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.
Investigation of hydration processes of the equine hoof via nuclear magnetic resonance microscopy. To examine the distribution of water in hoof wall specimens of horses via nuclear magnetic resonance (NMR) microscopy and determine changes in water distribution during hydration. Methods: 4 hoof wall specimens (2 obtained from the dorsum and 1 each obtained from the lateral quarter and lateral heel regions) of the stratum medium of healthy hooves of 1 horse. Methods: Equine hoof wall specimens were examined via NMR microscopy. Proton density-weighted 3-D images were acquired. Changes during water absorption were assessed on sequential images. Results: The inner zone of the stratum medium had ...
Locomotor Inhibition in Adult Horses Faced to Stressors: A Single Postpartum Experience May be Enough! Despite the number of postpartum handling that a newborn experiences, few studies focus on their long-term consequences. In rats, regular long separations from the mother, during the early life, led to modifications of the locomotor activity when the animal is confronted to a stressor. In horses, one component of the behavioral response to stressful situation is active locomotion. We wondered if the routine postpartum handling undergone by foals, would affect their level of reactivity or the way they express their stress, when older. One single prolonged bout of handling just after birth clear...
Expression of aquaporin water channels in equine endometrium is differentially regulated during the oestrous cycle and early pregnancy. The expression of 12 different aquaporin subtypes in equine endometrium was examined at the mRNA and protein level. Endometrial samples were obtained during anoestrus, oestrus, 8, and 14 days after ovulation in non-pregnant mares, and 14 days after ovulation in pregnant mares. Quantitative PCR revealed a time-dependent pattern for all aquaporin subtypes examined except for AQP10 and 12. AQP3, 5 and 7 showed highest mRNA abundance 8 days after ovulation, while AQP0 and 2 were most abundant at Day 14 of the cycle in non-pregnant mares. At 14 days of pregnancy, AQP1, 4, 8, 9 and 11 displayed ...
Ovulation-inducing factor in seminal plasma: a review. Ovulation in mammals involves pulsatile release of GnRH from the hypothalamus into the hypophyseal portal system with subsequent release of LH from the anterior pituitary into systemic circulation. Elevated circulating concentrations of LH induce a cascade of events within the mature follicle, culminating in follicle rupture and evacuation. The broad classification of species as either spontaneous or induced ovulators is based on the type of stimulus responsible for eliciting GnRH release from the hypothalamus. In spontaneously ovulating species (e.g., human, sheep, cattle, horse, pigs), relea...
Evaluation of motion correction processing in equine bone scintigraphy by Scheffé’s method of paired comparisons. Equine bone scintigraphy is usually performed with horses in standing position under sedation. However, swaying motion often leads to poor-quality images. To examine the usefulness of motion correction (MC) processing, equine bone scintigrams were evaluated using Scheffé's method of paired comparisons. A significant difference in evaluation scores was detected by analysis of variance (F test, P<0.01). According to all observers, Yardstick analysis scores were higher for images use of MC processing than for those no use of MC processing, for all parts. Overall scores of 5 observers were as ...
The effect of radio electric asymmetric conveyer treatment on sperm parameters of subfertile stallions: a pilot study. The Radio Electric Asymmetric Conveyer (REAC) has been mostly applied to treat symptoms related to psychological stress. In the study, we demonstrated the effect of REAC-Veterinary Neuro Psycho Physical Optimization (VNPPO) treatment protocol on sperm parameters of subfertile (n=11) and fertile (n=4) stallions. Subfertile stallions showed a reduced sperm concentration, progressive motility and normal morphology compared to fertile stallions. An increase in progressive sperm motility and quality of sperm morphology was found in subfertile stallions after the REAC-VNPPO treatment. The positive e...
Effects of meloxicam and phenylbutazone on equine gastric mucosal permeability. Newer NSAIDs that more selectively target the induced isoform of the cyclooxygenase enzyme (COX2) activity might reduce adverse effects while preserving therapeutic benefits of these drugs. Objective: To compare the effect of oral administration of multiple dose rates of meloxicam and phenylbutazone (PBZ) on gastric mucosal integrity in horses. Methods: Twenty-five light breed horses. Methods: In vivo toxicity study. Horses were randomly assigned to 5 treatment groups, receiving placebo, PBZ (4.4 mg/kg PO q12h day 1, 2.2 mg/kg PO q12h for 4 days, 2.2 mg/kg PO q24h for 9 days), or 3 dose rates ...
Effect of cytokines and ovarian steroids on equine endometrial function: an in vitro study. Regulation of immune-endocrine interactions in the equine endometrium is not fully understood. The aims of the present study were to: (1) investigate the presence of tumour necrosis factor alpha (TNF), interferon gamma (IFNG), Fas ligand (FASLG) and their receptors in the mare endometrium throughout the oestrous cycle; and (2) assess endometrial secretory function (prostaglandins), angiogenic activity and cell viability in response to TNF, oestradiol (E2), progesterone (P4) and oxytocin (OXT). Transcription of TNF and FASLG mRNA increased during the early and late luteal phase (LP), whereas IF...
Identification of recombinant human relaxin-2 in equine plasma by liquid chromatography-high resolution mass spectrometry. Relaxin (RLX) is a peptide hormone belonging to the relaxin-like peptide family. Relaxin-2 (RLX-2), a heteromeric polypeptide consisting of an A-chain (24 amino acids) and a B-chain (29 amino acids) linked together by two inter-chain disulfide bonds, is the main circulating RLX hormone in human. Due to its ability to dilate blood vessels surrounding the smooth muscles via induction of nitric oxide resulting in the increase of blood and oxygen supplies to the muscles, it may enhance athletic performance and is therefore banned in horseracing, equestrian competitions, and human sports. In order ...
Tenogenic differentiation of equine mesenchymal progenitor cells under indirect co-culture. Adult bone marrow mesenchymal stem cells (BM-MSCs) are a potential cell source for tendon repair in direct cell therapy and tissue engineering investigations. The purpose of this study was to evaluate the tenogenic induction of undifferentiated BM-MSCs under indirect co-culture technique with trimmed native tendon tissue. Since the horse represents a preferred species to study tendon regenerative strategies, this work was conducted on equine BM-MSCs. Methods: Equine BM-MSCs were co-cultured in a transwell system with tendon tissue fragments. The BM-MSC tenogenic differentiation was evaluated b...
Glucocorticoid overexposure in neonatal life alters pancreatic beta-cell function in newborn foals. Studies in humans and animals have linked abnormal programming of adult tissue function to excess glucocorticoids during perinatal development. The current study investigated the hypothesis that physiological variations in glucocorticoid concentrations during early neonatal life of the foal alter the secretory responses of the pancreatic β cells 2 and 12 wk after treatment. Spontaneously delivered foals received either saline or long-acting ACTH for 5 d from 1 d after birth to maintain an endogenous rise in cortisol concentrations. Starting at d 10, pancreatic β cell function was studied usi...
Correlation between corneal sensitivity and quantity of reflex tearing in cows, horses, goats, sheep, dogs, cats, rabbits, and guinea pigs. Guinea pigs have a very low threshold of corneal sensitivity and at the same time nearly no reflex tearing compared to dogs, cats, and horses. The question arose whether there is a general correlation between corneal sensitivity and the quantity of reflex tearing. Methods: Totally 160 animals of 8 different species (20 animals per species) were investigated. Methods: The corneal touch threshold (CTT) was measured with a Cochet-Bonnet esthesiometer. The palpebral fissure length (PFL) was measured with a calliper ruler. The Schirmer tear test (STT) was modified by adapting the width of the STT s...
Daily variability of forced oscillometry parameters in horses suffering recurrent airway obstruction, a pilot study. The aim of the study was to analyse the day-to-day variability of the respiratory resistance (R(rs)) and the reactance (X(rs)) in 5 horses in a status of remission of recurrent airway obstruction by forced oscillometry system (FOS). Furthermore, the effects of stabling, outdoor and room temperature and humidity on these parameters were determined. Mean R(rs) at oscillation frequencies 1, 1.5, 2 and 3 Hz were all significantly higher in the morning than in the afternoon, while X(rs) was not significantly affected by time of the day. R(rs) was significantly different on various sampling days at ...
64, XX, SRY-negative, testicular DSD syndrome in a Lusitano horse. Here is reported a disorder of sex development found in the Portuguese Lusitano horse breed. The complex genital phenotype included mammary glands, abdominal testes without epididymis, connected through oviducts to pelvic hypoplastic uterine horns and fused vulvar labia majora from which protruded ventrally a penis-like structure. This structure was presented in a reversed position, the urethral opening placed dorsally in the glans. However, it was functional both for micturition and erection. The horse exhibited female micturition posture and aggressive male-like behaviour, including flehmen,...
The promoter region of interferon-gamma is hypermethylated in neonatal foals and its demethylation is associated with increased gene expression. While born with a limited production, foals' interferon-gamma (IFN-γ) expression increases after birth. The underlying mechanisms remain unknown. DNA methylation is considered to be involved. Therefore, the DNA methylation status of the Ifng promoter in CD4(+) cells from neonatal foal was determined using a methylation-specific PCR (MSP), and its relevance to IFN-γ mRNA expression was estimated. The effect of environment on the DNA methylation was also evaluated by comparing ponies that were kept in a barn versus those on pasture. The DNA in the Ifng promoter was hypermethylated and its deme...
Sevoflurane inhibits equine myeloperoxidase release and activity in vitro. To investigate the effects of the volatile anaesthetic sevoflurane on the release of total and active myeloperoxidase (MPO) by non-stimulated and stimulated polymorphonuclear neutrophils (PMNs) in whole blood from healthy horses. Methods: In vitro experimental study. Methods: Adult healthy horses. Methods: Samples of whole venous blood were collected and incubated in air or in air plus 2.3% or 4.6% sevoflurane for 1 hour. PMNs were stimulated with N-formyl-methionyl-leucyl-phenylalanine (fMLP), with a combination of cytochalasin B (CB) and fMLP or with phorbol myristate acetate (PMA). Total an...
Expression of inhibin/activin subunits in the equine uteri during the early pregnancy. The establishment of equine pregnancy is a unique and long process during which a series of physical and possibly biochemical interactions are required between the conceptus and uterus. In this study, we investigated the expression pattern of inhibin/activin subunits in the uterus during early pregnancy. The uteri from four adult mares on cyclic day 13 or pregnancy day 25 were obtained. Immunohistochemical experiments suggested that inhibin/activin subunits were immunolocalized in the luminal and glandular epithelium on pregnancy day 25. In addition, the inhibin α and inhibin/activin βB subu...
Investigation of a non-invasive method of assessing the equine circadian clock using hair follicle cells. A comprehensive understanding of the equine circadian clock involves the evaluation of circadian clock gene expression. A non-invasive and effective method for detecting equine clock gene expression has yet to be established. Currently, research surrounding this area has relied on collecting tissue biopsies or blood samples that can often be costly, time consuming and uncomfortable for the animal. Methods: Five mares were individually stabled under a light-dark (LD) cycle that mimicked the external environmental photoperiod during a time of year corresponding with the vernal equinox. Hair foll...
Kisspeptide in the estrous mare: is it an appropriate ovulation-inducing agent? Kisspeptides (KiSS) are a recently discovered family of neuropeptides with a central role in regulating the onset of reproductive function in all animals studied to date. We have established biological and physiological evidence for KiSS signaling in the mare. The objective of the current study was to evaluate the physiological and behavioral responses of mares repeatedly given the equine-specific kisspeptpin decapeptide (eKp-10, YRWNSFGLRY-NH(2)) in an effort to shorten the interovulatory period. Administration of eKp-10 (0.5 mg iv every 4 h) to mares beginning on Day 16 postovulation (Group ...
Active hyaluronidase 2 expression in the granulation tissue formed in the healing process of equine superficial digital flexor tendonitis. Upregulation of hyaluronidase 2 (HYAL2), one of somatic hyaluronidase (HAase), was demonstrated in granulation tissue during the healing of equine superficial digital flexor tendon injuries. The activity of HAase was assessed by hyaluronan (HA)-containing gel zymography and in situ zymography using frozen sections obtained from normal and injured tendon tissues. Elevated HAase activity was identified in the extract from the tendinopathic tissues, with lower levels of the activity in normal tendons. In situ zymography using fluorescently-labeled HA demonstrated HAase activity in the granulation...
The influence of casein and urea as nitrogen sources on in vitro equine caecal fermentation. To access the fermentative response of equine caecal microbial population to nitrogen availability, an in vitro study was conducted using caecal contents provided with adequate energy sources and nitrogen as limiting nutrient. Two nitrogen (N) sources were provided, protein (casein) and non-protein (urea). Caecal fluid, taken from three cannulated horses receiving a hay-concentrate diet, was mixed with a N-free buffer-mineral solution. The influence of four N levels (3.7, 6.3, 12.5 or 25 mg of N in casein or urea) was studied using the gas production technique. Total volatile fatty acids (VFA)...
Optimization of leukocyte concentration in platelet-rich plasma for the treatment of tendinopathy. Numerous methods are available for platelet-rich plasma (PRP) generation, but evidence defining the optimum composition is lacking. We hypothesized that leukocyte-reduced PRP would result in lower inflammatory cytokine expression compared with concentrated-leukocyte PRP and that maintaining the platelet:white blood cell (WBC) ratio would compensate for the effect of increased WBC concentration. Methods: Blood and flexor digitorum superficialis tendons were collected from young adult horses. Three PRP groups were generated with the same platelet concentration but different WBC concentrations: i...
Early experience with continuous positive airway pressure (CPAP) in 5 horses — a case series. This case series is the first report of the use of CPAP (continuous positive airway pressure) ventilation in adult horses. Two horses and 3 ponies anesthetized for orthopedic procedures in lateral recumbency received 10 cm H(2)O CPAP. During anesthesia, arterial oxygen partial pressure tended to increase and arterial carbon dioxide pressure tended to increase despite increased minute ventilation index. The measured cardiovascular parameters were within physiologic limits. Cette série de cas est le premier rapport sur l’utilisation de la ventilation spontanée en pression positive continue ...
Assessment of oxidative stress biomarkers in exhaled breath condensate and blood of Thoroughbred foals. This study reports preliminary data on systemic and local biomarkers of oxidative stress (OS) in Thoroughbred foals. Blood and exhaled breath condensate (EBC) were sampled from 13 foals on two farms. Values of reactive oxygen metabolites (d-ROMs), biological antioxidant potential (BAP), antioxidant barrier (OXY-ads), thiol antioxidant barrier (SHp) and advanced oxidation protein products (AOPPs) were determined in blood, while EBC samples were assayed for hydrogen peroxide (H(2)O(2)) levels. Systemic and local OS biomarkers did not differ between farms and gender. Increased oxidative stress in...
Effects of oxytocin, lipopolysaccharide (LPS), and polyunsaturated fatty acids on prostaglandin secretion and gene expression in equine endometrial explant cultures. Increased secretion of prostaglandin F(2)α (PGF(2)α) within the uterus because of uterine inflammation can cause luteolysis and result in early embryonic loss. Supplementation with polyunsaturated fatty acids (PUFAs) has been shown to influence PG production in many species, although the effects on the mare remain unknown. The present study aimed to determine fatty acid uptake in equine endometrial explants and evaluate their influence on PG secretion and expression of enzymes involved in PG synthesis in vitro. Equine endometrial explants were treated with 100 μM arachidonic acid, eicosapen...
ADP-induced platelet aggregation after addition of tramadol in vitro in fed and fasted horses plasma. Adenosine diphosphate (ADP)-induced platelet aggregation in fed and fasted horses after addition of tramadol hydrochloride was evaluated in vitro. On 10 horses citrated blood samples were collected 2h after feeding (fed animals) and 21 h after feeding (fasted animals). Final concentrations of ADP 1 and 0.5 μM, and tramadol hydrochloride (1, 15, 30, 45 and 60 min after the addition of tramadol) were used to determine the maximum degree and initial velocity of platelet aggregation. Repeated measures multifactor analysis of variance (MANOVA) was used to evaluate the effect of feeding/fasting con...
Effect of the size of evacuated blood collection tubes on total carbon dioxide concentration in equine plasma. To determine whether plasma total CO(2) concentrations would vary with the size of the evacuated tube used to collect blood samples. Methods: Randomized crossover study. Methods: Convenience sample of 20 healthy adult horses. Methods: Jugular venous blood was collected from horses in random order into 8 types of evacuated tubes: 2-mL glass, 2- or 3-mL plastic or plastic plasma separator, 4- or 6-mL plastic, and 10-mL glass or plastic. Total CO(2) concentrations in plasma were measured with a biochemistry analyzer. Data were analyzed via repeated-measures ANOVA and multivariate regression. Resu...
