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'Grady SE, Poupard DA.Adherence to the basic principles of physiologic horseshoeing is essential to maintaining hoof health and soundness. Most horses do not require special trimming or shoeing techniques. Becoming familiar with a few basic concepts can help the veterinarian to recognize when changes in trimming or shoeing might be expected to help the performance of a sound horse or might help to restore the performance of one that is lame. Sound physiologic horseshoeing can only be achieved by a thorough knowledge of, strict adherence to, and skillful application of basic principles, such as hoof angle, HPA, and ...
Zarucco L, Swanstrom MD, Driessen B, Hawkins D, Hubbard M, Steffey EP, Stover SM.To develop and test an experimental model for in vivo short-term recording of peak isometric forces of the digital flexor muscles in the forelimb of adult horses. Methods: In vivo experimental study. Methods: Four healthy, anesthetized, adult Thoroughbred horses (3 to 7 years old; 527 +/- 87 kg) Methods: In dorsal recumbency, ulnar and median nerves were exposed and instrumented with insulated bipolar cuff stimulation electrodes for later connection to an electrical stimulator. In left lateral recumbency, a biplanar fixator was applied to the right humerus and a custom-made, rigid, aluminum fr...
McD￮ LA, Anderson GI.To compare the osteogenic potential of cancellous bone of conventional graft sites with that of one nonconventional site (fourth coccygeal vertebra) and to investigate the tibial periosteum as a donor site with respect to osteogenic potential. Methods: In vitro osteogenic cell culture system. Methods: Eight adult horses. Methods: Cancellous bone or tibial periosteum was aseptically collected and cut into bone chips or periosteal strips of 1 to 2 mm(3) for primary explant cultures. After 2 weeks, primary tissue cultures that yielded a population of osteogenic cells were counted and subcultured ...
Weijs W, Dingboom E, van Ginkel F.The contribution to total variance of different error sources in fibre type counts of equine gluteus medius muscle biopsies was determined to quantify and possibly improve the resolution of the method. Fibre types were defined on the basis of myosin heavy chain immunostaining. Errors were determined at levels: (1) positioning the insertion channel, (2) positioning the needle tip (3) biopsy heterogeneity (4) observer interpretation. Errors at levels 1 and 2 were considerable. Confidence intervals for individual observations were +/- 10-15%. In longitudinal studies a group size of 4 animals is n...
Boerboom D, Brown KA, Vaillancourt D, Poitras P, Goff AK, Watanabe K, Doré M, Sirois J.Luteolysis in domestic species is mediated by the release of luteolytic pulses of prostaglandin (PG) F(2alpha) by the uterus at the end of diestrus, which must be suppressed by the conceptus to permit maternal recognition of pregnancy. In many species, including the horse, both the conceptus and the endometrium also synthesize PGE(2), which may antagonize PGF(2alpha) by playing a luteotropic and/or antiluteolytic role. While the release of PGE(2) and PGF(2alpha) by the equine endometrium in late diestrus and early pregnancy has been previously studied, the underlying prostaglandin synthase gen...
Mansour GD, Henry M, Ferreira AM.This study was designed to identify the distribution of type IV collagen, laminin, and fibronectin with an avidin-biotin method in sections of equine endometrial samples, fixed in Bouin's solution and embedded in paraffin wax. Thirty endometrial biopsies were collected at three different stages of the oestrous cycle. The basement membrane of luminal epithelium reacted positively with antibody against type IV collagen. Both type IV collagen and laminin were found in the basement membranes of endometrial glands, and fibronectin occurred diffusely in the interstitial tissue. Blood vessels express...
Fazio F, Ferrantelli V, Piccione G, Caola G.In the athletic horse, the efficiency of physical exercise during activity is strictly
connected to several organic–functional characteristics. Among these, cardiovascular
function takes a primary role in determining the quality of performance. The morphological and functional changes occurring in the cardiovascular system during physical
exercise are due to the increasing demand required to deal with intense muscular
activity. Thus, the cardiovascular physiological response to physical exercise is characterized both by transitory modifications and adjustments that are similar in both
t...
Carluccio A, Zedda MT, Schiaffino GM, Pirino S, Pau S.Testicular biopsy is one of the supplementary examinations performed in the course
of andrological testing. In veterinary medicine, it is seldom used in low-fertility or
sterility testing, or in the investigation of suspected cancer. Biopsies are discouraged
in horses in particular, since they may result in testicular sclerosis and atrophy
(Galina, 1971; Smith, 1974; Marusi and Corradi, 1989; Varner, 1991; Del Vento et al.,
1992; Threlfall and Lopate, 1993; Roser, 2000). In humans (Foresta and Varotto,
1992; Foresta et al., 1992; Kessaris et al., 1995; Harrington et al., 1996) good resul...
Fazio E, Ferlazzo A.Domestic animals are transported for a variety of reasons including breeding, biomedical purposes, slaughter and, in the case of sporting horses, for competitions, pleasure activities or ceremonial proceedings. Studies to determine the amount of stress on farm animals during transport often have highly variable results and are difficult to interpret. The reaction of animals to stressors depends on the duration and intensity of the stressors, the animal's previous experience, its physiological status and the immediate environmental restraints. Behavioural, haematological, haematochemical, physi...
Ito S, Hobo S, Kasashima Y.To evaluate the effects of compression atelectasis on the composition of pulmonary secretions in anesthetized horses, cytological and biochemical examinations were performed on bronchoalveolar lavage (BAL) fluids obtained from both dependent and independent lung regions. Six horses were anesthetized with isoflurane and oxygen for 120 min, and were positioned in right lateral recumbency. Percentage of neutrophils and total protein concentration in BAL fluids significantly increased at the end of anesthesia, and total phosphorous concentration significantly decreased at 72 hr after anesthesia in...
Brown DJ, Rush JE, MacGregor J, Ross JN, Brewer B, Rand WM.A novel method for quantitative echocardiographic interpretations is introduced based on the calculation of ratio indices in which each raw M-mode measurement is divided by the aortic root dimension (Ao). "Aorta-based" indices were calculated with the animal's measured aortic root dimension (Ao(m)) as the length standard. Conversely, "weight-based" indices employed an idealized estimate of aortic dimension (Ao(w)) with a weighted least squares linear regression against the cube root of body weight (Ao(w) = kW(1/3)). Use of these indices circumvented undesirable statistical characteristics inhe...
Bedford SJ, Kurokawa M, Hinrichs K, Fissore RA.In oocytes from all mammalian species studied to date, fertilization by a spermatozoon induces intracellular calcium ([Ca(2+)](i)) oscillations that are crucial for appropriate oocyte activation and embryonic development. Such patterns are species-specific and have not yet been elucidated in horses; it is also not known whether equine oocytes respond with transient [Ca(2+)](i) oscillations when fertilized or treated with parthenogenetic agents. Therefore, the aims of this study were: (i) to characterize the activity of equine sperm extracts microinjected into mouse oocytes; (ii) to ascertain i...
Martoriati A, Caillaud M, Goudet G, Gérard N.Interleukin 1 beta (IL-1 beta) inhibits the LH-induced resumption of meiosis of equine oocytes in vitro. The present study was performed to clarify this inhibitory effect of IL-1 beta by testing increasing concentrations of IL-1 beta, and by measuring the effect of addition of IL-1 receptor antagonist (IL-1RA) to the culture medium. The effect of IL-1 beta on epidermal growth factor (EGF)-induced resumption of meiosis was also studied. Cumulus-oocyte complexes (COCs) were collected from subordinate follicles on ovaries obtained from an abattoir. In five distinct experiments, COCs were cultured...
Ainsworth DM, Grünig G, Matychak MB, Young J, Wagner B, Erb HN, Antczak DF.In horses prone to developing recurrent airway obstruction (RAO), we tested the hypotheses that the cytokine profile in the bronchoalveolar lavage (BAL) cells of affected horses would reflect a polarized Th-2 response; that cytokine and chemokine alterations would occur within 24 h of allergen exposure; and that allergen exposure would induce alterations in the expression of the transcription factor t-bet (t-box-expressed in T-cells). The expression levels of interleukin-4 (IL-4), IL-13, Interferon-gamma (IFN-gamma), t-bet, IL-8 and granulocyte-macrophage colony stimulating factor (GM-CSF) wer...
Greenaway EC, Sepulveda MF, Cunningham FM, Goode NT.Eosinophils have been implicated in the pathogenesis of the seasonal equine allergic skin disease, sweet itch. Protein kinase C (PKC) is involved in regulating eosinophil function and antigen challenge has been reported to alter PKC isotype expression in blood eosinophils from allergic human subjects. Here we have compared the pattern of PKC isotype expression in eosinophils from sweet itch ponies with that in cells from normal ponies both during the active and inactive phases of the disease. A role for PKC in histamine-induced eosinophil activation was also investigated. Conventional PKCs alp...
Donadeu FX, Ginther OJ.The role of estradiol and inhibin in suppression of FSH and LH during the initiation of follicle deviation was examined in mares. In Experiment 1, the two largest follicles (F1, F2) were retained during a wave and the rest were ablated as they reached > or =10 mm. The largest follicle was left intact (control, n=12) or was ablated when it reached > or =20.0 mm (Day 0; expected beginning of deviation). The second largest follicle continued growing (n=9) or regressed (n=4) after F1 ablation. Circulating estradiol and total inhibin decreased after Day 0 in the F2-regressing group, whereas e...
Warnke C, Tuchscherer A, Alm H, Kanitz W, Blottner S, Torner H.The aim of the study was to compare different types of movement pattern and velocities of stallion spermatozoa depending on cryopreservation during breeding and non-breeding season. Ejaculates were collected from four stallions during May (n = 24) and December (n = 24). Parameters of sperm movement were evaluated by computer-aided sperm analysis (CASA) system, and included percentages of motile spermatozoa, different patterns of motility, the velocity, linearity (LIN), amplitude of lateral head displacement (ALH) and beat-cross frequency (BCF). In winter the average percentages of motility wer...
Bragulla H.Fetal development of the unique papillary body and its localized peculiarities in the equine hoof are described based on the study of 51 fetuses, nine newborn foals, and five adult horses. The shape and dimensions of the dermal papillae and lamellae have a formative influence on the structure and physical quality of the corneous hoof capsule with its horn tubules and lamellae. The size and arrangement of these horn structures determine the mechanical quality of hoof horn. Proper horn quality is a prerequisite for the various functions of the hoof capsule, such as protecting the living dermis s...
Brown JA, Derksen FJ, Stick JA, Hartmann WM, Robinson NE.Show and performance horse with laryngeal hemiplegia (LH) often present for excessive respiratory noise rather than significant exercise intolerance. Therefore, the goal of surgery in these horses is to reduce respiratory noise but there are no quantitative studies evaluating the effect of any upper-airway surgery in LH-affected horses. Objective: To determine whether bilateral ventriculocordectomy (VC) reduces respiratory noise in exercising horses with laryngeal hemiplegia. Methods: Six Standardbred horses with normal upper airways were used in this study. Respiratory sounds and inspiratory ...
Kindig CA, Ramsel C, McDonough P, Poole DC, Erickson HH.Capillary stress failure-induced (exercise-induced) pulmonary haemorrhage (EIPH) during intense running in horses is thought to involve both intravascular (i.e. mean pulmonary arterial pressure [Ppa] > 100 mmHg) and extravascular (e.g. negative inspiratory pressure swings) mechanisms. Objective: That inclined running would reduce breathing frequency (coupled to stride frequency) and increase tidal volume thus increasing lung volume changes and intrapleural pressure swings resulting in more pronounced EIPH. Methods: Six Thoroughbred horses were run to volitional fatigue (incremental step tes...
Baumber J, Sabeur K, Vo A, Ball BA.The objective of this study was to examine the influence of reactive oxygen species (ROS) on equine sperm capacitation. Motile equine spermatozoa were separated on a discontinuous Percoll gradient, resuspended at 10 x 10(6)ml in Tyrode's medium supplemented with BSA (0.5%) and polyvinyl alcohol (0.5%) and incubated at 39 degrees C for 2h with or without the xanthine (X; 0.1mM)-xanthine oxidase (XO; 0.01 U/ml) system or NADPH (0.25 mM). The importance of hydrogen peroxide or superoxide for capacitation was determined by the addition of catalase (CAT; 150 U/ml) or superoxide dismutase (SOD; 150 ...
Vervuert I, Coenen M, Bothe C.This study was conducted to evaluate the effects of different oat processing techniques on the plasma glucose and insulin response in horses. In a cross-over design, six horses (ages 4-15 years, mean body weight+/-SD: 450+/-37 kg) were fed in random order: untreated oats, finely ground, steam-flaked and popped oats. The total oat intake varied between 1.05-1.5 kg/day, and the amount of diet was adjusted to a starch content of 630 g starch per day and horse (1.2-1.5 g starch/kg BW/day). During the stabilization period of 10 days, horses additionally received 6 kg grass hay. Following this adapt...
Carrington EF, Desautels M, Naylor JM.Catecholamines are important lipolytic agents in horses and ponies but the nature of the adrenergic receptor subtype distribution in their adipocytes is uncertain. A first objective was to identify the beta-adrenergic receptor subtype(s) present in adipocytes from horses and ponies. A second objective was to evaluate if the lipolytic responsiveness of isolated adipocytes to beta-adrenergic agonists is altered during lactation, a condition known to affect markedly maternal fat metabolism. Isoproterenol and salbutamol elicited strong lipolytic responses in adipocytes isolated from horse and pony...
Ferrer MS, Miller LMJ.Antisperm antibodies (ASAs) have been associated with infertility in stallions. The objectives of this study were to investigate the frequency of ASA-positive semen samples in satisfactory and non-satisfactory breeder stallions, the association between ASA binding and semen quality, and factors that may affect the diagnosis. Breeding soundness examinations were performed in 21 stallions and the percentage of IgG- and IgA-bound spermatozoa was evaluated using flow cytometry. Median IgG and IgA binding did not differ between the first and second ejaculates. The percentage of IgA-bound spermatozo...
Otto KA, Voight S, Piepenbrock S, Deegen E, Short CE.The effects of noxious surgical stimulation on the electroencephalogram (EEG) in 15 horses anesthetized with isoflurane were evaluated during orthopedic (group 1) and soft tissue (group 2) procedures. The quantitative EEG variables theta/delta ratio (T/D), alpha/delta ratio (A/D), beta/delta ratio (B/D), median power frequency (MED), and 80% spectral edge frequency (SEF 80) recorded during Surgeries at 1.7% end-tidal concentration of isoflurane (ET(iso)) were compared with values from five nonstimulated control horses anesthetized at 1,7% ET(iso). The EEG variables T/D, A/D, MED, and SEF 80 fr...
Atwal OS, Singh B, Staempfli H, Minhas K.The pulmonary intravascular macrophages (PIMs) have been described in several species of animals. This study demonstrates for the first time that the equine lung has PIMs as resident phagocytes in its microvasculature. Their salient features such as globular surface coat, structures of the endocytic pathway, and related cell organelles closely resemble those of the calf, goat, and sheep. The exquisite organization of the coat globules in the form of a linear chain was structurally similar to the lipolytic lipase and the heparin-sensitive globular coat from PIMs of calf, goat, and sheep. Monast...
Bradbery AN, Coverdale JA, Vernon KL, Leatherwood JL, Arnold CE, Dabareiner RA, Kahn MK, Millican AA, Welsh TH.Seventeen yearling Quarter Horses were used in a randomized complete block design for a 56-d trial to determine ability of dietary CLA to mitigate joint inflammation and alter cartilage turnover following an inflammatory insult. Horses were blocked by age, sex, and BW, and randomly assigned to dietary treatments consisting of commercial concentrate offered at 1% BW (as-fed) supplemented with either 1% soybean oil (CON; n = 6), 0.5% soybean oil and 0.5% CLA (LOW; n = 5; 55% purity; Lutalin, BASF Corp., Florham Park, NJ), or 1% CLA (HIGH; n = 6) top-dressed daily. Horses were fed individually ev...
Boucher JH, Ferguson EW, Wilhelmsen CL, Statham N, McMeekin RR.The erythrocytes of 14 conditioned horses participating in a 157-km endurance ride (requiring 14-21 h) were examined before the ride, immediately upon entering the 44-91-, and 130-km rest stops, and at the finish. At the first rest stop (44 km), the mean erythrocyte count increased 41% (P less than 0.001), the mean hematocrit (Hct) increased 30% (P less than 0.001) and the mean hemoglobin (Hb) increased 33% ( P less than 0.001). Although subsequent mean erythrocyte counts, Hct, and Hb values remained significantly elevated above controls, the values decreased 9-9% from the 4-km values later in...
Hubbell JA, Muir WW, Sams RA.We determined the cardiopulmonary changes in horses given guaifenesin alone and in the same horses given xylazine (IV) immediately before administration of guaifenesin. In addition, plasma guaifenesin concentrations were determined in horses and 2 pregnant mares and compared with previously published values in ponies. The dose of guaifenesin necessary to produce lateral recumbency in adult horses was 134 +/- 34 mg/kg (mean +/- SD). The administration of guaifenesin caused insignificant (P less than 0.05) changes in heart rate, respiratory rate, right atrial pressure, pulmonary arterial pressur...
Turner RM, Casas-Dolz R, Schlingmann KL, Hameed S.To determine whether a homologue of A-kinase anchor protein 4 (AKAP4) is present and functional as an AKAP in equine spermatozoa and examine the effect of semen cooling and cryopreservation on binding of equine AKAP4 to the regulatory (RII) subunit of protein kinase-A (PK-A). Methods: Ejaculated semen collected from 2 fertile stallions, 3 bulls, and 3 humans. Methods: Identification of an equine homologue of AKAP4 was investigated via DNA sequencing. Protein was extracted from the spermatozoa of each species for immunoblot analysis to identify AKAP4 and its precursor protein, pro-AKAP4; immuno...
Martin-Flores M, Campoy L, Ludders JW, Erb HN, Gleed RD.To compare acceleromyography (AMG) with visual assessment of train-of-four (TOF) for monitoring neuromuscular blockade and detecting residual muscle paralysis in horses receiving atracurium. Methods: Prospective, controlled clinical study. Methods: Nine adult, client-owned horses weighing 577 (436, 727) kg (median, minimum, maximum) and ASA physical status I-II, admitted for surgery. Methods: An electrical nerve stimulator was used to stimulate the peroneal nerve with TOFs at 1 minute intervals. Before and after atracurium administration (0.15 mg kg(-1), IV), the number of twitches observed (T...
Gröndahl G, Johannisson A, Jensen-Waern M.The ability of equine plasma from different donors to enhance phagocytic capacity was assessed in neutrophils obtained from seven foals, aged 7-8 days (Study A), and from seven adult horses (Study B). Neutrophils were allowed to phagocytize fluorescent yeast cells opsonized with plasma from one of three donors or with pooled serum, all previously frozen (-18 degrees C) and thawed. The results were analysed by flow cytometry. In study A, fresh autologous foal serum was also used for opsonization, and in study B, heat-inactivated plasma and pooled serum were used in addition to untreated samples...
Agrawal K, Ebel JG, Altier C, Bischoff K.The leaves of Acer rubrum (red maple), especially when wilted in the fall, cause severe oxidative damage to equine erythrocytes, leading to potentially fatal methemoglobinemia and hemolytic anemia. Gallic acid and tannins from A. rubrum leaves have been implicated as the toxic compounds responsible for red maple toxicosis, but the mechanism of action and toxic principle(s) have not been elucidated to date. In order to investigate further how red maple toxicosis occurs, aqueous solutions of gallic acid, tannic acid, and ground dried A. rubrum leaves were incubated with contents of equine ileum,...
Samuel CA, Allen WR, Steven DH.Ultrastructural studies of the uterine glands at intervals during pregnancy in the mare show that secretory activity continues after formation of the placental exchange units. The nature of the glandular secretion appeared initially to be proteinaceous, but cellular debris was also present during the last third of gestation. These secretions were absorbed by the trophoblast overlying the mouths of the glands. The fate secretions and their significance for the fetus and placenta are unknown.
Yu M, Robinson NE, Wang Z, Derksen FJ.Selective muscarinic receptor antagonists were used to identify muscarinic receptor subtypes in equine trachealis strips. The M1 receptor antagonist pirenzepine (10(-7) mol/L to 3 x 10(-5) mol/L) and the M3 receptor antagonist 4-diphenylacetoxy-N-methylpiperidine (4-DAMP, 10(-9) mol/L to 3 x 10(-7) mol/L3) dose dependently inhibited the contractile responses to electrical field stimulation (EFS) and exogenous acetylcholine (ACh). Schild plots yielded a pA2 value for pirenzepine vs ACh of 6.75 +/- 0.09, which is consistent with the affinity for M2 or M3 receptors, and a pA2 value for 4-DAMP vs ...
Pagan JD, Hauss AA, Pagan EC, Simons JL, Waldridge BM.To assess the relationship between plasma and RBC fatty acid composition and incidence and severity of squamous gastric ulcers when altered by short-chain (SC) or long-chain (LC) polyunsaturated fatty acid (PUFA) supplementation. 13 fit Thoroughbred horses in training. Horses were evaluated by gastroscopy for squamous ulcer score, gastric pH, and blood fatty acid composition prior to supplementation (UNSUPP) and after 3 months of supplementation with a corn-flax oil blend of alpha-linolenic acid and linoleic acid (SC-PUFA) or a gamma-linolenic acid (GLA)-fish oil blend of GLA, eicosapentaenoic...
Walbornn SR, Felix M, Schnobrich MR, Bradecamp EA, Scoggin CF, Stefanovski D, Hinrichs K.To determine the effect of stage of estrus cycle (day after ovulation) at the time of transvaginal ultrasound-guided follicle aspiration (TVA) on parameters related to the success of in vitro equine embryo production. 14 healthy mares were used; 11 completed the study and were included for analysis. Mares underwent TVA of all follicles ≥ 5 mm diameter at each of 3 timepoints: 7 days after ovulation, 14 days after ovulation, and S-DSF (subordinate to a dominant stimulated follicle), during estrus at 24 hours after gonadotropin administration. The 3 treatments were assigned to each mare in ran...
Hanzawa K, Lear TL, Piumi F, Bailey E.Consensus DNA sequences from human, mouse and/or rat were used to design oligonucleotide primers for equine homologues of exons 16, 17 and 20-23 of potassium chloride co-transporter (SLC12A4) and exons 10, 11 and 3, 4, respectively, for two amino acid transporters (SLC7A10 and SLC7A9). DNA sequences of the PCR products showed high sequence identity to these regions. Equine BAC clones were obtained for SLC12A4 and SLC7A10 and mapped to equine chromosomes ECA3p13 and ECA10p15, respectively, by fluorescence in situ hybridization (FISH). Several single nucleotide polymorphisms (SNP) were found. Su...
Smyth GB, Young DW, Hammond LS.Gastrin is the only hormone known to stimulate secretion of hydrochloric acid. It also has trophic effects on specific parts of the mucosa of the gastrointestinal tract. Using radioimmunoassay techniques, postprandial serum gastrin and insulin concentrations were measured in six adult horses to establish effects of different diets on gastrin concentrations. Insulin concentrations were measured to provide support to the patterns of gastrin secretion because patterns of insulin secretion were already known. The horses were fed coastal bermuda hay, or twice daily 5 kg of a complete pelleted ratio...
Higgins AJ, Lees P.The presence of cyclooxygenase products of arachidonic acid metabolism in carrageenin-induced inflammatory exudate was investigated in ponies using two models. In the first model, an inflammatory response was stimulated by injecting carrageenin into subcutaneously implanted polypropylene tissue cages and exudates were collected at five predetermined times between 3 and 48 h. In the second model, exudates were harvested at 6, 12 and 24 h from carrageenin-impregnated polyester sponges which had also been inserted beneath the skin. Prostaglandin (PG) E2, thromboxane (TX) B2 and the stable breakdo...
Stomp M, Leroux M, Cellier M, Henry S, Hausberger M, Lemasson A.While the vocal coding of human and animal internal states has been widely studied, the possible acoustic expression of "positive" emotions remains poorly known. Recent studies suggest that snorts (non-vocal sounds produced by the air expiration through the nostrils) appear to be reliable indicators of positive internal states in several ungulate species. Here, we hypothesised in horses that the acoustic structure of the snort could vary with the subjects' current emotional state. Indeed, a preliminary sound analysis of snorts let us suggest structure variations related to the presence of puls...
Doherty TJ, Andrews FM, Abraha TW, Osborne D, Frazier DL.The effect of metoclopramide on gastric emptying of a liquid marker in horses was evaluated by measuring serum concentrations of acetaminophen. Gastric emptying was determined in normal, fasted horses (n = 7), horses given endotoxin intravenously (n = 7), and horses given intravenous metoclopramide plus endotoxin (n = 6). The mean time to reach maximum serum acetaminophen concentration (Tmax), the maximum serum concentration (Cmax), and the area under the serum acetaminophen concentration vs time curve (AUC) were compared among treatment groups. Endotoxin caused a profound delay in gastric emp...
Hole C, Murray R, Marlin D, Freeman P.Despite numerous studies investigating responses to visual perception, there is limited research into how horses respond to different auditory stimuli. Although 'noise-damping' ear covers are frequently used on sport horses to minimise distraction from external auditory stimuli, the effectiveness of ear covers has not been established. This study aimed to (i) investigate the responses of horses to different sounds commonly present in a competition environment, and (ii) compare these responses in the presence and absence of ear covers. A total of 18 horses were presented with 5 sounds commonly ...
Weiss DJ, Evanson OA, Green BT, Brown DR.To study the in vitro effects of cecal contents incubated with corn starch on colonic permeability in horses. Methods: 4 healthy adult ponies. Methods: Mucosal specimens were obtained from the right ventral colon and mounted in Ussing chambers. Changes in short circuit current, conductance, and large-molecule permeability in response to addition of cecal contents and cecal contents incubated with corn starch were evaluated for 120 minutes. Results: Incubation of cecal contents with corn starch for 8 hours resulted in a decrease in cecal content pH and an increase in lactic acid concentration. ...
Jones AJ, Bee JA.The digital flexor tendons of the neonate and adult horse have been compared with respect to variation in extracellular matrix composition along their length. Two pepsin-sensitive, acetic acid soluble proteins, molecular weight (Mr) 52 kD (np 52) and Mr 54 kD (np 54), were prominent throughout the length of neonatal tendons. In adult tendon, np 52 and np 54 were less abundant and restricted to the cannon (metacarpal) region. In contrast, a single pepsin- and collagenase-resistant protein of Mr 55 kD (fp 55) was exclusive to the fetlock (metacarpophalangeal joint) region regardless of age, alth...
Reyes AM, Jahr H, van Schie HT, Weinans H, Zadpoor AA.The elastic strain limit (ESL) of tendons is the point where maximum elastic modulus is reached, after which micro-damage starts. Study of damage progression in tendons under repetitive (fatigue) loading requires a priori knowledge about ESL. In this study, we propose three different approaches for predicting ESL. First, one single value is assumed to represent the ESL of all tendon specimens. Second, different extrapolation curves are used for extrapolating the initial part of the stress-strain curve. Third, a method based on comparing the shape of the initial part of the stress-strain curve ...
Journal of mass spectrometry : JMSFebruary 1, 1997
Volume 32, Issue 2 152-158 doi: 10.1002/(SICI)1096-9888(199702)32:2<152::AID-JMS456>3.0.CO;2-W
Anderson MA, Wachs T, Henion JD.A method based on ionspray liquid chromatography/tandem mass spectrometry (LC/MS/MS) was developed for the determination of reserpine in equine plasma. A comparison was made of the isolation of reserpine from plasma by liquid-liquid extraction and by solid-phase extraction. A structural analog, rescinnamine, was used as the internal standard. The reconstituted extracts were analyzed by ionspray LC/MS/MS in the selected reaction monitoring (SRM) mode. The calibration graph for reserpine extracted from equine plasma obtained using liquid-liquid extraction was linear from 10 to 5000 pg ml-1 and t...
MacLaren JA, McHorse BK.The absence of preserved soft tissues in the fossil record is frequently a hindrance for palaeontologists wishing to investigate morphological shifts in key skeletal systems, such as the limbs. Understanding the soft tissue composition of modern species can aid in understanding changes in musculoskeletal features through evolution, including those pertaining to locomotion. Establishing anatomical differences in soft tissues utilising an extant phylogenetic bracket can, in turn, assist in interpreting morphological changes in hard tissues and modelling musculoskeletal movements during evolution...
Hannant D, O'Neill T, Ostlund EN, Kydd JH, Hopkin PJ, Mumford JA.A paresis isolate of equid herpesvirus 1 (EHV1, Ab4/8) and a plaque-purified virus derived from it (EHV1, Ab4/13), induced long-term suppression of both mitogenic and antigen-specific lymphocyte proliferations in adult outbred ponies. Peripheral blood mononuclear cells (PBMC) taken from a pony after EHV1 infection suppressed the in vitro function of normal cells but serum did not. This showed that the observed immune suppression was associated with circulating PBMC and/or their products rather than circulating soluble factors such as antigen or immune complexes. The results suggested that prod...
Loganathan D, Yi R, Patel B, Zhang J, Kong N.Resolution of cathinone enantiomers in equine anti-doping analysis is becoming more important to distinguish the inadvertent ingestion of plant-based products from those of deliberate administration of designer synthetic analogs. With this in mind, a rapid and sensitive method was developed and validated for the detection, resolution and quantitative determination of cathinone enantiomers in horse blood plasma and urine. The analytes were recovered from the blood plasma and urine matrices by using a liquid-liquid extraction after adjusting the pH to 9. The recovered analytes were derivatized w...
Boscan P, Van Hoogmoed LM, Pypendop BH, Farver TB, Snyder JR.To determine the pharmacokinetics and effects of the morphine antagonist N-methylnaltrexone (MNTX) on gastrointestinal tract function in horses when administered alone and in combination with morphine. Methods: 5 healthy adult horses. Methods: Horses were treated with MNTX (1 mg/kg, IV), and serial blood samples were collected for determination of drug pharmacokinetics. For evaluation of effects on the gastrointestinal tract when administered alone, MNTX was administered at a dosage of 0.75 mg/kg, IV, twice daily for 4 days. For evaluation of effects when administered concurrently with morphin...
Epstein V.Hyperkalaemia affected the equine myocardium. The minimum plasma potassium concentration required to induce electrocardiographic changes was 6.2 mmol/litre and severe cardiotoxic effects were observed at levels of 8.0 to 10.1 mmol/litre in this experimental situation. The most consistent sign of hyperkalaemia was broadening and flattening of the P wave, which was generally associated with a change in T waves in the chest lead from negative to positive. The more pronounced the hyperkalaemia, the less pronounced the P wave and the more peaked positive the T wave. Severe hyperkalaemia was associa...
Dippel M, Zsoldos RR, Licka TF.Pressure in the atlanto-axial region due to hyperflexion ('rollkur') may influence the development of a nuchal bursa, as adventitious bursae may be caused by pressure. Investigating the pressure between the nuchal ligament and atlas/axis in a flexed position may provide information on the pathogenesis of nuchal bursitis. In this study, ten equine head and neck specimens with one side of the soft tissues over the cervical vertebral spine removed were placed in lateral recumbency on a table in neutral, mildly flexed, and hyperflexed head and neck positions. Angulations of the neck were measured ...
