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Topic:Equine Health
Equine health encompasses the study and management of diseases, disorders, and overall well-being of horses. It involves understanding various physiological systems, preventive care, and treatment strategies to maintain optimal health in equine populations. Common areas of focus include nutrition, infectious diseases, orthopedic conditions, and reproductive health. Research in equine health aims to advance knowledge on diagnostic methods, therapeutic interventions, and management practices that improve horse welfare and performance. This page collects peer-reviewed research studies and scholarly articles that explore the diverse aspects of equine health, offering insights into current findings and advancements in the field.
Skeletal muscle characteristics in red blood cell normovolaemic and hypervolaemic standardbred racehorses. Muscle biopsy specimens from the middle gluteal muscle were studied in 16 red blood cell hypervolaemic (Group HV) and 19 normovolaemic (Group NV) Standardbred racehorses. All horses were stallions, 4-8 years old and having similar mean racing performance values, as described by an individual selection index value. All horses raced regularly but those in Group HV did not perform as expected and were therefore referred to the clinics for exercise tolerance testing. Muscle biopsy specimens were analysed for fibre type distribution (Type I, IIA and IIB), fibre area and relative fibre area. In addi...
Temporal changes in concentrations of amino acids in plasma and whole blood of healthy neonatal foals from birth to two days of age. Temporal changes, as well as differences in distribution, in concentrations of 24 amino acids in plasma and whole blood of neonatal foals were determined from birth to 2 days of age. In addition, differences in concentrations of amino acids in plasma between mare and foal pairs were determined at birth. Significant (P < 0.05) hypoaminoacidemia existed for 15 amino acids in plasma of foals at birth, compared with mares (paired t-test). Concentrations of 7 amino acids (aspartate, glutamate, glutamine, glycine, hydroxyproline, phenylalanine, proline) in plasma of foals were higher (P 0.05). S...
Sensory nerve conduction velocity of the caudal cutaneous sural and medial cutaneous antebrachial nerves of adult horses. Maximal conduction velocities of compound action potentials evoked by stimuli of 2 times threshold in the caudal cutaneous sural (CCSN) and medial cutaneous antebrachial (MCAN) nerves were determined by averaging potentials evoked and recorded through percutaneous needle electrodes. Mean maximal conduction velocities of compound action potentials were: CCSN = 61.3 +/- 2.0 meters/second (m/s) and MCAN = 56.4 +/- 2.8 m/s. To confirm accuracy of our percutaneous recordings, compound action potentials were recorded through bipolar chlorided silver electrodes from the exposed surfaces of fascicles ...
Influence of estrous cycle stage on adhesion of Streptococcus zooepidemicus to equine endometrium. Equine endometria representative of Kenney's categories I, II, and III were incubated in vitro with phosphate buffer, Streptococcus pneumoniae, or S zooepidemicus. Endometrial tissues from mares in estrus and diestrus were first categorized according to Kenney's classification, then were tested for adherence of S pneumoniae and S zooepidemicus to the epithelia. Bacteria were not observed when the endometrial tissue was incubated with phosphate buffer or S pneumoniae. There was no statistical difference in attachment of S zooepidemicus to endometrial tissue from mares in estrus or diestrus if e...
Haematological, bone marrow and clinical chemical changes in neonatal foals given canine recombinant granulocyte-colony stimulating factor. Five Thoroughbred and Quarter Horse cross foals were given 20 micrograms canine recombinant granulocyte-colony stimulating factor (rcG-CSF) per kg bwt intramuscularly (i.m.) on the day of birth and 10 micrograms rcG-CSF/kg for 13 additional days. During this time and for an additional 21 days haematology, bone marrow and clinical chemical analyses were performed. After one day of rcG-CSF administration leucocyte and neutrophil counts increased from 9.16 x 10(9)/l to 23.44 x 10(9)/l and from 6.45 x 10(9)/l to 19.61 x 10(9)/l, respectively. The counts continued to increase for the next 3-4 days ...
Chondrocyte-fibrin matrix transplants for resurfacing extensive articular cartilage defects. Cartilage resurfacing by chondrocyte implantation, with fibrin used as a vehicle, was examined in large (12 mm) full-thickness articular cartilage defects in horses. Articular chondrocytes, isolated from a 9-day-old foal, were mixed with fibrinogen and injected with thrombin, in a 1:1 mixture, into 12 mm circular defects on the lateral trochlea of the distal femur of eight normal horses. The contralateral femoropatellar (knee) joint served as a control in which the defect was left empty. Synovial fluid from the femoropatellar joints was sampled on days 0, 4, 7, 30, 120, and 240 postoperatively...
Effects of the opioid antagonist naloxone on release of luteinizing hormone in mares during the anovulatory season. To investigate an involvement of endogenous opioids in the regulation of circannual changes in reproductive activity, effects of the opioid antagonist naloxone on the concentration of immunoreactive and bioactive luteinizing hormone (LH) in plasma were measured in mares during the anovulatory season. Naloxone (0.5 mg/kg i.v.) caused a significant increase (P < 0.05) in immunoreactive as well as bioactive LH concentration in plasma. The amplitude of the increase in LH concentrations measured with an in vitro bioassay was more pronounced than the amplitude of the increase in LH secretion dete...
An in vitro biomechanical investigation of an interlocking nail for fixation of diaphyseal tibial fractures in adult horses. The compressive, bending and torsional mechanical properties of osteotomized adult equine tibiae stabilized with an interlocking intramedullary nail (nail-tibia composite) were compared with those of intact tibiae to determine the clinical applicability of the the nail for repair of tibial fractures in adult horses. The mean yield load, failure load, and stiffness for the nail-tibia composites were significantly less (P < .05) than those for the intact tibiae in all loading configurations. The mean compressive yield load for the nail-tibia composites was greater than the compressive load ca...
Down-regulation followed by re-expression of equine CD4 molecules in response to phorbol myristate acetate. The regulatory effects of phorbol myristate acetate (PMA) on the expression of the CD4 molecule on horse T cells were investigated. On both peripheral blood lymphocytes and thymocytes, PMA resulted in a rapid and transient down-regulation of equine CD4 expression, but had no such effect on the surface expression of equine CD5, CD8 or major histocompatibility complex (MHC) class I and class II molecules. Over 75% of the surface CD4 molecules per cell were lost after a 4 h exposure to PMA at 37 degrees C. The regulation of equine CD4 expression induced by PMA was temperature dependent and revers...
Exercise-induced hyperthermia as a possible mechanism for tendon degeneration. Mathematical modelling of tendon thermodynamics predicted that the temperature of the central core of the equine superficial digital flexor tendon would plateau at 11 degrees C above the tendon surface temperature during a sustained gallop. A mean temperature differential (between tendon core and surface) of 5.4 (S.E. +/- 1.0) degrees C was demonstrated in vivo in four horses. Peak intra-tendinous temperatures in the range 43-45 degrees C were recorded. Temperatures above 42.5 degrees C are known to result in fibroblast death in vitro [Hall (1988) Radiobiology for the Radiologist, 3rd Edn., pp...
XX male syndrome in a cryptorchid stallion. A bilateral cryptorchid stallion with mild development of mammary glands was identified as an XX male by karyotyping. Necropsy revealed underdeveloped accessory sex organs and hypoplastic, inguinally located testes that were deficient of spermatogonia. Evaluation of routine hormonal profiles (without karyotyping) would have failed to diagnose this syndrome.
Report of the First International Workshop on Equine Leucocyte Antigens, Cambridge, UK, July 1991. The First International Workshop on Equine Leucocyte Antigens was organized and convened for the purposes of identifying immunologically relevant cell surface molecules of equine leucocytes and establishing a system of nomenclature for those molecules. Participating members of the workshop represented the majority of laboratories world-wide engaged in the tasks of production and characterization of equine leucocyte and lymphocyte markers using monoclonal antibodies. The workshop confirmed the identification of several equine CD molecules described previously by individual laboratories, and in ...
Significance for exercise capacity of some electrocardiographic findings in racehorses. Various cardiorespiratory and metabolic indices were assessed during treadmill exercise in Thoroughbred and Standardbred racehorses with T wave changes in 4 or more leads on the electrocardiogram or second-degree atrio-ventricular (AV) block, and in horses that had no abnormalities on clinical examination, resting electrocardiography or upper respiratory tract endoscopy. No significant differences in heart rate, plasma lactate concentration, arterial blood gases, oxygen uptake, run time, peak velocity, or blood and red cell volumes were found between normal horses and horses with T wave change...
Clinical efficacy and safety of clenbuterol HCl when administered to effect in horses with chronic obstructive pulmonary disease (COPD). A field study of 239 horses was conducted to determine the efficacy and safety of clenbuterol HCl, a beta 2-adrenergic bronchodilator, when administered incrementally to effect in the treatment of chronic obstructive pulmonary disease (COPD). The severity of COPD (heaves) and response to treatment was determined by clinical evaluation; an overall 'heaveiness rating' (OHR) was assigned at each observation. The horses were treated orally b.i.d. with clenbuterol (as Ventipulmin Syrup), beginning with the lowest dosage of 0.8 micrograms/kg. On day 10 of treatment at the effective dose (0.8, 1.6, 2...
Technique for long-term ileal cannulation in ponies. A T-cannula was fitted permanently into the ileum of ten mature ponies to quantify the role of the prececal and postileal segments of the digestive tract in equine nutrition studies. The ponies were anesthetized, positioned in left lateral recumbency, and the distal small intestine was exteriorized through a right paralumbar incision. A silastic T-cannula was inserted through a 2-cm longitudinal incision into the lumen of the ileum, on the antimesenteric surface, and sutured to the ileum. The stem of the cannula was exteriorized through a 2-cm circular skin incision, 6 cm caudal to the 16th ri...
Effect of helium-induced ventilatory unloading on breathing and diaphragm EMG in awake ponies. Two questions were addressed in this study: 1) Does respiratory resistive unloading (inspired O2 fraction = 0.21, inspired He fraction = 0.79) elicit a compensatory reduction in stimulation of the diaphragm? 2) Do diaphragm and lung afferents contribute to compensatory responses to unloading? Ten intact (I), five diaphragm-deafferented (DD), four hilar nerve-denervated (HND), and seven DD+HND adult ponies were studied at rest and during mild and moderate treadmill exercise. During steady-state unloading at rest, duration of the diaphragm electromyogram (EMGdi) was less (P < 0.05) than contr...
In vitro mechanical properties and failure mode of the equine (pony) cranial cruciate ligament. In vitro failure modes and mechanical properties of the equine cranial cruciate ligament (CCL) were evaluated in 15 stifle joints from 10 ponies. Ponies were from 3 to 25 years of age and weighed from 122 to 208 kg. Femur-CCL-tibia specimens were mounted in 48 degrees of flexion, distracted until a 500-g tensile preload was achieved, and then tested by tensile loading to failure. Specimens failed by complete midsubstance CCL rupture (n = 9), combined tibial insertion avulsion fracture and midsubstance CCL rupture (n = 4), and combined femoral origin avulsion fracture and midsubstance CCL ruptu...
Arthroscopic removal of osteochondral fragments from the proximal interphalangeal joint of the pelvic limbs in three horses. Osteochondral fragments detected in the proximal interphalangeal joint in the pelvic limbs of 3 horses (2 Standardbreds and 1 Thoroughbred) caused joint enlargement and lameness. Fragments were removed by use of arthroscopy. Accurate placement of the arthroscope into the dorsal joint space was necessary to obtain an adequate view of the fragments. After surgery, 2 of the horses resumed racing without joint problems, and the third was in training to race. High-detail radiographs are necessary to detect osteochondral fragments in horses with joint enlargement or lameness localized to the proxima...
Effects of training on blood lactate-running speed relationship in thoroughbred racehorses. In this study the effects of training history on the results of a standardized two-speed test in competing Thoroughbreds were investigated during a racing season. For nine Thoroughbreds, 1,755 training days were recorded. Within the observation period each horse completed a two-speed field test at intervals of 6-8 wk to determine its running velocity (v) eliciting blood lactate concentrations of 4 (v4) and 12 mmol/l (v12). Horses performed 29 two-speed tests. Changes of v4 and v12 in a horse between two consecutive tests were used to assess effects of training history variables calculated for ...
Bilateral tibial metaphyseal stress fractures associated with physitis in a foal. A 7-month-old Appaloosa foal had bilateral hind limb lameness and was unable to rise from recumbency without assistance. Lameness could be exacerbated by tarsal flexion and a firm swelling at the distomedial aspect of the tibias was associated with a marked pain response when palpated. Radiography revealed enlargement of the distal tibial metaphysis physis (compared with normal), and radiolucent fissure lines extending proximally from the physis into the metaphysis at its medial aspect. Treatment included rest and dietary adjustment. Although clinical signs initially resolved following treatme...
Effect of body direction on heart rate in trailered horses. To determine whether body direction in a trailer affects the degree to which a horse is excited (and presumably stressed) during transport, heart rates were measured in 8 Thoroughbred geldings transported over a 32-km route of county roads while tethered facing forward or backward in a 4-horse stock trailer. Heart rates also were measured on the horses while they were tethered facing forward or backward in the same trailer while it was parked. Heart rates decreased during the first 10 minutes for both groups, and remained stable after the first 15 minutes. Heart rates were not significantly di...
Initial characterization of equine inhibin. Inhibin has been characterized from a number of mammals; however, it has not been extensively studied in horses. Western blot analysis was used to examine the size heterogeneity of equine inhibin alpha- and beta-subunits. The distribution of equine inhibin activity from the initial sizing column (S-200, 25 x 94 cm) indicated that the majority of equine inhibin activity was present as larger-molecular-size forms. When the large forms were analyzed by Western blot in nonreducing conditions, alpha-subunit bands were detected at 40,000 M(r), 56,000 M(r), 80,000 M(r), and 90,000 M(r); beta a reacti...
Endoscopic anatomy and map of the equine bronchial tree. To develop a bronchoscopic map of the equine respiratory tree, the major airways of the lungs of 6 healthy Thoroughbred horses were systematically explored with a flexible fibreoptic endoscope through a tracheostomy while the horses were sedated in stocks. With the carina as the reference point, measurements were made of distances to the branches of the major airways using markers on the shaft of the endoscope. All branches were explored until the narrowing of their diameters prevented further advancement of the endoscope. Positions of origins of branches from the parent bronchus were recorded...
Differential scanning calorimetric studies of superficial digital flexor tendon degeneration in the horse. Differential scanning calorimetry (DSC) of equine superficial digital flexor tendons revealed the presence of a small exothermic peak at 23 degrees C of unknown origin, and a large endothermic peak at 70 degrees C due to denaturation of cross-linked collagen fibres. In the central degenerated core of damaged tendons the denaturation temperature remained at 70 degrees C but the enthalpy decreased in relation to the extent of degeneration of the tendon. We suggest that this reduction in enthalpy is due to depolymerisation and denaturation of the collagen fibres. This contention is supported by t...
Variation in expression of MHC class II antigens on horse lymphocytes determined by MHC haplotype. A panel of monoclonal antibodies was used to characterize the expression of equine Major Histocompatibility Complex (MHC) class II antigens on lymphocytes of horses of different MHC types. MHC class II antigen expression was compared between adult horses and foals, and the level of expression of MHC class II antigens on horse T cell subpopulations was also determined. Peripheral blood lymphocytes (PBL) from young and adult healthy horses of different MHC haplotypes were labeled with the antibodies and assayed by single- and two-color immunofluorescence flow cytometry. A variation in the expres...
Variation in the concentration of long chain free fatty acids in equine plasma over 24 hours. The primary aim of this study was to examine the within-day variation in the concentration of total and individual long chain free fatty acids (C > 14) in normally fed horses. Plasma samples were collected over a 24 h period from 12 resting horses during three separate sessions (six horses in the first session and three in the second and third). Samples were analysed for individual long chain free fatty acids (FFA) and glucose. During normal feeding, the predominant FFA in plasma were palmitic (C16:0), linoleic (C18:2), oleic (C18:1), stearic (C18:0) and linolenic (C18:3). Together these ac...
