Dorsal displacement of the soft palate is an important cause of poor performance in racehorses, yet its etiology is not fully understood. Diagnosis requires treadmill videoendoscopy, which is not widely available. The relationship of the larynx, the hyoid apparatus, and the remainder of the skull may be important in predisposing horses to dorsal displacement of the soft palate. We hypothesized that this relationship could be accurately assessed in unsedated horses through ultrasonographic examination. Fifty-six racehorses presented for evaluation of poor performance were subjected to treadmill...
Brama PA, Holopainen J, van Weeren PR, Firth EC, Helminen HJ, Hyttinen MM.We investigated the effects of exercise-induced loading on the collagen network of equine articular cartilage. Collagen fibril architecture at a site (1) subjected to intermittent high-intensity loading was compared with that of an adjacent site (2) sustaining continuous low-level load. From horses exposed to forced exercise (CONDEX group) or not (PASTEX group), the spatial parallelism of fibrils and the orientation angle between fibrils and the surface at depths 9 microm apart through cartilage from surface to tidemark were determined using polarized light microscopy, and expressed as paralle...
Schauvliege S, Van den Eede A, Duchateau L, Pille F, Vlaminck L, Gasthuys F.To investigate the influence of calcium chloride (CaCl(2)) on the cardio-respiratory effects of enoximone in isoflurane anaesthetized ponies. Methods: Prospective consecutive experimental trial. Animals Six healthy ponies, weighing 287 +/- 55 kg were included in this study. Methods: After sedation (romifidine, 80 microg kg(-1)), anaesthesia was induced with midazolam (0.06 mg kg(-1)) and ketamine (2.2 mg kg(-1)) and maintained with isoflurane in oxygen. The ponies' lungs were ventilated to maintain normocapnia. After 90 minutes, a bolus of enoximone (0.5 mg kg(-1)) was administered, followed b...
Elfenbein JR, Sanchez LC, Robertson SA, Cole CA, Sams R.To evaluate the effects of detomidine on visceral and somatic nociception, heart and respiratory rates, sedation, and duodenal motility and to correlate these effects with serum detomidine concentrations. Methods: Nonrandomized, experimental trial. Methods: Five adult horses, each with a permanent gastric cannula weighing 534 +/- 46 kg. Methods: Visceral nociception was evaluated by colorectal (CRD) and duodenal distension (DD). The duodenal balloon was used to assess motility. Somatic nociception was assessed via thermal threshold (TT). Nose-to-ground (NTG) height was used as a measure of sed...
Rizzo A, Mutinati M, Spedicato M, Minoia G, Trisolini C, Punzi S, Roscino MT, Jirillo F, Sciorsci R.The beta-subunits of thyroid stimulating hormone (TSH) and human chorionic gonadotropin (hCG) share a high homology, just like the ectodomains of their receptors, do. As a consequence, hCG was shown to exert a thyrotropic action in humans and hamsters. This study aimed to investigate whether hCG, used to induce ovulation, displays a thyrotropic effect in the equine species too. Forty mares at estrus were divided in two groups; 20 were intravenously treated with sterile saline solution (NaCl 0.9%) (group A); 20 were intravenously treated with 4000 I.U. of hCG (group B). All the mares were artif...
DiMaio Knych HK, DeStefano Shields C, Buckpitt AR, Stanley SD.Substantial gaps exist in our knowledge of the metabolic clearance of therapeutic agents in horses. Accordingly, a cytochrome P450 monooxygenase in the 2C family was cloned from an equine liver, sequenced and expressed in a baculovirus expression system. Catalytic activities of the recombinant protein were measured with a number of substrates. The protein, assigned CYP2C92, displayed optimal catalytic activity with diclofenac using molar ratios of CYP2C92 to NADPH CYP450 reductase of 1:18. Addition of cytochrome b(5) to diclofenac incubations had no significant effect on metabolic turnover. CY...
GarcÃa-Rubio I, Fittipaldi M, Trandafir F, Van Doorslaer S.In this work, we show the extreme power of multifrequency HYSCORE (hyperfine sublevel correlation spectroscopy) techniques to unravel the hyperfine interactions of the electron spin with the remote nuclei in the heme site of high-spin ferric heme proteins. Horse heart aquo-metmyoglobin was used as a model system to demonstrate the power of these techniques. Experimental evidence was collected and assigned to protons of the proximal histidine ligand, to the mesoprotons of the heme ligand, and to two different protons of the distal water ligand. The latter difference relates to the stabilization...
Magee C, Foradori CD, Bruemmer JE, Arreguin-Arevalo JA, McCue PM, Handa RJ, Squires EL, Clay CM.The purpose of the present study was to evaluate the effects of kisspeptin (KiSS) on LH and FSH secretion in the seasonally estrous mare and to examine the distribution and connectivity of GnRH and KiSS neurons in the equine preoptic area (POA) and hypothalamus. The diestrous mare has a threshold serum gonadotropin response to iv rodent KiSS decapeptide (rKP-10) administration between 1.0 and 500 microg. Administration of 500 microg and 1.0 mg rKP-10 elicited peak, mean, and area under the curve LH and FSH responses indistinguishable to that of 25 microg GnRH iv, although a single iv injection...
Nourian AR, Mills PC, Pollitt CC.Microdialysis (MD) was used for continuous monitoring of the lamellar extracellular fluid (ECF) in six mature healthy Standardbred horses. MD probes were introduced into the lamellar tissue under local anaesthesia. Following intravenous injection of gentamicin (5mg/kg), MD and serum samples were collected for 24h and analysed using a sensitive ELISA test for gentamicin and fluorescence polarization immunoassay for urea concentrations. Calibration of probes was performed through in vivo urea recovery and in vitro gentamicin and urea recovery. Data obtained from different body compartments were ...
Bertolucci C, Giudice E, Fazio F, Piccione G.The present study was undertaken to investigate the existence of intraocular pressure (IOP) rhythms in athletic thoroughbred horses maintained under a 24 h cycle of light and darkness (LD) or under constant light (LL) or constant dark (DD) conditions. We identified an IOP circadian rhythm that is entrained to the 24 h LD cycle. IOP was low during the dark phase and high during the light phase, with a peak at the end of the light phase (ZT10). The circadian rhythm of IOP persisted in DD (with a peak at CT9.5), demonstrating an endogenous component in IOP rhythm. As previously shown in other mam...
Oosterlinck M, Pille F, Back W, Dewulf J, Gasthuys F.Subtle lameness in horses may be difficult to diagnose and methods to evaluate lameness objectively are useful when equine clinicians fail to reach a consensus. The aim of this study was to determine whether equine pressure plate measurements are repeatable when used to calculate forelimb loading (peak vertical pressure [PVP], peak vertical force [PVF], vertical impulse [VI]) and symmetry ratios, and to establish if these data are similar to the 'gold standard' force plate values. Since plate dimensions are relatively small, ponies were used to enable recordings to be taken from both forelimbs...
González-Fernández L, Ortega-Ferrusola C, Macias-Garcia B, Salido GM, Peña FJ, Tapia JA.Protein tyrosine kinases have important roles in spermatozoa; however, little is known about the presence and regulation in these cells of their counterparts in signaling, namely, protein tyrosine phosphatases (PTPs) and dual-specificity phosphatases (DSPs). The objectives of the present study were to identify PTPs and DSPs in boar, stallion, and dog spermatozoa; to characterize their subcellular distribution; and to investigate the roles of tyrosine phosphatases in maintenance of protein tyrosine phosphorylation level and in sperm motility. Using Western blotting with specific antibodies in b...
Lindsay AM, Zhang M, Mitchell Z, Holden MTG, Waller AS, Sutcliffe IC, Black GW.Streptococcus equi causes equine 'strangles'. Hyaluronate lyases, which degrade connective tissue hyaluronan and chondroitins, are thought to facilitate streptococcal invasion of the host. However, prophage-encoded hyaluronate lyases are hyaluronan-specific and are thought to be primarily involved in the degradation of the hyaluronan capsule of streptococci during bacteriophage infection. To understand the role of prophage-encoded hyaluronate lyases further, we have biochemically characterized such a hyaluronate lyase, SEQ2045 from S. equi, and have shown that it is produced during equine infe...
Mogielnicka-Brzozowska M, Fraser L, Dziekońska A, Gackowska K, Sobiewska M, Kuzborska A, Majewska AM, Filipowicz K, Kordan W.The aim of this study was to identify the proteoforms of albumin and kallikrein in stallion seminal plasma (SP), and to determine their correlations with sperm motility parameters. The experimental material consisted of ejaculates from 8 stallions, which were collected during the breeding and non-breeding seasons (BS and NBS, respectively). SP proteins were identified by 2-D PAGE and mass spectrometry (MALDI TOT/TOF MS). Sperm motility parameters were analyzed using the CASA system. Protein expression (integrated optical density-IOD) of albumin proteoforms 1 (ALB 1) and 2 (ALB 2) and kallikrei...
Villas-Boas JD, Dias DP, Trigo PI, Almeida NA, de Almeida FQ, de Medeiros MA.Startle is a fast response elicited by sudden acoustic, tactile, or visual stimuli in a variety of animals and in humans. As the magnitude of startle response can be modulated by external and internal variables, it can be a useful tool to study reaction to stress. Our study evaluated whether acupuncture can change cardiac autonomic modulation (heart rate variability); and behavioural (reactivity) and endocrine (cortisol levels) parameters in response to startle. Brazilian Sport horses (n = 6) were subjected to a model of startle in which an umbrella was abruptly opened near the horse. Before s...
Sasaki N, Yamada H.To evaluate the visibility of various portions of the small intestine in healthy horses using capsule endoscopy. Methods: Six healthy, conscious adult Thoroughbreds were restrained and an endoscopic capsule (PillCam SB capsule) was inserted into the oesophagus using an intranasal catheter aided by a guide wire. Water (500 mL) flushed the capsule down the gastrointestinal tract. Data were collected and stored in the recorder of the endoscopic system for 6 hours after capsule insertion and the images were evaluated using an image reader and scored using a visual analogue scale. Results: Capsule ...
Olsen SC, Coyne CP, Lowe BS, Pelletier N, Raub EM, Erickson HH.Four hours prior to exercise on a high-speed treadmill, 4 dosages of furosemide (0.25, 0.50, 1.0, and 2.0 mg/kg of body weight) and a control treatment (10 ml of 0.9% NaCl) were administered IV to 6 horses. Carotid arterial pressure (CAP), pulmonary arterial pressure (PAP), and heart rate were not different in resting horses before and 4 hours after furosemide administration. Furosemide at dosage of 2 mg/kg reduced resting right atrial pressure (RAP) 4 hours after furosemide injection. During exercise, increases in treadmill speed were associated with increases in RAP, CAP, PAP, and heart rate...
Hannan MA, Murase H, Sato F, Tsogtgerel M, Kawate N, Nambo Y.The peripheral blood concentrations of insulin-like peptide 3 (INSL3) have been detected in many mammalian species, but the level of INSL3 in horse remains unknown. The objectives were to develop a time-resolved fluorescence immunoassay (TRFIA) to detect INSL3 concentrations from horse blood as well as to determine the age-related and seasonal changes of plasma concentrations of INSL3 and testosterone from birth to early-puberty in Thoroughbred male horse (n = 11). Monthly blood sample and measurement of body weight, height, chest and cannon bone size were done from birth until 16 mo. Th...
Pauwels FE, McClure SR, Amin V, Van Sickle D, Evans RB.To measure changes in the modulus of elasticity (E) and describe histologic findings after extracorporeal shock wave therapy and radial pressure wave therapy on equine cortical bone specimens. Methods: 16 bone specimens from the proximodorsal cortex of an equine third metacarpal or metatarsal bone. Methods: Baseline E was determined by the density (p) and unidirectional ultrasound transmission velocity (C) of each specimen according to the equation E = pC2. Eight specimens were treated with 500 pulses of 0.15 mJ/mm2 of extracorporeal shock wave therapy, and 8 specimens were treated with 500 pu...
Silva CJFL, Trindade KLG, Cruz RKS, Manso HECCC, Coelho CS, Filho JDR, Nogueira CEW, Aragona F, Fazio F, Manso Filho HC.Erosions and gastric ulcers may be present in horses at any age and under different conditions of rearing and handling. In tropical regions, horses can feed on fruits rich in soluble carbohydrates, such as mangoes, but little is known about how these foods interact with their digestive systems. To test the hypothesis that the ingestion of ripe mangoes with peels could cause disturbances in the digestive processes of horses, an experiment was developed to monitor animals that had free access to ripe mangoes in their pasture areas. Horses (purebred Arabians, n = 5; ~340 kg, ~13 years) were evalu...
Pakkanen SA, Raekallio MR, Mykkänen AK, Salla KM, de Vries A, Vuorilehto L, Scheinin M, Vainio OM.To investigate MK-467 as part of premedication in horses anaesthetized with isoflurane. Methods: Experimental, crossover study with a 14 day wash-out period. Methods: Seven healthy horses. Methods: The horses received either detomidine (20 μg kg(-1) IV) and butorphanol (20 μg kg(-1) IV) alone (DET) or with MK-467 (200 μg kg(-1) IV; DET + MK) as premedication. Anaesthesia was induced with ketamine (2.2 mg kg(-1) ) and midazolam (0.06 mg kg(-1) ) IV and maintained with isoflurane. Heart rate (HR), mean arterial pressure (MAP), end-tidal isoflurane concentration, end-tidal carbon ...
Mifune H, Suzuki S, Noda Y, Mohri S, Mochizuki K.In the pig, cattle and horse, the right and left atria and ventricles were examined by immunohistochemistry, and the right atrial and auricular cardiocytes were studied by transmission electron microscopy. Moreover, ANP-granules in the cardiocytes were analyzed by ultrastructural morphometry. Immunohistochemically, the most intensely ANP-reacted cardiocytes were localized in the right auricle, particularly more prominent in the pig and cattle than in the horse. Ultrastructurally, ANP-granules were located principally in the perinuclear region associated with the Golgi apparatus and throughout ...
Andrade FS, Facó LL, Ida KK, Silva LC, Fantoni DT, Ambrósio AM.To compare static compliance (C) and alveolar-arterial oxygen tension difference [P(a-a)O] between positive end-expiratory pressures (PEEP) of 7, 12 and 17 cmHO applied after an alveolar recruitment maneuver (RM) in isoflurane-anesthetized horses. Methods: Prospective, randomized, clinical study. Methods: A group of 30 healthy adult horses undergoing arthroscopic surgery. Methods: Animals in dorsal recumbency and mechanically ventilated with a tidal volume of 14 mL kg and 7 cmHO PEEP (control; n = 6) were subjected to an RM by increasing PEEP from 7 to 22 cmHO in 5 cmHO increments at 5 minute...
Targowski SP.Treatment of ponies with a single dose of prednisolone markedly reduced the number of blood lymphocytes. A decrease of the number of eosinophils was also observed. In contrast, the number of neutrophils significantly increased. These profound changes were temporary and returned to the pretreatment level within 48 h. The number of monocytes did not show any of the significant changes post-prednisolone treatment. The reactivity of the blood lymphocytes of these ponies, in vitro, to stimulation with phytohemagglutinin (PHA) or streptokinase-strepto-dornase (SK-SD) was measured by incorporation of...
Mungall BA, Pollitt CC.Cultured equine lamellar hoof explants secrete the pro-enzymes matrix metalloproteinase-2 (MMP-2, 72 kDa) and MMP-2 (92 kDa). Untreated explants remained intact when tested on a calibrated force transducer, but when treated with an MMP activator, developed "in-vitro laminitis", separating at the dermal-epidermal junction. Explants treated with the bacterial protease thermolysin separated dose-dependently; this was accompanied by activation of both MMP-2 and -9. Thermolysin-mediated MP activation did not occur in a cell-free system and was not inhibited by the addition of the MMP inhibitor and ...
Kalpokas I, Mattos RC, Cavestany D, MartÃnez MN, Perdigón F, Meikle A.The effect of side of corpus luteum on uterine gene expression and protein localization of estrogen receptor α (ERα) and progesterone receptor (PR) in healthy cyclic and pregnant mares 13 days after ovulation (day 0) was investigated. Transcervical biopsies were performed to collect endometrium ipsilateral and contralateral regarding the side of corpus luteum on day 13 post-ovulation in cyclic (n = 6) and pregnant (n = 6) mares. Blood samples were collected daily from day 0 until the day of biopsy for 17β-estradiol (E2) and progesterone (P4) determinations. Receptor expression was d...
Bourges-Abella N, Raymond-Letron I, Diquelou A, Guillot E, Regnier A, Trumel C.To describe the cells observed in conjunctival brush cytology (CBC) from normal horses and compare these findings with conjunctival structural histology so as to understand which cells are recovered from CBC. Methods: This study was divided into three parts. (1) Conjunctival brush smears were collected from 20 healthy horses on both eyes and a differential count on 300 cells was carried out on May Grünwald-Giemsa (MGG) smears. (2) A similar protocol was used for whole eyes from five horses obtained rapidly after death from a slaughterhouse. The eyes were then assessed for conjunctival histolo...
Rourke KM, Kohn CW, Levine AL, Rosol TJ, Toribio RE.Calcium has important physiological functions, and disorders of calcium homeostasis are frequent in horses. We have made important progress understanding equine calcium homeostasis; however, limited information on equine calcitonin (CT) is available, in part because of the lack of validated CT assays. To determine the CT response to high ionized calcium (Ca(2+)) concentrations in healthy horses, we induced hypercalcemia in 10 healthy horses using a calcium gluconate 23% solution (5mg/kg; 120 mL/500 kg horse) infused over 4 min. Four horses were infused with 120 mL of 0.9% NaCl and used as cont...
Fenstermaker RA, Farmerie TA, Clay CM, Hamernik DL, Nilson JH.Expression of the glycoprotein hormone alpha-subunit gene occurs in the pituitaries of all mammals and in the placentas of primates and horses. In humans, tandem cAMP response elements (CREs), located in the proximal promoter-regulatory region of the alpha-subunit gene, act together with an adjacent upstream regulatory element to confer placenta-specific expression. Here, we report that the alpha-subunit genes of Old World Monkeys contain a single functional CRE. This suggests that tandem CREs are unique to higher primates and humans and are not absolutely required for placenta-specific expres...
Zhang JJ, Muzs LZ, Boyle MS.In vitro fertilizing ability of stallion spermatozoa was assessed using horse follicular oocytes matured in vitro. After collection, stallion spermatozoa were either: 1) washed and incubated in TALP medium with 3 mg/ml bovine serum albumin (BSA) and 10 micrograms/ml heparin for 4h, 2) washed and incubated in TALP with 3 mg/ml BSA for 3 h and cultured for a further 1 h with 1 mM caffeine and 5 mM dbcAMP, 3) washed and incubated in TALP medium with 3 mg/ml BSA at pH 7.9-8.2 for 2-4 h, or 4) diluted and incubated in TALP medium with 10 mg/ml BSA and 7.14 microM calcium ionophore A 23187 for 5-10 ...
Elliott J.Rings of equine digital vein examined under conditions of isometric tension recording constricted to alpha-adrenoceptor agonists with an order of potency of 5-bromo-6-[2-imidazolin-2-yl-amino]-quinoxaline bitartrate (UK 14304) = noradrenaline > 6-Allyl-2-amino-5,6,7,8-tetrahydro-4H-thiazolo-(4,5-d) azepine (BHT-920) > phenylephrine > dopamine > methoxamine. The maximum force generated was greatest for the non-selective agonist noradrenaline and lowest for the alpha2-selective agonist BHT-920 with the other agonists between these two extremes. Selective inactivation of alpha1-adreno...
Mama KR, Pascoe PJ, Steffey EP, Kollias-Baker C.To characterize responses associated with two 1-hour total intravenous anesthesia techniques in horses. Methods: 6 mature, healthy mares. Methods: Each horse was anesthetized 3 times. Treatment order was determined by a series of Latin squares. After baseline measurements and instrumentation, horses were given xylazine (XYL) i.v.; anesthesia was induced 5 minutes later with 10% guaifenesin given i.v., then either ketamine (KET) or propofol (PRO) was given i.v. After anesthesia induction, each horse received an infusion of XYL and either KET or a low or high dose of PRO. Cardiopulmonary variabl...
Arbabi V, Pouran B, Weinans H, Zadpoor AA.Investigation of the solute transfer across articular cartilage and subchondral bone plate could nurture the understanding of the mechanisms of osteoarthritis (OA) progression. In the current study, we approached the transport of neutral solutes in human (slight OA) and equine (healthy) samples using both computed tomography and biphasic-solute finite element modeling. We developed a multi-zone biphasic-solute finite element model (FEM) accounting for the inhomogeneity of articular cartilage (superficial, middle and deep zones) and subchondral bone plate. Fitting the FEM model to the concentra...
Richardson JD, Lane JG, Waldron KR.It is widely accepted that the age of a horse can be determined from an examination of its teeth, but there is no evidence that the accuracy of the systems of ageing used has been validated. A dental record was made of 80 horses of known age. There was a good correlation between the actual and apparent age of the horses up to five years, but older horses showed much greater variability and accuracy declined markedly after 11 years of age. The disappearance of the 'cup', but not the 'mark', proved to be one of the more reliable features. The average age at which the dental star appeared was one...
Kwirant LADA, De La Corte FD, Cantarelli C, Cargnelutti JF, Martins M, Cabral MW, Maciel N, Rubin MIB.Equine platelet-rich plasma (PRP) has been used in horses to repair bone, articular and tendinous lesions, laminitis, and even endometritis. However, platelets have a very limited lifespan, which makes it difficult to prepare and use PRP, except in loco. With the aim to produce PRP with higher platelet viability for clinical purposes, the effects of the cryoprotectants dimethyl sulfoxide (DMSO) and trehalose were evaluated on cooled (4°C) and cryopreserved (-196°C) equine PRP. The protocols of cooling and cryopreservation were performed independently, comparing the following treatments: fres...
Caple IW, Edwards SJ, Forsyth WM, Whiteley P, Selth RH, Fulton LJ.The activity of glutathione peroxidase, a selenium containing enzyme, was measured in the blood of horses to determine its usefulness as an indicator of selenium status. In 15 horses the enzyme activity was positively related to the blood selenium concentration (P less than .001, r-0.98) over the range of enzyme activities of 8.2 to 140 units (mumoles NADP-oxidised/min/gHb) and selenium concentrations of 0.24 to 2.74 mumol/l. In a group of 8 horses which 2 foals had died with lesions of muscular dystrophy the enzyme activity increased from a mean of 11.8 units before treatment with selenium to...
Decloedt A, de Clercq D, van der Vekens N, Verheyen T, Ven S, van Loon G.Shortening of atrial fibrillation cycle length (AFCL) is a marker of atrial electrical remodelling due to atrial fibrillation (AF). Objective: To investigate the effect of administration of detomidine on AFCL measured invasively from an intra-atrial electrogram (AFCLEGM) and noninvasively by tissue Doppler imaging (AFCLTDI). We hypothesised that detomidine would have no effect on AFCL but would improve the ease of TDI measurements and facilitate noninvasive AFCL determination. Methods: Prospective clinical study. Methods: Measurements were performed before and after i.v. administration of 7.5â...
Semrad SD, Sams RA, Ashcraft SM.Age and species reportedly affect the pharmacokinetic variables of nonsteroidal anti-inflammatory drugs. We determined the effect of age on flunixin pharmacokinetic variables in foals during the first month of life. We also estimated the physiologic activity of the drug in neonatal foals by determining the effect of flunixin on thromboxane production during clotting of blood taken from the foals. Flunixin disposition and clearance were determined after IV administration of 1.1 mg of drug/kg of body weight to 5 healthy foals when they were 24 to 28 hours, 10 to 11 days, and 27 to 28 days old. T...
Nieto-Olmedo P, MartÃn-Cano FE, Gaitskell-Phillips G, Ortiz-RodrÃguez JM, Peña FJ, Ortega-Ferrusola C.In order to determine whether differences in uterine blood flow between pregnant and non-pregnant mares can be used to predict the presence of the equine embryo prior to flushing in an embryo transfer program, power Doppler ultrasonography was used on a total of 52 mares on days 7 or 8 post-ovulation. Computer analysis of Doppler images was subsequently performed using ImageJ v1.48 software. Vascular perfusion of the endometrium was analyzed using spot meter techniques, measuring mean pixel intensity and area of blood flow. Mares with positive flushings presented a higher uterine blood flow ar...
Magdesian KG, Fielding CL, Rhodes DM, Ruby RE.To evaluate selected hemodynamic, blood gas, and biochemical responses to mild to moderate acute blood loss in standing, awake horses. Methods: Prospective study. Methods: 7 healthy mares. Methods: Each horse was restrained in standing stocks, and its head was maintained in a neutral position; sedatives and tranquilizers were not administered. During a 1-hour period, blood was collected into collection bags by use of a suction pump. The rate of blood collection was approximately 16 mL/kg/h (7.3 mL/lb/h). Thirty minutes after blood collection, the blood was readministered at the same rate. Cent...
Hinrichsen SL, Yuen KY, Dryburgh EL, Bertin FR, Stewart AJ.Pituitary pars intermedia dysfunction (PPID) is diagnosed by increased basal or post thyrotropin-releasing hormone (TRH) stimulation ACTH concentrations. ACTH is known to be unstable; however, the effect of different temperatures and TRH stimulation on equine ACTH stability is poorly described. In total, 15 horses, including 8 PPID positive (ACTH > 35 pg/mL at baseline or >65 pg/mL 30 min after TRH stimulation), were divided into 2 groups: 9, including 5 PPID positive, with basal ACTH concentrations and 6, including 3 PPID positive, with post TRH stimulation ACTH concentrations. Whole bl...
Loublier C, Taminiau B, Heinen J, Lecoq L, Amory H, Daube G, Cesarini C.Fecal microbiota transplantation (FMT) has been used empirically for decades in equine medicine to treat intestinal dysbiosis but evidence-based information is scarce. This in vitro study aimed at assessing the effect of a commonly used pre-FMT processing method on the bacterial composition and viability of the fecal filtrate. Three samples of fresh equine manure (T0) were processed identically: the initial manure was mixed with 1 L of lukewarm water and chopped using an immersion blender to obtain a mixture (T1), which was left uncovered during 30 min (T2) and percolated through a sieve to ob...
