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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.
Physiologic effects of nasopharyngeal administration of supplemental oxygen at various flow rates in healthy neonatal foals. To evaluate the effects of various flow rates of oxygen administered via 1 or 2 nasal cannulae on the fraction of inspired oxygen concentration (FIO2) and other arterial blood gas variables in healthy neonatal foals. Methods: 9 healthy neonatal (3- to 4-day-old) foals. Methods: In each foal, a nasal cannula was introduced into each naris and passed into the nasopharynx to the level of the medial canthus of each eye; oxygen was administered at 4 flow rates through either 1 or both cannulae (8 treatments/foal). Intratracheal FIO2, intratracheal end-tidal partial pressure of carbon dioxide, and a...
Selected ovarian ultrasonographic characteristics during vernal transition are useful to estimate time of first ovulation of the year. It is important to get mares pregnant as early as possible after vernal transition and thus, identification signs of impending 1st ovulation of the year are warranted. To identify clinical indicators of an approaching first ovulation of the year, mares were teased with a stallion for oestrous detection starting January 3 and subjected to ultrasonographic examination. Day of first appearance of uterus oedema, follicular wall invagination, intrafollicular echogenicity, double contour of the follicle wall, increase in granulosa thickness, follicular wall hyperechogenicity and appearance of pear-s...
Influence of the chemical shift artifact on measurements of compact bone thickness in equine distal limb MR images. The effect of the chemical shift artifact, resulting from misregistration or phase cancellation at the interface between compact and trabecular bone, on apparent bone thickness was quantified in six isolated equine limbs. Sagittal T1-weighted spin echo (SE) and in-phase three-dimensional spoiled gradient echo (SPGR) images were acquired twice with a 1.5 T magnetic resonance (MR) unit, switching the frequency encoding direction between acquisitions. Out-of-phase SPGR images were also obtained. MR images with different frequency encoding directions were compared with each other and to radiograph...
Length difference between equine ZFX and ZFY genes and its application for molecular sex determination. we analyzed the sex chromosome-encoding ZFX-ZFY genes and tested molecular sexing using the amplification patterns of intron 9 of ZFX-ZFY in the horse. Results: the amplification of the ZFX-ZFY produced two distinct patterns, reflecting sexual dimorphism based on a length difference between the X and Y chromosomes. The amplification products from foals showed two distinct bands: one was common to all foals and mares, indicating that this band was amplified from ZFX, while the other was specific to some foals, indicating that it was from ZFY. The result based on the PCR assay was identical to t...
Correlation of product ion profiles with molecular structures of androgenic and anabolic steroids in ESI MS/MS. Androgenic and anabolic steroids (AASs) are a class of chemical substances closely related to testosterone in molecular structure. They can be abused to enhance performances in human and equine athletes, and are banned by the sports authorities. To assist with method development for doping analyses of AASs, investigations were conducted to correlate their product ion profiles with the molecular structures. Although very similar in chemical structure, AASs generated noticeably different product ion profiles from collision-induced dissociation (CID). On the basis of both outlines of the product ...
Positive effect of FSH but not LH on early development of the dominant follicle in mares. The effects of FSH, LH or both on follicular growth and intrafollicular free insulin-like growth factor (IGF)-1 and oestradiol were investigated in mares after the beginning of deviation (largest follicle >/= 20 mm; Hour 0). A single treatment with a gonadotropin-releasing hormone antagonist (acyline) was given at Hour 3 to suppress the concentrations of FSH and LH. Five groups (n = 5 mares per group) were evaluated in the present study: (1) control; (2) acyline treated; (3) acyline + recombinant equine (re) FSH treated; (4) acyline + reLH treated; and (5) combined acyline + reFSH + reLH tr...
Administration of RRR-α-tocopherol to pregnant mares stimulates maternal IgG and IgM production in colostrum and enhances vitamin E and IgM status in foals. This study assessed the effect of a vitamin E supplement given to pregnant mares on immunoglobulins (Ig) levels in foals. In addition, the fatty acid (FA) content and composition of the mares' milk was assessed. Milk α-tocopherol concentrations were compared between pregnant Danish Warmblood mares (n = 17) given a daily oral supplement of 2500 international units (IU) RRR-α-tocopherol in the last 4 weeks of pregnancy and a group of unsupplemented mares (n = 17) receiving 170-320 IU vitamin E daily originating from the feed. Milk α-tocopherol was higher in supplemented mares (36.7, 12.4 and ...
Comparison of grass haylage digestibility and metabolic plasma profile in Icelandic and Standardbred horses. The aim of the present study was to compare digestibility and metabolic response in Icelandic and Standardbred horses fed two grass haylages harvested at different stages of maturity. Six horses of each breed were used in a 24-day change-over design. A total collection of faeces was made on days 15-17 and 22-24. Blood samples were collected on day 24 of each period and analysed for total plasma protein (TPP), plasma urea, non-esterified fatty acids, cortisol and insulin concentration. There were no differences in digestibility coefficients of crude protein, neutral detergent fibre or energy be...
Sympathetic innervation of the ileocecal junction in horses. The distribution and chemical phenotypes of sympathetic and dorsal root ganglion (DRG) neurons innervating the equine ileocecal junction (ICJ) were studied by combining retrograde tracing and immunohistochemistry. Immunoreactivity (IR) for tyrosine hydroxylase (TH), dopamine beta-hydroxylase (DBH), neuronal nitric oxide synthase (nNOS), calcitonin gene-related peptide (CGRP), substance P (SP), and neuropeptide Y (NPY) was investigated. Sympathetic neurons projecting to the ICJ were distributed within the celiac (CG), cranial mesenteric (CranMG), and caudal mesenteric (CaudMG) ganglia, as well ...
Muscle damage, hydration, electrolyte balance and vasopressin concentrations in successful and exhausted endurance horses. Arginine vasopressin (AVP) is released in response to depletion of the effective circulating blood volume. Endurance horses might develop exhaustion because loss of water and electrolytes in sweat with hypovolaemia and electrolytes abnormalities. Therefore, AVP should act in the control of volemia in these animals. This research evaluates the differences in AVP, hydration, electrolyte status and serum muscle enzymes in successful endurance horses in comparison with those eliminated from the competition because of exhaustion. Eighteen endurance horses, divided into two groups, successful (n = 1...
The effect of the 162 km endurance ride on equine peripheral blood neutrophil and lymphocyte functions. Strenuous exercise is recognized as a stress, which may induce functional immunodeficiency and increase individual susceptibility to infection. It has been shown in equine athletes, that alterations in leukocyte functions occur after moderate and submaximal exertion, however, no data deal with the effect of extreme physical exertion. In this study, we evaluated leukocyte functions (neutrophil oxidative burst and lymphocyte proliferation activity in response to mitogens) in horses following the CEI 3* 162 km endurance ride. Exercise-induced stress was manifested as neutrophilic leukocytosis and...
Direct observation of myoglobin structural dynamics from 100 picoseconds to 1 microsecond with picosecond X-ray solution scattering. Here we report structural dynamics of equine myoglobin (Mb) in response to the CO photodissociation visualized by picosecond time-resolved X-ray solution scattering. The data clearly reveal new structural dynamics that occur in the timescale of ∼360 picoseconds (ps) and ∼9 nanoseconds (ns), which have not been clearly detected in previous studies.
Preliminary study of capsule endoscopy in the small intestine of horses. 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 ...
Electrochemical study of gelatin as a matrix for the immobilization of horse heart cytochrome c. The aim of this paper is to emphasize the strength of gelatin as a stable matrix for redox enzymes. Cyclic voltammetry has been applied for a detailed electrochemical study of horse heart cytochrome c (HHC) entrapped in a gelatin matrix immobilized on a gold electrode. The influence of the HHC concentration, the mass percentage of the gelatin and the nature of the gelatin on the electrochemical behaviour of HHC have been described in detail. In addition, attenuated total reflection infrared (ATR-IR) spectroscopy was used to prove the immobilization on a qualitative and conformational level. Th...
In vitro selection and differentiation of ivermectin resistant cyathostomin larvae. Cyathostomins are considered to be the primary helminth pathogen of horses and macrocyclic lactones (ML) are the most frequently used anthelmintics. Therefore, ML resistance is a serious threat for the control of these parasites. In the present study ivermectin resistant cyathostomin L3 were in vitro selected, using a reiterative larval migration inhibition assay (rLMIA) and differentiated by reverse line blot (RLB). Larvae were obtained from two populations, one from a never treated, free-roaming horse population in the nature reserve Oostvaardersplassen (OVP) and the other from regularly ive...
Cross-sectional area of the tendons of the tarsal region in Standardbred trotter horses. The assessment of a normal range for cross-sectional area (CSA) of tendons in the tarsal region is important in order to use them as reference values in the identification of pathological changes of dimensions. Objective: To provide normal reference values for the CSA of the tendons of the tarsus of Standardbred trotter horses (STH) by means of ultrasonography. Methods: Transverse echographic images of the tendons were obtained at different levels proximodistally; these images were digitised and CSA values (mean ± s.d.) were obtained for each structure. Results: The largest structure correspo...
Definite coordination arrangement of organometallic palladium complexes accumulated on the designed interior surface of apo-ferritin. Apo-ferritin (apo-Fr) mutants are used as scaffolds to accommodate palladium (allyl) complexes. Various coordination arrangements of the Pd complexes are achieved by adjusting the positions of cysteine and histidine residues on the interior surface of the apo-Fr cage.
Redox status of equine seminal plasma reflects the pattern and magnitude of DNA damage in sperm cells. Antioxidant status of seminal plasma from 23 stallions was evaluated. We found a negative correlation between total antioxidant capacity (ABTS(•+) decolorization assay) and thiol content of seminal plasma, and sperm DNA damage (8-oxoG immunostaining, TUNEL reaction, comet assay). Low seminal redox status was the strongest correlated with 8-oxoG level which may indicate that seminal total antioxidant capacity influences mainly the formation of single strand DNA breaks in sperm cells. Since inter-individual differences in seminal antioxidant status were reported, we postulated that the redox s...
The use of intra-articular corticosteroids in the horse: what is known on a scientific basis? Intra-articular use of corticosteroids has become a recent focus (or re-focus) of attention in the Thoroughbred racing industry. This manuscript reviews the clinical use and scientific basis of intra-articular corticosteroid administration including catastrophic injury, articular cartilage degradation and the development of osteoarthritis (OA), as well as the timing of injection relative to racing.
Isolation of equine bone marrow-derived mesenchymal stem cells: a comparison between three protocols. There is a need to assess and standardise equine bone marrow (BM) mesenchymal stem cell (MSC) isolation protocols in order to permit valid comparisons between therapeutic trials at different sites. Objective: To compare 3 protocols of equine BM MSC isolation: adherence to a plastic culture dish (Classic) and 2 gradient density separation protocols (Percoll and Ficoll). Methods: BM aspirates were harvested from the sternum of 6 mares and MSCs isolated by all 3 protocols. The cell viability after isolation, MSC yield, number of MSCs attained after 14 days of culture and the functional characteri...
Assessment of the mineral density and mineral content of the equine third metacarpal and first phalanx bone by dual energy x-ray absorptiometry. In the first part of this methodological study eleven metacarpi of 9 skeletally normal horses were examined from 4 directions by dual energy x-ray absorptiometry (DXA). The differences between the dorsopalmar-palmarodorsal and lateromedial-mediolateral (opposite sites) bone mineral density (BMD) values were found to be nonsignificant. In the second part of the study the precision of the Norland XR-26 densitometer was tested by measuring 34 metacarpal bones and 34 proximal phalanges, each of them three times, from a single direction. The difference between the individual measurements of the fir...
Evaluation of cardiovascular, respiratory and biochemical effects, and anesthetic induction and recovery behavior in horses anesthetized with a 5% micellar microemulsion propofol formulation. To characterize cardiovascular, respiratory and biochemical effects and recovery behavior associated with a 3-hour continuous infusion of a micellar microemulsion propofol formulation in horses. Methods: Prospective experimental trial. Methods: Six healthy adult horses, 9 +/- 2 years old and weighing 557 +/- 14 kg. Methods: All horses received xylazine (1 mg kg(-1), IV) 5 minutes prior to anesthetic induction. Each horse was anesthetized on two occasions with a 5% micellar microemulsion propofol formulation (2 mg kg(-1), IV); first as a single bolus (phase I) and then as a 3-hour continuous in...
A weighted osteon morphotype score outperforms regional osteon percent prevalence calculations for interpreting cortical bone adaptation. Using circularly polarized light microscopy,we described a weighted-scoring method for quantifying regional distributions of six secondary osteon morphotypes(Skedros et al.: Bone 44 (2009) 392-403). This osteon morphotype score (MTS) strongly correlated with "tension" and "compression" cortices produced by habitual bending. In the present study, we hypothesized that the osteon MTS is superior to a relatively simpler method based on the percent prevalence (PP) of these osteon morphotypes. This was tested in proximal femoral diaphyses of adult chimpanzees and habitually bent bones: calcanei from...
Is FAS/Fas ligand system involved in equine corpus luteum functional regression? Proapoptotic factor Fas ligand (FASL) and its cell surface receptor FAS are tumor necrosis factor superfamily members that trigger apoptosis in different cell types. However, their influence on luteal steroidogenesis is not clearly understood. The aim of the present work was to determine (i) the presence of the cytokine FASL and its receptor FAS in the mare's corpus luteum (CL) throughout the luteal phase, as well as (ii) the influence of FASL alone, or together with the cytokines tumor necrosis factor alpha (TNF) and interferon gamma (IFNG), on equine luteal cell production of luteotrophic an...
Functional electrical stimulation of the left recurrent laryngeal nerve using a vagus nerve stimulator in a normal horse. The aim of this study was to assess the feasibility of implanting an existing vagus nerve stimulating (VNS) electrode around the recurrent laryngeal nerve. The stimulus response characteristics required to achieve abduction of the ipsilateral arytenoid by the VNS electrode in the normal horse could then be determined. The electrode was wound around the left recurrent laryngeal nerve at the cervical level and connected to a pulse generator. Stimulus response characteristics were obtained by measuring stimulated arytenoid displacement endoscopically in the standing, non-sedated horse. A full and...
Comparison of three methods of DNA extraction from peripheral blood mononuclear cells and lung fragments of equines. We compared three different protocols for DNA extraction from horse peripheral blood mononuclear cells (PBMC) and lung fragments, determining average final DNA concentration, purity, percentage of PCR amplification using beta-actin, and cost. Thirty-four samples from PBMC, and 33 samples from lung fragments were submitted to DNA extraction by three different protocols. Protocol A consisted of a phenol-chloroform and isoamylic alcohol extraction, Protocol B used alkaline extraction with NaOH, and Protocol C used the DNAzol((R)) reagent kit. Protocol A was the best option for DNA extraction from...
Comparison of in vitro digestibility estimates using the DaisyII incubator with in vivo digestibility estimates in horses. The objective of this study was to determine if in vitro methodologies developed for the Ankom Daisy(II) incubator could produce accurate estimates of in vivo equine DM digestibility (DMD) and NDF digestibility (NDFD) when equine feces were used as the inoculum source. Four mature geldings were utilized in a 4 × 4 Latin square design experiment with a 2 × 2 factorial arrangement of dietary treatments (timothy hay, alfalfa hay, timothy hay plus oats, and alfalfa hay plus oats), in which the geldings were individually housed and fed. During each 5-d total fecal collection period, feces were co...
Evaluation of genes involved in prostaglandin action in equine endometrium during estrous cycle and early pregnancy. The aim was to evaluate expression of genes involved in the biosynthesis of prostaglandins (PTG), Prostaglandin H Synthase-1 (PTGS1) and PTGS2, PGF synthase (PTGFS), and PGE synthase (PTGES), PGF receptor (PTGFR), PGE receptors (PTGER2 and PTGER4), prostaglandin transporter (SLCO2A1) and hydroxyprostaglandin dehydrogenase-15 (HPGD). Endometrial biopsies were obtained from mares on day of ovulation (d0, n=4), late diestrus (LD, n=4), early luteolysis (EL, n=4) and after luteolysis (AL, n=4) during the cycle. Stages of the cycle were confirmed by plasma progesterone concentrations measured daily...
Supporting limb laminitis. Supporting limb laminitis poses a threat to all horses suffering from severe unilateral lameness. Despite its devastating effects, relatively little is known about the precise pathologic processes that lead to its development. This article reviews the potential mechanisms of supporting limb laminitis, and the authors present some preliminary data based on advanced imaging and computer-based modeling techniques aimed at further elucidating the etiology of this unique form of laminitis. Gaining a better understanding of the pathologic processes that lead to supporting limb laminitis is essential...
