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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.
Meta-analysis evaluating resting laryngeal endoscopy as a diagnostic tool for recurrent laryngeal neuropathy in the equine athlete. Resting endoscopy has commonly been used as a method to predict laryngeal function at exercise. Objective: To perform a meta-analysis to determine the sensitivity and specificity of resting laryngeal endoscopy to predict clinical recurrent laryngeal neuropathy at exercise. Methods: Meta-analysis. Methods: Manuscripts were included if data were available for both resting and exercising airway function on all or a subset of horses. Normal resting endoscopy was defined as laryngeal grades 1 or 2 on a 4-/7-point scale or 1, 2 or 3 on a 5-point scale and normal dynamic endoscopy as a dynamic laryng...
Assessing gastrointestinal motility in healthy horses comparing auscultation, ultrasonography and an acoustic gastrointestinal surveillance biosensor: a randomised, blinded, controlled crossover proof of principle study. Auscultation and ultrasonography are noninvasive techniques used to assess gastrointestinal motility in horses. Recently, noninvasive acoustic gastrointestinal surveillance (AGIS) biosensors evaluating intestinal motility have been validated in humans. Objective: To compare AGIS to auscultation and ultrasonography for detecting decreased motility after xylazine administration. Methods: Randomised, blinded, controlled cross-over proof of principle study. Methods: Six healthy horses were evaluated under fasted and nonfasted conditions and randomly assigned to receive treatment with 0.4 mg/kg xyl...
Plasminogen activator inhibitor-1 and tenascin-C secreted by equine mesenchymal stromal cells stimulate dermal fibroblast migration in vitro and contribute to wound healing in vivo. Impaired cutaneous wound healing is common in humans, and treatments are often ineffective. Based on the significant emotional and economic burden of impaired wound healing, innovative therapies are needed. The potential of mesenchymal stromal cell (MSC)-secreted factors to treat cutaneous wounds is an active area of research that is in need of refinement before effective clinical trials can be initiated. The aims of the present study were to (i) study which MSC-secreted factors stimulate dermal fibroblast (DF) migration in vitro and (ii) evaluate the potential of these factors to promote woun...
Characterization of trotter horses urine metabolome by means of proton nuclear magnetic resonance spectroscopy. Metabolomics has been recognized as a powerful approach for disease screening. In order to highlight potential health issues in subjects, a key factor is the possibility to compare quantitatively the metabolome of their biofluids with reference values from healthy individuals. Such efforts towards the systematic characterization of the metabolome of biofluids in perfect health conditions, far from concluded for humans, have barely begun on horses. The present work attempts, for the first time, to give reference quantitative values for the molecules mostly represented in the urine metabolome of...
Intrafollicular level of steroid hormones and the expression of androgen receptor in the equine ovary at puberty. Steroidogenic activity in the equine ovary from birth to puberty has been poorly investigated. This study aimed to examine the capability of the ovarian follicles of prepubertal and pubertal fillies to produce steroid hormones and to evaluate the expression and cellular localization of androgen receptor (AR) in their ovaries. The ovaries of 6-18 month-old fillies were divided into two groups: prepubertal (PrP) - without preovulatory follicle (pF) and corpus luteum (CL), and ovulating/postpubertal (Ov/pB) - with pF and/or CL in at least one of the gonads. Adult mares (Me) were used as a control...
Anticipatory response before competition in Standardbred racehorses. It is generally accepted that besides cortisol concentrations, parameters of heart rate variability (HRV) are appropriate indicators of stress in horses. The aim of this study was to determine anticipatory stress in eight Standardbred stallions participating in harness race. Cortisol and HRV responses to a mild exercise performed in training circumstances were compared to a maximal effort exercise performed in real trotting race conditions. Parameters of HRV reflecting vagal (root mean square of the successive differences, RMSSD) and sympathetic nervous system activity (ratio of the low and hi...
Electromyographic changes in hind limbs of Thoroughbreds with fatigue induced by treadmill exercise. OBJECTIVE To quantify fatigue-induced electromyographic changes in hind limb muscles in horses. ANIMALS 8 Thoroughbreds. PROCEDURES The left and right hind limb longissimus dorsi, tensor fasciae latae, gluteus medius, and biceps femoris muscles were instrumented for surface electromyography. Hoof strain gauges were attached to confirm stride cycle. Each horse was galloped on a treadmill (grade, 3%) at a constant speed (12.6 to 14.7 m/s) to achieve fatigue after approximately 360 seconds. Before and after this exercise, the horses were trotted at 3.5 m/s. At 30-second intervals during galloping...
Characterization of the fecal microbiota of healthy horses. OBJECTIVE To characterize the fecal microbiota of horses and to investigate alterations in that microbiota on the basis of sample collection site (rectum vs stall floor), sample location within the fecal ball (center vs surface), and duration of environmental exposure (collection time). ANIMALS 6 healthy adult mixed-breed mares. PROCEDURES From each horse, feces were collected from the rectum and placed on a straw-bedded stall floor. A fecal ball was selected for analysis immediately after removal from the rectum and at 0 (immediately), 2, 6, 12, and 24 hours after placement on the stall floor...
Freezing of Stallion Semen: In Vitro Evaluation of Motility and Acrosin Activity in Sperm Cells Cryopreserved Using Different Semen Extenders. The work described here aimed to verify the efficiency of different extenders for cryopreservation of equine semen using sperm motility and acrosin activity as spermatic parameters. The semen was fractioned into two equal parts and resuspended in an 11% lactose solution in a 1:1 proportion, where it remained for 20 minutes at room temperature. The semen was centrifuged at 600 g for 10 minutes, and after the second centrifugation, each pellet received the freezing extender (Merck or Zorlesco) and was loaded into 4 mL straws. Each straw was placed in liquid nitrogen vapor steam for 15 minutes ...
In vivo antral follicle wall biopsy: a new research technique to study ovarian function at the cellular and molecular levels. In vivo studies involving molecular markers of the follicle wall associated with follicular fluid (FF) milieu are crucial for a better understanding of follicle dynamics. The inability to obtain in vivo samples of antral follicle wall (granulosa and theca cells) without jeopardizing ovarian function has restricted advancement in knowledge of folliculogenesis in several species. The purpose of this study in mares was to develop and validate a novel, minimally invasive in vivo technique for simultaneous collection of follicle wall biopsy (FWB) and FF samples, and repeated collection from the sam...
Horse Y chromosome assembly displays unique evolutionary features and putative stallion fertility genes. Dynamic evolutionary processes and complex structure make the Y chromosome among the most diverse and least understood regions in mammalian genomes. Here, we present an annotated assembly of the male specific region of the horse Y chromosome (eMSY), representing the first comprehensive Y assembly in odd-toed ungulates. The eMSY comprises single-copy, equine specific multi-copy, PAR transposed, and novel ampliconic sequence classes. The eMSY gene density approaches that of autosomes with the highest number of retained X-Y gametologs recorded in eutherians, in addition to novel Y-born and transp...
Composition, structure and tensile biomechanical properties of equine articular cartilage during growth and maturation. Articular cartilage undergoes structural and biochemical changes during maturation, but the knowledge on how these changes relate to articular cartilage function at different stages of maturation is lacking. Equine articular cartilage samples of four different maturation levels (newborn, 5-month-old, 11-month-old and adult) were collected (N = 25). Biomechanical tensile testing, Fourier transform infrared microspectroscopy (FTIR-MS) and polarized light microscopy were used to study the tensile, biochemical and structural properties of articular cartilage, respectively. The tensile modulus ...
Leukocyte telomere length in the Thoroughbred racehorse. Thoroughbred racehorses possess superior cardiorespiratory fitness levels and are at the pinnacle of athletic performance compared to other breeds of horses. Although equine athletes have undergone years of artificial selection for racing performance, musculoskeletal injuries and illnesses are common and concerns relating to animal welfare have been proposed. Leukocyte telomere length is indicative of biological age, and accelerated telomere shortening occurs with excess physical and psychological stress. This study was designed to explore the association between leukocyte telomere length, bio...
Stem Cell Therapy for Tendon Regeneration: Current Status and Future Directions. In adults the healing tendon generates fibrovascular scar tissue and recovers never histologically, mechanically, and functionally which leads to chronic and to degenerative diseases. In this review, the processes and mechanisms of tendon development and fetal regeneration in comparison to adult defect repair and degeneration are discussed in relation to regenerative therapeutic options. We focused on the application of stem cells, growth factors, transcription factors, and gene therapy in tendon injury therapies in order to intervene the scarring process and to induce functional regeneration ...
Early colonisation and temporal dynamics of the gut microbial ecosystem in Standardbred foals. Even if horses strictly depend on the gut microbiota for energy homeostasis, only a few molecular studies have focused on its characterisation and none on the perinatal gut microbial colonisation process. Objective: To explore the perinatal colonisation process of the foal gut microbial ecosystem and the temporal dynamics of the ecosystem assembly during the first days of life. Methods: Longitudinal study. Methods: Thirteen Standardbred mare-foal pairs were included in the study. For each pair, at delivery we collected the mare amniotic fluid, faeces and colostrum, and the foal meconium. Milk ...
TGF-β1 upregulates the expression of hyaluronan synthase 2 and hyaluronan synthesis in culture models of equine articular chondrocytes. We investigated the effect of transforming growth factor beta 1 (TGF-β1) on equine hyaluronan synthase 2 () gene expression and hyaluronan (HA) synthesis in culture models of articular chondrocytes. Equine chondrocytes were treated with TGF-β1 at different concentrations and times in monolayer cultures. In three-dimensional cultures, chondrocyte-seeded gelatin scaffolds were cultured in chondrogenic media containing 10 ng/mL of TGF-β1. The amounts of HA in conditioned media and in scaffolds were determined by enzyme-linked immunosorbent assays. mRNA expression was analyzed by semi-quantita...
Transcriptomic hallmarks of bone remodelling revealed by RNA-Seq profiling in blood of Arabian horses during racing training regime. The impact of exercises on young developing organisms is still of interest to researchers. Similarly like Thoroughbreds, Arabian horses competing at the race track. The high percent of lameness and loss of days in training are often the result of weakness in the condition of the musculoskeletal system. The objective of the presented study was to identify by RNA-Seq method, the possible skeletal system originating transcriptomic profile in peripheral blood of Arabian horses undergoing race training. Obtained results showed that one of the most significantly deregulated pathway involved in bone ...
Effects of ascorbic acid 2-glucoside and alpha-tocopherol on the characteristics of equine spermatozoa stored at 5°C. The aim of this experiment was to evaluate the effects of adding ascorbic acid 2-glucoside (AA2G), a water-soluble antioxidant and stable derivative of ascorbate, to the semen extender and compare it to the addition of vitamin C (Vit. C) and the fat-soluble antioxidant α-tocopherol (α-Toh), both individually and in combination, on the seminal variables of equine sperm submitted to cooling for 72 h. We used two ejaculates from 10 stallions and evaluated them for motility, membrane integrity, chromatin fragmentation, mitochondrial activity and lipid peroxidation. In the analysis of lipid pero...
Circannual variability in adrenocorticotropic hormone responses to administration of thyrotropin-releasing hormone in clinically normal horses in Australia. Thyrotropin releasing hormone (TRH)-stimulation testing for pituitary pars intermedia dysfunction (PPID) in horses is only recommended at certain times of the year. Current diagnostic cut-off values reflect testing in the northern hemisphere during this time. The aims of this study were to evaluate TRH stimulation testing during two different phases of the circannual pituitary cycle and to determine whether diagnostic cut-off values developed in the northern hemisphere are appropriate in Australia. Thirteen clinically normal horses at Perth, Western Australia, and 23 horses at Townsville, Quee...
Influence of cycle stage, age and endometrial biopsy score on oxytocin receptor distribution and gene expression in the cervix and uterus of non-pregnant mares. Persistent breeding-induced endometritis (PBIE) or delayed uterine clearance (DUC) are major causes of mare subfertility. Oxytocin and its receptor are thought to play significant roles in the pathogenesis of DUC but the specific roles of oxytocin receptor (OR) distribution and gene expression remain undefined. In this study both OR distribution and gene expression in the endometrium, myometrium and cervix during both luteal and non-luteal phases in non-pregnant mares (n = 27) of differing age (young: 2-9 years, n = 17; old: > 10 years, n = 10) and endometrial biopsy score were ...
Evaluation of age-dependent changes of myocardial velocity using pulsed wave and colour tissue Doppler imaging in adult warmblood horses. Our aim was to evaluate the influence of the ageing process on the myocardium using pulsed wave tissue Doppler (PW-TDI) and colour tissue Doppler imaging (cTDI) to measure myocardial velocities at three different myocardial regions (right ventricular free wall: RVFW, interventricular septum: IVS, left ventricular free wall: LVFW). A total of 60 healthy warmblood horses, aged from 3 to 30 years, were examined. The horses were divided into five age groups (group 1: 3-8 years, n = 14; group 2: 9-13 years, n = 9; group 3: 14-18 years, n = 10; group 4: 19-23 years, n = 14; group 5: 24-...
Impact of Trendelenburg (head down) and reverse Trendelenburg (head up) position on respiratory and cardiovascular function in anaesthetized horses. To describe the cardiorespiratory effects of a change in table position in anaesthetized horses. Methods: Prospective, crossover, randomized, experimental study. Methods: Six adult horses (mean body weight 621 ± 59 kg, aged 13 ± 4 years). Methods: The horses were anaesthetized twice in dorsal recumbency. They were either placed in the Trendelenburg position (head down; HD) followed by reverse Trendelenburg position (head up; HU) or in reverse order. Every position was maintained for 90 minutes. The order of positions was randomly assigned at initial anaesthesia. Extensive cardiorespiratory m...
Could the Visual Differential Attention Be a Referential Gesture? A Study on Horses (Equus caballus) on the Impossible Task Paradigm. In order to explore the decision-making processes of horses, we designed an impossible task paradigm aimed at causing an expectancy violation in horses. Our goals were to verify whether this paradigm is effective in horses by analyzing their motivation in trying to solve the task and the mode of the potential helping request in such a context. In the first experiment, 30 horses were subjected to three consecutive conditions: no food condition where two persons were positioned at either side of a table in front of the stall, solvable condition when a researcher placed a reachable reward on the ...
Lower Airway Disease in the Athletic Horse. The airways are the first part of the pathway in the oxygen transport chain that is critical to excellent athletic performance, and the lower airways are considered the final gatekeeper before oxygen enters the blood and carbon dioxide exits. Horses are blessed with large airways and lungs that allow them to be superb athletes, but the down side of this largesse on the part of evolution is that unless they are truly elite athletes they may withstand noninfectious disease of the lower respiratory tract for months to years before the owner or trainer notices. The two conditions of the lower resp...
Differences in third metacarpal trabecular microarchitecture between the parasagittal groove and condyle at birth and in adult racehorses. The aetiology of equine metacarpal condylar fractures is not completely understood and a developmental cause has been postulated. Objective: To investigate the subchondral bone trabecular microarchitecture of the lateral parasagittal groove and condyle in equine neonates and its adaptation with maturation and athletic activity. Methods: Ex vivo observational study. Methods: Distal metacarpi of neonates, yearlings and adult racehorses (n = 24) were harvested. Dorsal and palmar frontal histological sections, containing the lateral parasagittal groove and condyle, were studied. The sections were ...
Combination of resveratrol and 5-azacytydine improves osteogenesis of metabolic syndrome mesenchymal stem cells. Endocrine disorders have become more and more frequently diagnosed in humans and animals. In horses, equine metabolic syndrome (EMS) is characterized by insulin resistance, hyperleptinemia, hyperinsulinemia, inflammation and usually by pathological obesity. Due to an increased inflammatory response in the adipose tissue, cytophysiological properties of adipose derived stem cells (ASC) have been impaired, which strongly limits their therapeutic potential. Excessive accumulation of reactive oxygen species, mitochondria deterioration and accelerated ageing of those cells affect their multipotency...
An unexpected acoustic indicator of positive emotions in horses. Indicators of positive emotions are still scarce and many proposed behavioural markers have proven ambiguous. Studies established a link between acoustic signals and emitter's internal state, but few related to positive emotions and still fewer considered non-vocal sounds. One of them, the snort, is shared by several perrisodactyls and has been associated to positive contexts in these species. We hypothesized that this could be also the case in horses. In this species, there is a clear need for a thorough description of non-vocal acoustic signals (snorts, snores or blows are often used interch...
Detection of IgM-rheumatoid factor and anti-citrullinated protein antibodies in healthy horses and their comparison. Rheumatoid factor (RF) is used in human and veterinary medicine in the form of IgM RF traditionally to support the diagnosis of rheumatoid arthritis (RA). In the latest diagnostic criteria, presence of anti - citrullinated protein antibodies (ACPA) was added to the grading system for the diagnosis of RA in humans. A change which is not integrated or routinely used in veterinary medicine. The criteria changed partly because of RF's diagnostic shortcomings, which include its increased titer detection in humans with non-rheumatoid diseases, inability to predict the disease and increased titers ov...
Current dorsal myelographic column and dural diameter reduction rules do not apply at the cervicothoracic junction in horses. Previously published myelographic studies do not report findings at the junction between the seventh cervical (C7) and first thoracic vertebrae (T1). Modern digital radiographic equipment allows improved visualization of C7-T1. Based on clinical experience, we hypothesized that 50% reduction of the dorsal myelographic column or 20% reduction of the dural diameter, criteria commonly used as a supportive finding for spinal cord compression in the cervical vertebral column, do not apply at C7-T1. A myelographic study was performed on 12 healthy, neurologically normal horses. Our hypothesis was co...
Source and localization of ovulation-inducing factor/nerve growth factor in male reproductive tissues among mammalian species. The objectives of the study were to compare the presence and localization of ovulation-inducing factor (OIF)/nerve growth factor (NGF) in male reproductive organs and determine the abundance in ejaculates of species representative of both spontaneous and induced ovulators. We hypothesized that the protein is a widely conserved component of semen among mammals, but is most abundant in camelids. Immunohistochemical analysis was performed on tissues from the male reproductive system of llamas, rats, cattle, bison, elk, and white-tailed deer (n = 2 males/species), and the abundance of OIF/NGF in...
