Omneity® Pellets
All-In-One Vitamin & Mineral Pellet
Topic:Physiology
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.
Comparison of alfaxalone, ketamine and thiopental for anaesthetic induction and recovery in Thoroughbred horses premedicated with medetomidine and midazolam. There is limited information on clinical use of the new injectable anaesthetic agent alfaxalone in Thoroughbred horses. Objective: To compare anaesthetic induction and recovery characteristics and cardiopulmonary responses between alfaxalone, ketamine and thiopental in Thoroughbred horses premedicated with medetomidine and midazolam. Methods: Randomised blinded experimental cross-over study. Methods: Six Thoroughbred horses were anaesthetised 3 times with alfaxalone 1 mg/kg bwt, ketamine 2.5 mg/kg bwt or thiopental 4 mg/kg bwt after premedication with medetomidine 6 μg/kg bwt and midazola...
Cardiovascular, respiratory and metabolic responses to apnea induced by atlanto-occipital intrathecal lidocaine injection in anesthetized horses. To determine physiologic responses to apnea-induced severe hypoxemia in anesthetized horses. Methods: Prospective experimental study. Methods: Six university-owned horses with a median (range) body weight of 500 (220-510) kg and aged 13.5 (0.8-24.0) years scheduled for euthanasia. Methods: Xylazine-midazolam-ketamine-anesthetized horses breathing room air spontaneously were instrumented with a facial artery catheter for pressure measurement and blood sampling, and were made apneic with atlanto-occipital intrathecal lidocaine (4 mg kg ). Cardiopulmonary, biochemical and hematologic variable...
Management of the pregnant mare and long-term consequences on the offspring. The study of early developmental conditioning of health and disease in adulthood is particularly relevant in the horse, which is bred mainly to perform in demanding sport challenges. On the basis of this concept, the management of the broodmare could be considered an effective means to produce animals with the desired features. Knowledge on the Developmental Origins of Health and Disease in the equine species remains relatively scarce, with some experimental studies and one single epidemiologic study. Data highlight the determinant role of the maternal environment for postnatal body conformati...
Effects of erythropoietin on systemic hematocrit and oxygen transport in the splenectomized horse. To test the hypotheses that erythropoietin (rhuEPO) treatment increases systemic hematocrit, maximal O2 uptake (VO2max, by elevated perfusive and diffusive O2 conductances) and performance five female horses (4-13 years) received 15 IU/kg rhuEPO (erythropoietin) three times per week for three weeks. These horses had been splenectomized over 1 year previously to avoid confounding effects from the mobilization of splenic red blood cell reserves. Each horse performed three maximal exercise tests (one per month) on an inclined (4°) treadmill to the limit of tolerance; two control trials and one f...
Anatomical heterogeneity of tendon: Fascicular and interfascicular tendon compartments have distinct proteomic composition. Tendon is a simple aligned fibre composite, consisting of collagen-rich fascicles surrounded by a softer interfascicular matrix (IFM). The composition and interactions between these material phases are fundamental in ensuring tissue mechanics meet functional requirements. However the IFM is poorly defined, therefore tendon structure-function relationships are incompletely understood. We hypothesised that the IFM has a more complex proteome, with faster turnover than the fascicular matrix (FM). Using laser-capture microdissection and mass spectrometry, we demonstrate that the IFM contains more ...
Circadian rhythm of calciotropic hormones, serum calcium, phosphorus and magnesium during the shortest and longest days of the year in horses in New Zealand. A study was conducted to determine the circadian rhythms and trends of vitamin D metabolites including 25-hydroxyvitamin D3 , 25-hydroxyvitamin D2 , 1,25-dihydroxyvitamin D and parathyroid hormone, in addition to serum calcium, phosphorus and magnesium concentrations in horses over 48 h on the shortest and longest days of the year in 2013. Five healthy adult horses (Equus caballus) were on a constant pasture feeding regimen, and blood samples were collected from each horse every 3 h over a 48-h period, starting at 07:00 PM on day one and finishing at 07:00 PM on day three, for the measurem...
Extracellular calcium regulates protein tyrosine phosphorylation through calcium-sensing receptor (CaSR) in stallion sperm. Protein tyrosine phosphorylation (PY), a hallmark of sperm capacitation, is inhibited by extracellular calcium in stallion sperm. The objective of this study was to determine the presence and influence of the calcium-sensing receptor (CaSR) in this phenomenon. First, the presence of the CaSR was demonstrated in stallion sperm. We then tested its function in these gametes using its inhibitor NPS2143 or its agonist AC34356. Sperm were capacitated for 4 hr in modified Whitten's medium with 25 mM bicarbonate plus NPS2143 and 2.4 mM calcium or AC34356 alone, followed by analysis of PY. Inhibi...
Different effects of an extended photoperiod treatment on growth, gonadal function, and condition of hair coats in Thoroughbred yearlings reared under different climate conditions. One- to two-year-old Thoroughbred colts and fillies being reared in Miyazaki (warm climate) and Hidaka (cold climate), Japan, were administered extended photoperiod (EP) treatment between December 20 and the following April 10, and its effect on growth, endocrine changes, gonadal activation, and hair coat condition was investigated. In colts reared in Miyazaki, no effect of EP treatment was noted on the growth indices, including body weight (BW), height at withers (HW), girth, and cannon circumference (CC), whereas the BWs and CCs of fillies were significantly higher in the EP treatment group ...
Promoting effects of an extended photoperiod treatment on the condition of hair coats and gonadal function in Thoroughbred weanlings. The effects of an extended photoperiod (EP) treatment (14.5 hr light, 9.5 hr dark) on Thoroughbred colts and fillies from December 25 at 7-9 months old to the following May at 12-14 months old on coat condition and gonadal functions were investigated. Coat condition was evaluated in April. The colts and fillies in the EP treatment group changed from winter to summer coats (molting of winter coats), whereas those in the control group did not. To determine the day of first ovulation, the plasma concentrations of progesterone were measured once a month in fillies. The day of first ovulation was a...
Seasonal changes in serum progesterone levels in Thoroughbred racehorses in training. The objective of the present study was to verify the seasonal luteal activity of racehorses in training in Japan from March to August. We allocated 102 horses into a luteal activity group and non-luteal activity group. The luteal activity group included horses with serum progesterone levels that were consistently >1 ng/ml and changed by ± 1 ng/ml. In contrast, the progesterone levels of the non-luteal activity group were consistently <1 ng/ml. In late spring (from May 1 to June 30) and summer (from July 1 to August 31), the percentage of horses in the luteal activity group was significa...
Determination of amino acid profile of mare milk produced in the highlands of the Kyrgyz Republic during the milking season. This study was carried out to determine the influence of milking season on amino acid (AA) profile and chemical composition of milk samples from Kyrgyz native breed mares under traditional pasture conditions. Milk samples were collected monthly from May to August 2014 from mares grazing at 2,200 m above sea level. The AA composition was determined by precolumn derivatization with diethyl ethoxymethylenemalonate in HPLC and 18 AA were determined in mare milk. The analytical parameters of linearity (0.01-4 μg/mL), precision of the method (0.26-4.88% relative standard deviation), derivatization ...
A study of the distribution of color Doppler flows in the superficial digital flexor tendon of young Thoroughbreds during their training periods. Aim of this study was to evaluate the relationships of exercise and tendon injury with Doppler flows appearing in the superficial digital flexor tendon (SDFT) of young Thoroughbreds during training periods. The forelimb SDFTs of 24 one- to two-year-old Thoroughbreds clinically free of any orthopaedic disorders were evaluated using grey-scale (GS) and color Doppler (CD) images during two training periods between December 2013 to April 2015. Twelve horses per year were examined in December, February, and April in training periods that began in September and ended in April. The SDFT was evaluated...
Palisade Endings Are a Constant Feature in the Extraocular Muscles of Frontal-Eyed, But Not Lateral-Eyed, Animals. To test whether palisade endings are a general feature of mammalian extraocular muscles (EOMs). Methods: Thirteen species, some frontal-eyed (human, monkey, cat, and ferret), and others lateral-eyed (pig, sheep, calf, horse, rabbit, rat, mouse, gerbil, and guinea pig) were analyzed. Palisade endings were labeled by using different combinations of immunofluorescence techniques. Three-dimensional reconstructions of immunolabeled palisade endings were done. Results: In all frontal-eyed species, palisade endings were a consistent feature in the rectus EOMs. Their total number was high and they exh...
Motor ability of forelimb both on- and off-riding during walk and trot cadence of horse. The aim of this study was to investigate the motor ability of forelimb according to on- or off-riding during cadences (walk and trot) of horse. Horses and rider selected as subject consisted of total 37 heads of Jeju native horse and 1 female rider. The variables analyzed composed of 1 stride length, 1 step length, elapsed time of stance, elapsed time of swing, elapsed time of 1 step, and forward velocity (x-axis). Two-way analysis of variance of variables was employed for the statistical analysis with the level of significance set at 5% (P<0.05). Trot cadence showed significant difference ...
Seasonal thyroid and lipid profiles in Thoroughbred pregnant and nonpregnant mares (Equus caballus). The purpose of this study was to determine which physiological seasonal thyroid and lipid panel (triglyceride, [TG], total cholesterol, [tCho], high-density lipoprotein cholesterol, [HDL Cho], LDL cholesterol, phospholipids, [PDs]) changes occur in 12 Thoroughbred pregnant and six nonpregnant mares over a period of 12 months, from April to March, by into account the lactation stage. Serum total triiodothyronine (T3) and thyroxine (T4) levels were measured using immunoenzymatic assay kits; the serum lipid panel was analyzed using the enzymatic colorimetric method. One-way ANOVA reported a sign...
The dynamic steroid landscape of equine pregnancy mapped by mass spectrometry. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) allowed comprehensive analysis of various steroids detectable in plasma throughout equine gestation. Mares (n=9) were bled serially until they foaled. Certain steroids dominated the profile at different stages of gestation, clearly defining key physiological and developmental transitions. The period (weeks 6-20) coincident with equine chorionic gonadotropic (eCG) stimulation of primary corpora lutea and subsequent formation of secondary luteal structures was defined by increased progesterone, 17OH-progesterone and androstenedione, all ...
Topography and ultrasonographic identification of the equine pulmonary vein draining pattern. Information on ultrasound examination of equine pulmonary veins is scarce due to a lack of in-depth anatomical information. Each pulmonary vein drains a specific lung lobe region, after which those veins merge into a collecting antrum, before opening into the left atrium through their respective ostia. The aim of this study was, by using anatomical dissection and silicone casting of equine cardiopulmonary sets, to study the venous drainage of both lungs and the position of the ostia and to investigate whether the ostia can be identified and differentiated using ultrasound. Three out of the fou...
Changes in intrafollicular concentrations of free IGF-1, activin A, inhibin A, VEGF, estradiol, and prolactin before ovulation in mares. Changes in intrafollicular growth factors and hormones were evaluated in vivo in postdeviation and impending ovulation follicles. Mares (n = 30) were randomly assigned to five experimental groups based on target diameters of 25, 30, 35, 40 mm, and impending signs of ovulation. Furthermore, data belonging to two or more proximal diameter groups that were not different were combined and regrouped for each factor separately. Follicular fluid-free insulin-like growth factor 1 was highest (P 0.05) among groups. Additionally, follicular fluid activin A tended (P < 0.06) to be higher in i...
Feasibility and Safety of Contrast-Enhanced Ultrasound in the Distal Limb of Six Horses. Vascular alterations play important roles in many orthopedic diseases such as osteoarthritis, tendonitis, and synovitis in both human and equine athletes. Understanding these alterations could enhance diagnosis, prognosis, and treatment. Contrast-enhanced ultrasound (CEUS) could be a valuable method for evaluation of blood flow and perfusion of these processes in the equine distal limb, however no reports were found describing feasibility or safety of the technique. The goal of this prospective, experimental study was to describe the feasibility and safety of distal limb CEUS in a sample of si...
The effect of isosorbide dinitrate on uterine and ovarian blood flow in cycling and early pregnant mares: A pilot study. Poor uterine perfusion has been proposed as a cause of infertility in mares. The objective of this study was to investigate the effect of isosorbide dinitrate (ISDN), a nitric oxide donor, on uterine and ovarian blood flow resistance during diestrus and early pregnancy in mares. Six Trotter mares, aged 7 to 14 years, were examined daily during the first 11 days of three diestrous periods, and five of those mares were also examined during the first 11 days of two pregnancies. Six mares randomly received a placebo, a low dose (30 mg, ISDN30), or a high dose of ISDN (60 mg, ISDN60) through t...
Regional heterogeneity in the reactivity of equine small pulmonary blood vessels. Regional differences in large equine pulmonary artery reactivity exist. It is not known if this heterogeneity extends into small vessels. The hypothesis that there is regional heterogeneity in small pulmonary artery and vein reactivity to sympathomimetics (phenylephrine and isoproterenol) and a parasympathomimetic (methacholine) was tested using wire myography on small vessels from caudodorsal (CD) and cranioventral (CV) lung of 12 horses [9 mares, 3 geldings, 8.67 ± 0.81 (age ± SE) yr, of various breeds that had never raced]. To study relaxation, vessels were precontracted with U46619 (10(-...
[Reference ranges of insulin, insulin like growth factor-1 and adrenocorticotropic hormone in ponies]. The aim of this study was to validate a chemiluminescence immunometric assay using the IMMULITE 2000® for the determination of adrenocorticotropic hormone (ACTH), insulin and insulin-like growth factor-1 (IGF-1) from which reference ranges were calculated for ponies. Methods: Blood samples of 130 ponies aged 3-32 years were collected in the afternoon. The reference ranges were calculated according to the Guideline EP28-A3C of the International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) from 2010. Results: The determined intraday precision for insulin was 3.28%, for ACTH 3...
The Impact of Sperm Metabolism during In Vitro Storage: The Stallion as a Model. In vitro sperm storage is a necessary part of many artificial insemination or in vitro fertilization regimes for many species, including the human and the horse. In many situations spermatozoa are chilled to temperatures between 4 and 10°C for the purpose of restricting the metabolic rate during storage, in turn, reducing the depletion of ATP and the production of detrimental by-products such as reactive oxygen species (ROS). Another result of lowering the temperature is that spermatozoa may be "cold shocked" due to lipid membrane phase separation, resulting in reduced fertility. To overcome ...
Initial analytic quality assessment and method comparison of an immunoassay for adrenocorticotropic hormone measurement in equine samples. Equine pituitary pars intermedia dysfunction (PPID) may be diagnosed by measuring baseline plasma adrenocorticotrophic hormone (ACTH). The Immulite 1000 analyzer uses an automated chemiluminescence enzyme assay, previously validated for measuring equine ACTH. Recently, an automated bench-top immunoassay analyzer (AIA-360), designed for analytes in people, became available for veterinary use. Objective: Objectives were to evaluate analytic performance of the AIA immunoassay for measuring equine ACTH, and compare the results with those obtained by the Immulite. Methods: Adrenocorticotrophic horm...
Combined albumin and bicarbonate induces head-to-head sperm agglutination which physically prevents equine sperm-oviduct binding. In many species, sperm binding to oviduct epithelium is believed to be an essential step in generating a highly fertile capacitated sperm population primed for fertilization. In several mammalian species, this interaction is based on carbohydrate-lectin recognition. D-galactose has previously been characterized as a key molecule that facilitates sperm-oviduct binding in the horse. We used oviduct explant and oviduct apical plasma membrane (APM) assays to investigate the effects of various carbohydrates; glycosaminoglycans; lectins; S-S reductants; and the capacitating factors albumin, Ca(2+) a...
Equine grass sickness, but not botulism, causes autonomic and enteric neurodegeneration and increases soluble N-ethylmaleimide-sensitive factor attachment receptor protein expression within neuronal perikarya. Equine grass sickness (EGS) is of unknown aetiology. Despite some evidence suggesting that it represents a toxico-infection with Clostridium botulinum types C and/or D, the effect of EGS on the functional targets of botulinum neurotoxins, namely the soluble N-ethylmaleimide-sensitive factor attachment receptor (SNARE) proteins, is unknown. Further, while it is commonly stated that, unlike EGS, equine botulism is not associated with autonomic and enteric neurodegeneration, this has not been definitively assessed. Objective: To determine: 1) whether botulism causes autonomic and enteric neurodeg...
Effect of repeated through-and-through joint lavage on serum amyloid A in synovial fluid from healthy horses. The objective of this study was to evaluate the effect of through-and-through joint lavage on systemic and synovial serum amyloid A (SAA), total protein, nucleated cell count and percentage of neutrophils in the synovial fluid of six healthy horses. A prospective experimental study was performed where one healthy tarsocrural joint of each horse was randomly assigned to receive repeated through-and-through joint lavage at 0, 48 and 96 h. Synovial fluid and blood samples were collected at 0 (baseline), 24, 48, 72, 96 and 120 h. Systemic and synovial SAA, total protein, nucleated cell count a...
P2Y(1) receptors mediate purinergic relaxation in the equine pelvic flexure. In the equine large intestine, the knowledge of the basic mechanisms underlying motility function is crucial to properly treat motility disorders. P2Y1 receptors are responsible for mediating purinergic colonic relaxation in several species. In vitro experimental studies of the circular muscle from the equine pelvic flexure (n = 6) were performed to characterize inhibitory and excitatory neuromuscular transmission. Electrophysiological studies showed that electrical field stimulation (EFS) evoked biphasic inhibitory junction potentials (IJPs) in smooth muscle cells: a fast IJP (IJPf) follo...
High-throughput analysis of horse sperms’ 3D swimming patterns using computational on-chip imaging. Using a high-throughput optical tracking technique that is based on partially-coherent digital in-line holography, here we report a detailed analysis of the statistical behavior of horse sperms' three-dimensional (3D) swimming dynamics. This dual-color and dual-angle lensfree imaging platform enables us to track individual 3D trajectories of ∼1000 horse sperms at sub-micron level within a sample volume of ∼9μL at a frame rate of 143 frames per second (FPS) and collect thousands of sperm trajectories within a few hours for statistical analysis of their 3D dynamics. Using this high-throughp...
Aptamer based peptide enrichment for quantitative analysis of gonadotropin-releasing hormone by LC-MS/MS. Over recent years threats to racing have expanded to include naturally occurring biological molecules, such as peptides and proteins, and their synthetic analogues. Traditionally, antibodies have been used to enable detection of these compounds as they allow purification and concentration of the analyte of interest. The rapid expansion of peptide-based therapeutics necessitates a similarly rapid development of suitable antibodies or other means of enrichment. Potential alternative enrichment strategies include the use of aptamers, which offer the significant advantage of chemical synthesis onc...
