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.
Clothier J, Small A, Hinch G, Brown WY.The persistent endocrinological effects of perinatal stress due to gestational immaturity in horses are unknown, although effects have been reported in other livestock species. This pilot study tested the hypothesis that persistent adrenocortical dysregulation is present in horses that were gestationally immature at birth by assessing the salivary cortisol response to exogenous ACTH. Case horses (n = 10) were recruited with histories of gestation length < 315 d or dysmaturity observable through neonatal signs. Positive controls (n = 7) and negative controls (n = 5) were recruited wher...
Scardia A, Mariani Pimenta EL, Ross Russell RI, Jones GJ, Staffieri F.The aim of this study was to evaluate the validity of the SpO/FiO diagram in estimating gas exchange in horses under general anaesthesia. In this prospective, controlled clinical study were included 10 horses under general anaesthesia. FiO was progressively reduced with the following steps: 0.6, 0.4, 0.3 and 0.21; SpO was recorded at each step. An arterial blood sample was collected at the steps of 1.0 and 0.21, to calculate intrapulmonary shunt with the Fshunt formula. The Fshunt value calculated at 0.21 FiO was defined as "Fshunt 0.21", the one calculated at 1.0 FiO as "Fshunt 1.0". The FiO ...
Auckburally A, Wiklund MK, Lord PF, Hedenstierna G, Nyman G.To measure changes in pulmonary perfusion during pulsed inhaled nitric oxide (PiNO) delivery in anesthetized, spontaneously breathing and mechanically ventilated ponies positioned in dorsal recumbency. Methods: 6 adult ponies. Methods: Ponies were anesthetized, positioned in dorsal recumbency in a CT gantry, and allowed to breathe spontaneously. Pulmonary artery, right atrial, and facial artery catheters were placed. Analysis time points were baseline, after 30 minutes of PiNO, and 30 minutes after discontinuation of PiNO. At each time point, iodinated contrast medium was injected, and CT angi...
Midon M, Yamada DI, Zangirolami Filho D, Natalini CC, Escobar A, Clark-Price SC.This randomized double-blinded study evaluated the recovery from isoflurane anesthesia in horses receiving doxapram and xylazine. 6 horses were anesthetized 4 times (minimum of 2-week washout period). Anesthesia was performed with xylazine (0.6 mg/kg), ketamine (2.2 mg/kg), midazolam (0.1 mg/kg), and maintained with isoflurane for 90 minutes. At recovery, horses received one of the following randomized treatments: RX: xylazine (0.2 mg/kg), RXD1: xylazine (0.2 mg/kg) and doxapram (0.1 mg/kg), RXD2: xylazine (0.2 mg/kg) and doxapram (0.2 mg/kg), or RS: saline. Recoveries were rope-assisted and e...
Radcliffe RM, Bookbinder LC, Liu SY, Tomlinson JE, Cook VL, Hurcombe SDA, Divers TJ.Blood transfusion is a lifesaving treatment for horses with acute hemorrhage and other causes of anemia. Transfusions improve oxygen delivery to the tissues via increased blood volume and hemoglobin concentration. Certain aspects of equine blood transfusion are challenging, especially in the field situation, and practitioners may be unfamiliar or feel overwhelmed with the process. An understanding of the indications, materials, methods, and techniques as well as donor selection and possible complications will help practitioners successfully implement blood transfusion in clinical practice. Met...
Schroeder EL, Gardner AK, Mudge MC.Cecal or colonic gas tympany of any cause may result in increased intraabdominal pressure, causing a significant decrease in venous return and cardiac output. Trocarization of the large colon or cecum in the event of large intestinal tympany may resolve gas distension and accompanying increased intraabdominal pressures sufficiently enough to promote resolution of a displaced large colon. Furthermore, trocarization of the medical colic may decrease morbidity and mortality associated with severe intraabdominal hypertension. Methods: This how-to description details the technique of transcutaneous...
Thane K, Uricchio C, Frank N.Diagnosis of pituitary pars intermedia dysfunction (PPID) using the thyrotropin-releasing hormone (TRH) stimulation test requires blood collection 10 minutes after TRH injection; it is unknown if small differences in timing affect test results. Objective: To determine whether early or late sampling results in a significant (≥10%) difference in plasma adrenocorticotropic hormone (ACTH) concentration compared to standard 10-minute sampling. Methods: Twenty-four healthy adult horses with unknown PPID status. Methods: In this prospective study, subjects underwent a single TRH stimulation test, ...
Briski O, Salamone DF.During the past 2 decades, intracytoplasmic sperm injection (ICSI) has become a routine technique for clinical applications in humans. The widespread use among domestic species, however, has been limited to horses. In horses, ICSI is used to reproduce elite individuals and, as well as in humans, to mitigate or even circumvent reproductive barriers. Failures in superovulation and conventional in vitro fertilization (IVF) have been the main reason for the use of this technology in horses. In pigs, ICSI has been successfully used to produce transgenic animals. A series of factors have resulted in...
Kirsch K, Fercher C, Horstmann S, von Reitzenstein C, Augustin J, Lagershausen H.Show jumping is a highly specialized equestrian discipline that requires technical skill but also power and fitness. Monitoring the horses' aerobic performance is therefore essential in order to verify whether the training has induced the desired cardiovascular and muscular adaptations. This study therefore aimed at evaluating the validity of non-specific and discipline-specific field exercise tests for objective evaluation of aerobic performance in show jumpers. For this purpose, data obtained from horses competing at Junior and Young Rider level during show jumping competitions as well as fi...
Griffin RA, Swegen A, Baker MA, Ogle RA, Smith N, Aitken RJ, Skerrett-Byrne DA, Fair S, Gibb Z.Stallions experience transient fluctuations in fertility throughout the breeding season. Considering pregnancy diagnoses cannot be ascertained until ~14 days postbreeding, the timely detection of decreases in stallion fertility would enhance industry economic and welfare outcomes. Therefore, this study aimed to identify the proteomic signatures reflective of short-term fertility fluctuations and to determine the biological mechanisms governing such differences. Using liquid chromatography-mass spectrometry (LC-MS/MS), we compared the proteomic profile of semen samples collected from commercia...
Kinsella HM, Hostnik LD, Snyder HA, Mazur SE, Kamr AM, Burns TA, Mossbarger JC, Toribio RE.The equine neonate is considered to have impaired glucose tolerance due to delayed maturation of the pancreatic endocrine system. Few studies have investigated insulin sensitivity in newborn foals using dynamic testing methods. The objective of this study was to assess insulin sensitivity by comparing the insulin-modified frequently sampled intravenous glucose tolerance test (I-FSIGTT) between neonatal foals and adult horses. This study was performed on healthy neonatal foals (n = 12), 24 to 60 hours of age, and horses (n = 8), 3 to 14 years of age using dextrose (300 mg/kg IV) and insulin (0....
Malik CE, Wong DM, Dembek KA, Wilson KE.To determine the accuracy of 2 interstitial glucose-monitoring systems (GMSs) for use in horses compared with a point-of-care (POC) glucometer and standard laboratory enzymatic chemistry method (CHEM). Methods: 8 clinically normal adult horses. Methods: One of each GMS device (Dexcom G6 and Freestyle Libre 14-day) was placed on each horse, and blood glucose concentration was measured via POC and CHEM at 33 time points and compared with simultaneous GMS readings. An oral glucose absorption test (OGAT) was performed on day 2, and glucose concentrations were measured and compared. Results: Glucos...
Maia BT, Vendruscolo CDP, de Souza AF, Zoppa ALDV.The neurovascular bundle of the equine distal cannon can dynamically vary with limb position, and this can affect the performance of low 4- or 6-point block. This study aims to identify and describe the anatomical position and variations of the lateral and medial palmar/plantar nerve at the metacarpal/metatarsal distal level in horses by ultrasonography. Eight mares underwent ultrasound examination on the lateral and medial palmar/plantar sides of the metacarpus/metatarsus. Images were obtained for measurements of the cross-sectional area of the nerve, distances between the nerve and the skin ...
Gastal MO, Pastorello M, Godoi DB, Gastal EL.The aim of this study was to compare the dominant follicle (DF) and gonadotropin dynamics for 9 days before ovulation in postpartum lactating (PP Lactating) versus non-postpartum cycling (N-PP Cycling) mares. Every PP Lactating mare on the day of parturition was paired with a N-PP Cycling mare, and the data analyses considered the partum-ovulation interval (POI) and the postpartum interovulatory interval (PPIOI) in PP Lactating mares and two interovulatory intervals in N-PP Cycling mares. The results of the present study revealed several novel and unique aspects of DF development and FSH and L...
Norton NM, Santschi E, Fischer KJ.The etiology of subchondral bone cysts (SBCs) is not fully understood. Mechanical trauma and fluid pressure are two mechanisms believed to cause their formation and growth. The equine stifle joint provides a natural animal model for studying SBCs. Computed tomography images of an extended yearling cadaveric stifle joint were segmented using ScanIP to isolate bones and relevant soft tissues. Three model geometries were created to simulate cyst sizes of approximately 0.03 cm (C1), 0.5 cm (C2), and 1 cm (C3). A uniform pressure resulting in 3000 N force was applied at the proximal end of the fem...
Morrell JM, Rocha A.One of the most commonly encountered challenges in equine breeding is endometritis, which can be difficult to resolve and causes considerable economic losses to the industry. It is a multifactorial condition, developing as an exaggerated form of the normal physiological response to breeding. Seminal plasma proteins, spermatozoa, bacteria and debris initiate an inflammatory response; the resulting fluid and neutrophils are then cleared from the uterus along with the debris. However, in some mares, the response is prolonged or exaggerated, with much fluid formation and neutrophil infiltration le...
Lanier CJ, Taintor JS, Christopherson PW, Spangler EA.Acidemia in sick or injured horses is often due to lactic acid accumulation. Alterations in platelet function and hemostasis are among numerous deleterious effects caused by decreased physiologic pH. Objective: We aimed to evaluate the effect of hyperlactatemia and resultant acidemia on platelet aggregation in equine whole blood using impedance aggregometry. Methods: Platelet aggregation was measured using the Multiplate analyzer in whole blood from 34 healthy horses at baseline and after in vitro addition of lactic acid to adjust the pH. Platelet aggregation of each sample was quantified by t...
Neto da Silva AC, Costa AL, Teixeira A, Alpoim-Moreira J, Fernandes C, Fradinho MJ, Rebordão MR, Silva E, Ferreira da Silva J, Bliebernicht M....In older mares, increasing collagen fibers (fibrosis) in the endometrium and oviduct predisposes to sub-fertility and infertility. In this study, (i) gene transcription of collagen (qPCR: COL1A1, COL1A2, COL3A1, COL5A1); (ii) total collagen protein (hydroxyproline); (iii) collagen distribution (Picrosirius red staining; polarized light microscopy); and (iv) microvascular density (Periodic acid-Schiff staining), were evaluated in mares' placenta, and related to mares age, and placenta and neonate weights. Samples were collected from the gravid horn, non-gravid horn, and body of the placenta fro...
Bergmann W, de Lest CV, Plomp S, Vernooij JCM, Wijnberg ID, Back W, Gröne A, Delany MW, Caliskan N, Tryfonidou MA, Grinwis GCM.Gross morphology of healthy and degenerated intervertebral discs (IVDs) is largely similar in horses as in dogs and humans. For further comparison, the biochemical composition and the histological and biochemical changes with age and degeneration were analyzed in 41 warmblood horses. From 33 horses, 139 discs and 2 fetal vertebral columns were evaluated and scored histologically. From 13 horses, 73 IVDs were assessed for hydration, DNA, glycosaminoglycans, total collagen, hydroxyl-lysyl-pyridinoline, hydroxylysine, and advanced glycation end-product (AGE) content. From 7 horses, 20 discs were ...
Sterkenburgh T, Schulz-Kornas E, Nowak M, Staszyk C.Equine mastication, as well as dental wear patterns, is highly important for the development of treatments in equine dentistry. During the last decades, the stress and strain distributions of equine teeth have been successfully simulated using finite element analysis. Yet, to date, there is no simulation available for dental tooth wear in equines. In this study, we developed a simplified two-dimensional computer simulation of dental wear. It provides a first tentative explanation for the development of the marked physiological inclination of the occlusal surface and for pathological conditions...
Byambaragchaa M, Choi SH, Joo HE, Kim SG, Kim YJ, Park GE, Kang MH, Min KS.Equine chorionic gonadotropin (eCG), produced by the endometrial cups of the placenta after the first trimester, is a specific glycoprotein that displays dual luteinizing hormone (LH)-like and follicle-stimulating hormone (FSH)-like effects in non-equid species. However, in equidaes, eCG exhibits only LH-like activity. To identify the specific biological functions of glycosylated sites in eCG, we constructed the following site mutants of N- and O-linked glycosylation: eCGβ/αΔ56, substitution of α-subunit N-linked glycosylation site; eCGβ-D/α, deletion of the O-linked glycosylation sites ...
Potter SJ, Bamford NJ, Baskerville CL, Harris PA, Bailey SR.Ponies and some horse breeds such as Andalusians exhibit an 'easy keeper' phenotype and tend to become obese more readily than other breeds such as Standardbreds. Various hypotheses have been proposed, including differences in appetite or metabolic efficiency. This study aimed to investigate the effect of breed on nutrient digestibility. Ponies, Standardbreds and Andalusian horses were adapted to consuming either a control fibre-based diet ( = 9), a hypercaloric cereal-rich diet ( = 12) or a hypercaloric fat-rich diet ( = 12) over 20 weeks. Total faecal collection was performed over 24 h to de...
Fuentes-Romero B, Muñoz-Prieto A, Cerón JJ, Martín-Cuervo M, Iglesias-García M, Aguilera-Tejero E, Díez-Castro E.Obesity and its associated complications, such as metabolic syndrome, are an increasing problem in both humans and horses in the developed world. The expression patterns of resistin differ considerably between species. In rodents, resistin is expressed by adipocytes and is related to obesity and ID. In humans, resistin is predominantly produced by inflammatory cells, and resistin concentrations do not reflect the degree of obesity, although they may predict cardiovascular outcomes. The aim of this study was to investigate the usefulness of resistin and its relationship with ID and selected ind...
Leemans B, Bromfield EG, Stout TAE, Vos M, Van Der Ham H, Van Beek R, Van Soom A, Gadella BM, Henning H.We describe the development of two methods for obtaining confluent monolayers of polarized, differentiated equine oviduct epithelial cells (EOEC) in Transwell inserts and microfluidic chips. EOECs from the ampulla were isolated post-mortem and seeded either (1) directly onto a microporous membrane as differentiated EOECs (direct seeding protocol) or (2) first cultured to a confluent de-differentiated monolayer in conventional wells, then trypsinized and seeded onto a microporous membrane (re-differentiation protocol). Maintenance or induction of EOEC differentiation in these systems was achiev...
Calixto LC, Martinez JR.Cortisol is a hormone secreted by the adrenal glands that is stimulated by physiological and pathological factors and has been studied widely in equids, but not in mules. The objectives of this study were to obtain a reference value for serum cortisol in mules destined for agricultural activities and to identify age- and gender-related differences in the value. The concentration was obtained in blood samples using a commercial sandwich ELISA specific for cortisol. The concentration was 96.3 ± 40.6 ng/ml and similar between age groups and genders.
Domino M, Borowska M, Kozłowska N, Zdrojkowski Ł, Jasiński T, Smyth G, Maśko M.Infrared thermography (IRT) was applied as a potentially useful tool in the detection of pregnancy in equids, especially native or wildlife. IRT measures heat emission from the body surface, which increases with the progression of pregnancy as blood flow and metabolic activity in the uterine and fetal tissues increase. Conventional IRT imaging is promising; however, with specific limitations considered, this study aimed to develop novel digital processing methods for thermal images of pregnant mares to detect pregnancy earlier with higher accuracy. In the current study, 40 mares were divided i...
Schade J, de Souza AF, Vincensi LC, Fonteque JH.The objective of this study was to assess the influence of the metacarpophalangeal (MCP) joint angle on the transversal area (TA) and mean echogenicity (ME) of the superficial digital flexor tendon (SDFT) and suspensory ligament (SL) in gaited horses. Ultrasound images were obtained from 50 healthy adult horses of the Mangalarga Marchador (MM; n=25) and Campeiro (n=25) breeds. Static and dynamic angles of the MCP joint were measured from photographs and video recordings. Higher ME values were evinced for the SL only in the group with the smaller dynamic angles of the MCP joint in the MM horses...
Niikura T, Tsogtgerel M, Niikura C, Wada H, Kanzawa S, Fujiwara T, Nambo Y.The objective of this study was to examine the effect of prostaglandin F2α (dinoprost) and oxytocin administration on uterine polymorphonuclear neutrophil counts in the Japanese heavy draft mare. To compare polymorphonuclear neutrophil (PMN) counts in the endometrium, a total of 162 samples were collected from 54 estruses of 47 mares (before ovulation, day 0, and day 2) using a double-guarded cytology brush. Dinoprost (PG; 5 mg) was administered intramuscularly (i.m.) only once, on day 0, whereas oxytocin (OT; 20 U i.m.) was administered three times at 12-hr intervals starting on day 0. The p...
Cherdchutham W, Sukhong P, Sae-Oueng K, Supanwinijkul N, Wiangnak K, Srimuang J, Apichaimongkonkun T, Limratchapong S, Petchdee S.The medical treatment of horses with nephrosplenic entrapment (NSE) of the large colon through administrating phenylephrine and rolling during general anesthesia was effective and less expensive than surgical treatment. However, the selection of drugs for non-surgical treatment of NSE is not a usual method for clinical practice. This study aimed to identify the effects of combined drugs on the cardiac and splenic response in horses and provide information on the NSE of the large colon for clinical application. Methods: Six healthy Thai native crossbred horses were enrolled in this study. Horse...
Vergara-Hernandez FB, Nielsen BD, Robison CI, Fabus TA, Kompare JL, LeCompte Lazić RA, Colbath AC.The main factors influencing speed in athletes are stride length (SL) and stride rate (SR). However, conflict remains whether SL or SR is the key determinant of higher speeds. Quarter Horses (QH) generally reach higher speeds in their races than do Thoroughbreds (TB). However, the influence of SL and SR on this greater speed is unclear. Therefore, the main objective of this study was to compare SL and SR in QH and TB raced in short (sprint) and long (classic) distances. We hypothesized that QH have a higher SR in comparison to TB, and SR decreases as distance increases. Two race distances were...
Rivero JL, Hill EW.Skeletal muscles in horses are characterised by specific adaptations, which are the result of the natural evolution of the horse as a grazing animal, centuries of selective breeding and the adaptability of this tissue in response to training. These adaptations include an increased muscle mass relative to body weight, a great locomotor efficiency based upon an admirable muscle-tendon architectural design and an adaptable fibre-type composition with intrinsic shortening velocities greater than would be predicted from an animal of comparable body size. Furthermore, equine skeletal muscles have a ...
Nieto JE, MacDonald MH, Braim AE, Aleman M.Horses are exquisitely sensitive to bacterial endotoxin and endotoxaemia is common in colic cases. In this study, gene expression of inflammatory cytokines was characterised in the blood of healthy horses following i.v. administration of lipopolysaccharide (LPS). Six horses received an LPS infusion and 6 controls received an equivalent volume of saline. Gene expression of genes encoding interleukin (IL)-1alpha, IL-1beta, IL-6, IL-8, and tumour necrosis factor-alpha (TNF-alpha) was quantified by real-time PCR. Gene expression of all inflammatory cytokines was upregulated following administratio...
Toribio RE.Calcium and phosphate have structural and nonstructural functions, and their concentrations in the extracellular compartment are affected by the physiologic status of the animal as well as diseases. Important progress in understanding calcium and phosphorus metabolism in healthy and diseased horses and foals has been made in recent years. For example, several studies have confirmed that hypocalcemia is frequent in horses with gastrointestinal disease and that calcium endocrine dysregulation is associated with survival in foals. One critical point in the homeostasis of these minerals is their i...
Kisiday JD, McIlwraith CW, Rodkey WG, Frisbie DD, Steadman JR.To evaluate the effects of single- and double-spin preparations of platelet-rich plasma (PRP) on anabolic and catabolic activities of cartilage and meniscal explants in vitro. Methods: Single- and double-spin PRP was prepared using laboratory processing or commercial kits. The cellular contents were quantified, and each PRP was mixed in equal quantities with cell culture medium and added to cartilage or meniscus explant cultures, with or without interleukin 1 β (IL-1β). Extracellular matrix synthesis was quantified over 24 hours via (35)S-sulfate and (3)H-proline incorporation, while gene ex...
Svala E, Jin C, Rüetschi U, Ekman S, Lindahl A, Karlsson NG, Skiöldebrand E.The glycoprotein lubricin contributes to the boundary lubrication of the articular cartilage surface. The early events of osteoarthritis involve the superficial layer where lubricin is synthesised. Objective: To characterise the glycosylation profile of lubricin in synovial fluid from horses with osteoarthritis and study secretion and degradation of lubricin in an in vitro inflammation cartilage model. Methods: In vitro study. Methods: Synovial fluid samples collected from horses with joints with normal articular cartilage and structural osteoarthritic lesions; with and without osteochondral f...
Weber JA, Freeman DA, Vanderwall DK, Woods GL.This study was conducted to identify embryonic products whose secretion was temporally associated with the oviductal transport period of the mare. Chemicals secreted by oviductal-transport-stage equine embryos were identified by incubating Day 6 or Day 7 early uterine embryos with 35S-methionine/cysteine, 3H-progesterone, or 3H-arachidonic acid for 24 h, and subsequently identifying radioactively labeled proteins (SDS-PAGE; n = 3 embryos), steroids (HPLC; n = 3 embryos), or prostaglandins (HPLC; n = 3 embryos) in the culture medium. Early uterine embryos secreted 116.1 +/- 45.5 pg of prostagla...
Marlin DJ, Scott CM, Roberts CA, Casas I, Holah G, Schroter RC.Whereas the efficacy of cold water cooling of horses has been demonstrated by several studies, the dynamics of temperature changes within and between compartments (primarily muscle, blood [core], skin and deep core [rectal]) have not been investigated. Changes in body temperature associated with cold water cooling were investigated in the hyperthermic horse. Muscle (TMU), pulmonary artery (TPA), rectal (TREC), tail-skin (TTSK) and coat surface (TCOAT) temperatures, were monitored continuously in 5 Thoroughbred horses during and after exercise in hot humid (30 degrees C and 80% RH) conditions o...
Ahmed YA, Tatarczuch L, Pagel CN, Davies HM, Mirams M, Mackie EJ.Post-proliferative chondrocytes in growth cartilage are present in two forms, light and dark cells. These cells undergo hypertrophy and die by a mechanism that is morphologically distinct from apoptosis, but has not been characterized. The aims of the current study were to document the ultrastructural appearance of dying hypertrophic chondrocytes, and to establish a culture system in which the mechanism of their death can be examined. Methods: Growth cartilage from fetal and growing postnatal horses was examined by electron microscopy. Chondrocytes were isolated from epiphyseal cartilage from ...
Abraham G, Zizzadoro C, Kacza J, Ellenberger C, Abs V, Franke J, Schoon HA, Seeger J, Tesfaigzi Y, Ungemach FR.Horses develop recurrent airway obstruction (RAO) that resembles human bronchial asthma. Differentiated primary equine bronchial epithelial cells (EBEC) in culture that closely mimic the airway cells in vivo would be useful to investigate the contribution of bronchial epithelium in inflammation of airway diseases. However, because isolation and characterization of EBEC cultures has been limited, we modified and optimized techniques of generating and culturing EBECs from healthy horses to mimic in vivo conditions. Results: Large numbers of EBEC were obtained by trypsin digestion and successfull...
Stewart HL, Pitta D, Indugu N, Vecchiarelli B, Hennessy ML, Engiles JB, Southwood LL.Previous studies have identified alterations in the faecal microbiota of horses with colic; however, further work is needed to interpret these findings. Objective: To compare the faecal microbiota of horses presenting for colic at hospital admission, day 1 and day 3/discharge and with different colic duration and lesion locations. Methods: Prospective observational clinical study. Methods: Faecal samples were collected from 17 colic cases at hospital admission, on day 1 and on day 3 post-admission or at the time of hospital discharge if prior to 72 hours. Faecal samples were extracted for gen...
Meyers S, Bulkeley E, Foutouhi A.The biological nature of age-related declines in fertility in males of any species, including stallions, has been elusive. In horses, the economic costs to the breeding industry are frequently extensive. Mitochondrial function in ejaculated sperm, which is essential for sperm motility, is reflected by adenosine triphosphate production, mitochondrial oxidative efficiency and production of reactive oxygen species, and that this balance may become compromised in ageing stallions and during the process of cryopreservation. This presentation will focus on mitochondrial integrity and function as an ...
Marshall JF, Blikslager AT.Nonsteroidal anti-inflammatory drugs (NSAIDs) are commonly used in the management of pain and endotoxaemia associated with colic in the horse. While NSAIDs effectively treat the symptoms of colic, there is evidence to suggest that their administration is associated with adverse gastrointestinal effects including right dorsal colitis and inhibition of mucosal barrier healing. Several studies have examined the pathophysiology of NSAID associated effects on the large and small intestine in an effort to avoid these complications and identify effective alternative medications. Differences in the re...
Ebert DW, Roberts C, Farrar SK, Johnston WM, Litsky AS, Bertone AL.Measurements of absolute total reflectance were recorded from weight-bearing (n=9) and nonweight-bearing (n=9) equine articular cartilage specimens from 300 to 850 nm using a spectrophotometer with integrating sphere attachment. Following correction of measured spectra for interfacial reflections and edge losses, Kubelka-Munk theory was applied to estimate absorption and scattering coefficient, one-dimensional light intensity distribution, and light penetration depth. Kubelka-Munk absorption coefficients ranged from ∼7 cm-1 at 330 nm to ∼1 cm-1 at 850 nm. A localized absorption peak wa...
Beeley JG, Eason R, Snow DH.A protein, latherin, with unusual surface activity was isolated from horse sweat by gel filtration and ion-exchange chromatography. The protein has a Stokes radius, determined by gel filtration, of 2.47 nm, and in the ultracentrifuge sediments as a single species with S20,W 2.05 S, indicating an Mr of 24,400. On SDS/polyacrylamide-gel electrophoresis the molecule behaves as a single peptide chain of apparent Mr 20,000. Latherin contains a high proportion of hydrophobic amino acids (37.2%), and the leucine content (24.5%) is exceptionally high. The unusual composition of the protein may account...
Williams MA, Harrison PM.Horse ferritin was fractionated both by starch-gel electrophoresis and by gel filtration on Sephadex G-200. Monomer fractions contained up to 98% of monomer and oligomer fractions up to 76% of oligomers as determined by quantitative electron microscopy. Percentages obtained from electron micrographs correlated well with analytical starch-gel electrophoretograms and ultracentrifuge patterns. Amino acid analyses of monomer- and oligomer-enriched fractions showed no significant differences. Ferritin oligomers did not apparently dissociate on dilution for electron microscopy or on storage. Apoferr...
Banks KL, McGuire TC.Surface receptors on peripheral blood neutrophils and monocytes from normal and immunodeficient horses have been studied. Sheep erythrocytes (SRBC) coated with IgG, IgM, and complement but not IgG(T), readily bound to normal equine monocytes and neutrophils. More than 4000 molecules of IgG were required to sensitize each SRBC for adherence to monocytes, and more than 12,000 molecules were required for adherence to neutrophils. Young horses with a severe combined immunodeficiency had an almost total absence of lymphocytes, but normal numbers of monocytes and neutrophils. The number of receptors...
Mellor DJ, Beausoleil NJ.Horses engaged in strenuous exercise display physiological responses that approach the upper functional limits of key organ systems, in particular their cardiorespiratory systems. Maximum athletic performance is therefore vulnerable to factors that diminish these functional capacities, and such impairment might also lead to horses experiencing unpleasant respiratory sensations, i.e., breathlessness. The aim of this review is to use existing literature on equine cardiorespiratory physiology and athletic performance to evaluate the potential for various types of breathlessness to occur in exerci...
Woodward EM, Christoffersen M, Campos J, Squires EL, Troedsson MH.The objectives were to: (1) investigate the associations of age and endometrial biopsy score with uterine fluid retention after insemination; and (2) determine if a strict classification of susceptibility to persistent breeding-induced endometritis (PBIE) based on biopsy score, endometrial cytology, and fluid retention after inseminations, is consistent over subsequent breeding seasons. In Experiment 1, 57 mares were inseminated with 10(9) freeze-killed sperm during estrus and evaluated for uterine fluid retention 48 h and 96 h after insemination. Comparisons were made between fluid retention ...
Wilk I, Wnuk-Pawlak E, Janczarek I, Kaczmarek B, Dybczyńska M, Przetacznik M.It was assumed that a horse with its rider body weight found in the upper limit may negatively impact the horse's welfare. The objective of this paper was to analyze the differences in body temperature and selected heart rate parameters in horses in response to physical exercise accompanied by various rider's body weight loads. The study was carried out on 12 leisure, 10-15-year-old warmblood geldings. The horses were ridden by two equally qualified riders whose body weights were about 20% and 10% of the average body weight (BW) of the animals (about 470 kg). Each rider rode each of the 12 hor...
Sharma AK, Paramasivam M, Srinivasan A, Yadav MP, Singh TP.Lactoferrin is a monomeric glycoprotein with a molecular mass of approximately 80 kDa. The three-dimensional structure of mare diferric lactoferrin (mlf) has been determined at 2.6 A resolution. The protein crystallizes in the space group P 212121with a=85.2 A, b=99.5 A, c=103.1 A with a solvent content of 55 % (v/v). The structure was solved by the molecular replacement method using human diferric lactoferrin as the model. The structure has been refined using XPLOR to a final R -factor of 0.194 for all data in the 15-2.6 A resolution range. The amino acid sequence of mlf was determined using ...
Armstrong RB, Essén-Gustavsson B, Hoppeler H, Jones JH, Kayar SR, Laughlin MH, Lindholm A, Longworth KE, Taylor CR, Weibel ER.The purpose of this study was to describe the relationships between 16 physiological, biochemical, and morphological variables presumed to relate to the oxidative capacity in quadriceps muscles or muscle parts in Standardbred horses. The variables included O2 delivery (blood flow) and mean capillary transit time (MTT) during treadmill locomotion at whole animal maximal O2 consumption (VO2max, 134 +/- 2 ml.min-1 x kg-1), capillary density and capillary-to-fiber ratio, myoglobin concentration, oxidative enzyme activities, glycolytic enzyme activities, fiber type populations, and fiber size. Thes...
Gibb Z, Butler TJ, Morris LH, Maxwell WM, Grupen CG.Excessive reactive oxygen species generation during sex sorting and cryopreservation of stallion sperm leads to DNA fragmentation, lipid peroxidation, and motility loss. In this study we investigated whether antioxidant supplementation during sex sorting and cryopreservation could ameliorate the effects of reactive oxygen species on stallion sperm. In experiment 1, the postthaw characteristics of stallion sperm (N = 9) cryopreserved in the presence or absence of catalase (200 U/mL), cysteine (0.2 mg/mL), or quercetin (0.15 mM) was examined. Motility and acrosome integrity were assessed at 0, 1...
Stradaioli G, Sylla L, Zelli R, Chiodi P, Monaci M.The effect of orally administered l-carnitine on the quality of semen obtained from stallions with different semen qualities was investigated. Four stallions with proven fertility (high motility group, HM) and with normal seminal characteristics (>50% progressive motility and > 80 x 10(6) spermatozoa/ml), and four questionable breeders (low motility group, LM) with <50% of sperm progressive motility and < 80 x 10(6) spermatozoa/ml, received p.o. 20 g of l-carnitine for 60 days. Blood and semen samples were collected before treatment (T0) and after 30 (T1) and 60 days (T2). Semen ev...
Jäderkvist K, Andersson LS, Johansson AM, Árnason T, Mikko S, Eriksson S, Andersson L, Lindgren G.In a previous study it was shown that a nonsense mutation in the DMRT3 gene alters the pattern of locomotion in horses and that this mutation has a strong positive impact on trotting performance of Standardbreds. One aim of this study was to test if racing performance and trotting technique in the Nordic (Coldblood) trotters are also influenced by the DMRT3 genotype. Another aim was to further investigate the effect of the mutation on performance in Standardbreds, by using a within-family analysis and genotype-phenotype correlations in a larger horse material than in the previous study. We gen...
Hlastala MP, Bernard SL, Erickson HH, Fedde MR, Gaughan EM, McMurphy R, Emery MJ, Polissar N, Glenny RW.Recent studies using microspheres in dogs, pigs and goats have demonstrated considerable heterogeneity of pulmonary perfusion within isogravitational planes. These studies demonstrate a minimal role of gravity in determining pulmonary blood flow distribution. To test whether a gravitational gradient would be more apparent in an animal with large vertical lung height, we measured perfusion heterogeneity in horses (vertical lung height = approximately 55 cm). Four unanesthetized Thoroughbred geldings (422-500 kg) were studied awake in the standing position with fluorescent microspheres injected ...
Shin EK, Rijkers T, Pastink A, Meek K.We reported previously that the genetic SCID disease observed in Arabian foals is explained by a defect in V(D)J recombination that profoundly affects both coding and signal end joining. As in C.B-17 SCID mice, the molecular defect in SCID foals is in the catalytic subunit of the DNA-dependent protein kinase (DNA-PKCS); however, in SCID mice, signal end resolution remains relatively intact. Moreover, recent reports indicate that mice that completely lack DNA-PKCS also generate signal joints at levels that are indistinguishable from those observed in C.B-17 SCID mice, eliminating the possibilit...
Harman AM, Moore S, Hoskins R, Keller P.Here we provide confirmation that the 'ramp retina' of the horse, once thought to result in head rotating visual behaviour, does not exist. We found a 9% variation in axial length of the eye between the streak region and the dorsal periphery. However, the difference was in the opposite direction to that proposed for the 'ramp retina'. Furthermore, acuity in the narrow, intense visual streak in the inferior retina is 16.5 cycles per degree compared with 2.7 cycles per degree in the periphery. Therefore, it is improbable that the horse rotates its head to focus onto the peripheral retina. Rather...
Pfeiffenberger M, Bartsch J, Hoff P, Ponomarev I, Barnewitz D, Thöne-Reineke C, Buttgereit F, Gaber T, Lang A.Fractures in horses-whether simple fractures with just one clean break, or incomplete greenstick with stress fractures, or complications such as shattered bones can all be either minimal or even catastrophic. Thus, improvement in fracture healing is a hallmark in equine orthopedics. The fracture healing process implements a complex sequence of events including the initial inflammatory phase removing damaged tissue, re-establishment of vessels and mesenchymal stromal cells, a soft and hard callus phase closing the fracture gap as well as the remodeling phase shaping the bone to a scar-free tiss...
