Omneity® Pellets
All-In-One Vitamin & Mineral Pellet
Topic:Horses
"Horses" is a broad topic that encompasses various aspects of equine biology, behavior, and management. This category includes studies on the anatomy, physiology, and genetics of horses, as well as their behavior, nutrition, and care. Research in this area may also cover the historical and cultural significance of horses, their roles in agriculture, sport, and therapy, and the challenges associated with their conservation and welfare. The page aggregates peer-reviewed research articles and scholarly studies that explore the multifaceted relationships between humans and horses, examining both scientific and socio-economic perspectives.
Modulation of bronchial smooth muscle function in horses with heaves. Four mechanisms that modulate airway smooth muscle function in normal horses were studied in the bronchi of horses affected by the airway obstructive disease heaves. Results were compared with data from historical controls studied by the same personnel in the same laboratory. Rings from the left cranial lobar bronchus (LB1) and small bronchi (5 mm OD) were suspended in muscle baths, and the isometric tension were measured. The inhibitory nonadrenergic noncholinergic (iNANC) function was studied in LB1. After the LB1 segments were pretreated with atropine and contracted with histamine, electric...
Lipofuscin and abnormalities in colloid in the equine thyroid gland in relation to age. Lipofuscin accumulation and other histological changes in thyroid tissue, previously reported to be age-related, were studied in 31 horses aged up to 35 years. The number of lipofuscin granules relative to thyrocytes increased from birth to 5 years of age. There was a wide individual variation in the number of lipofuscin granules in thyrocytes in mature horses, but this was not directly related to age. Several abnormalities were identified in thyroid colloid. The prevalence of spherites, lipofuscin granules, nucleated cells and shreds of colloid increased with age, but the prevalence of calciu...
The cross-sectional areas of normal equine digital flexor tendons determined ultrasonographically. Fifty-two animals, comprising 22 Irish Draught crosses (Group A), 15 Thoroughbreds (Group B) and 15 ponies (Group C) were examined ultrasonographically using a 7.5 mHz linear array probe and stand-off pad. All animals were free of tendon disease as determined from clinical and ultrasonographical examination. The superficial (SDFT) and deep (DDFT) digital flexor tendons were scanned at 7 transverse (axial) levels between the carpus and metacarpophalangeal joint. Each transverse image was digitised using a commercially available frame grabber and the cross-sectional areas of each tendon at each ...
Growth hormone and prolactin concentrations in plasma of horses: sex differences and the effects of acute exercise and administration of growth hormone-releasing hormone. Three experiments were conducted to determine 1) the relationship between prolactin and growth hormone (GH) secretion in mares and the response to GH-releasing hormone (GHRH), 2) whether plasma GH and prolactin concentrations differed among mares, stallions, and geldings, and 3) whether sexual differences existed after administration of GHRH and acute exercise. In Exp. 1, 10-min blood samples were collected from 12 mares for 8 h, and GHRH (0, 45, 90, or 180 micrograms) was administered at 6 h. In Exp. 2, 15-min blood samples were collected for 4 h from 10 mares, stallions, and geldings. In Exp...
Determination of free malonaldehyde formed in liver microsomes upon CCl4 oxidation. Free malonaldehyde formed in the microsomes prepared from livers of monkey, rat, rabbit, mouse, cow, pig, dog, sheep and horse upon CCl4 oxidation was derivatized by reaction with N-methylhydrazine to form 1-methylpyrazole which was subsequently analyzed by capillary gas chromatography. Among the livers from animals tested, the monkey and rat livers produced the most malonaldehyde upon CCl4 treatment. Horse liver showed the greatest resistance to CCl4 oxidation. The gas chromatography method used in the present study exhibited an accurate and specific measurement of free malonaldehyde that mig...
Equine echocardiography–sound advice at the heart of the matter. Echocardiography is an extremely versatile tool for both the equine clinician and physiologist. There are three useful forms of echocardiography, B mode, M mode and Doppler. Together they provide complementary information on cardiac disease and haemodynamic status. B mode is used to image the cardiac chambers, valves, myocardium and pericardium. M mode allows determination of motion of cardiac structures; it is superior to B mode for timing of events and it is used to make precise measurements of the heart. Doppler echocardiography can assess intracardiac blood flow and its velocity. Echocardi...
Stress failure of pulmonary capillaries as a mechanism for exercise induced pulmonary haemorrhage in the horse. Exercise induced pulmonary haemorrhage (EIPH) is a serious problem in the Thoroughbred industry. The condition apparently occurs essentially in all Thoroughbreds in training but the mechanism has proved elusive. There is now strong evidence that the condition is caused by mechanical failure of the walls of the pulmonary capillaries when the pressure inside them rises to very high levels. It is well known that pulmonary capillaries have extremely thin walls to allow rapid exchange of respiratory gases across them. Recently we have shown that the wall stresses are very large when the capillary t...
Involvement of endogenous opioids in the regulation of LH and testosterone release in the male horse. To investigate the involvement of endogenous opioids in the regulation of gonadotrophin release in male horses, effects of the opioid antagonist naloxone (0.5 mg kg-1 i.v.) on plasma LH and testosterone concentrations and the possible influence of season and of gonadal steroids were investigated. To determine quantitative as well as qualitative changes in gonadotrophin release, LH concentrations were measured by radioimmunoassay and by an in vitro bioassay. Experiments were performed in May, August and December. In stallions, basal LH secretion in May and August was significantly higher than i...
Histological findings in corneal stromal abscesses of 11 horses: correlation with cultures and cytology. Histopathology was compared to culture results and cytology from horses with corneal stromal abscess at the Auburn University and the Ohio State University Veterinary Teaching Hospitals. Significant bacteria were not isolated in culture or seen on histopathology in any of the horses. Although most bacteria infecting equine corneas can be isolated with blood and MacConkey's agars, failure to detect bacterial growth may not rule out infection because anaerobic or intracellular bacteria would not be isolated. The inability to visualise bacterial organisms on histological sections did not rule out...
Distribution of equid herpesvirus-1 (EHV-1) in the respiratory tract of ponies: implications for vaccination strategies. Twelve adult ponies and 2 conventional foals were exposed to 10(6.6) TCID50 of Equid herpesvirus-1 (EHV-1), strain Ab4 and samples of respiratory tract tissues were recovered. Infectious virus in tissue homogenates was detected using susceptible cell monolayers and expression of viral antigens was monitored using indirect immunoperoxidase histochemistry of paraffin sections. The results illustrated the rapid dissemination of EHV-1 throughout the respiratory tract, with early replication in the lungs one day after exposure. Endothelial cell infection was prominent in all areas of the nasopharyn...
Resistance of castrated male horses to attempted establishment of the carrier state with equine arteritis virus. Twelve geldings all became infected when inoculated intranasally with the KY-84 strain of equine arteritis virus (EAV), a strain previously shown to be capable of establishing the carrier state in the stallion. With the exception of one animal that showed no effects other than pyrexia, all of the geldings developed clinical signs characteristic of equine viral arteritis (EVA). The geldings were febrile for varying periods within the range of 2-10 days after inoculation. Viraemia occurred from day 2 onwards, for periods varying from 9 to at least 19 days. Nasal shedding of virus began 2-4 days ...
Estimation of material properties in the equine metacarpus with use of quantitative computed tomography. The purpose of this study was to investigate the relationships between data obtained from quantitative computed tomography and mechanical properties in the equine metacarpus, as measured in vitro in bone specimens. Three hundred and fifty-five bone specimens from the metacarpi of 10 horses were machined into right cylinders aligned with the long axis of the bone. A computed tomographic scan of the specimens, along with a Cann-Genant K2HPO4 calibration standard, was obtained. The specimens then were compressed to failure, and the elastic modulus, yield stress, yield strain, strain energy densit...
Removal of inspissated purulent exudate from the ventral conchal sinus of three standing horses. Primary paranasal sinusitis, complicated by inspissated purulent exudate in a ventral conchal sinus, was diagnosed in 3 horses. Partial nasal obstruction, caused by axial deviation of the ventral concha, was detected endoscopically in 2 of the horses. A mass, dorsal to the maxillary molars, was detected via a lateral radiographic view of the skull of 3 horses and on the dorsoventral view of 1 of the horses. Inspissated purulent exudate was removed from the ventral conchal sinus of the horses via trephination of the conchofrontal sinus and penetration of the caudal wall of the ventral conchal s...
A comparative study of aerobic capacity and fitness in three different horse breeds (Andalusian, Arabian and Anglo-Arabian). Aerobic capacity and fitness was studied in three different horse breeds (Andalusian, Arabian and Anglo-Arabian) using a four-level exercise test of gradually increasing intensity (15, 20, 25 and 30 km/h). The lactate concentration at the first three exercise levels was significantly lower for Arabian and Anglo-Arabian horses relative to Andalusian horses, but similar for the three breeds at the last level. Arabian and Anglo-Arabian horses reached a higher rate than Andalusian horses at plasma lactate concentration of 2 mmol/l (VLA2) and 4 mmol/l (VLA4). Andalusian horses exhibited a significa...
Genetic structure of populations of beta-haemolytic Lancefield group C streptococci from horses and their association with disease. The genetic structure of beta-haemolytic Lancefield group C streptococci isolated from horses in Australia was examined by multilocus enzyme electrophoresis. The 249 isolates comprised 70 classified phenotypically as Streptococcus equi subspecies equi, 177 classified as S equi subspecies zooepidemicus and two which were unclassifiable. Forty-one electrophoretic types were identified which could be classified into three major clusters, A, B and C. Of the isolates, 178 fell into cluster B (types 4 to 22) and lay within a genetic distance of 0.36. Sixty-nine of the 70 S equi subspecies equi isola...
Effects of 0.05% chlorhexidine lavage on the tarsocrural joints of horses. In six horses, a 0.05% solution of chlorhexidine diacetate was used to lavage one tarsocrural joint; the contralateral control joint was lavaged with lactated Ringer's solution. Horses were evaluated daily for lameness. Synovial fluid samples were collected on days 1, 4, and 8 for determination of protein concentration, total and differential leukocyte counts, and mucin clot formation. After death on day 8, synovium and osteochondral samples were collected from the tarsocrural joints for examination of morphology and proteoglycan staining. Lavage with chlorhexidine solution caused lameness tha...
Insulin-like growth factor II in the horse: determination of a cDNA nucleotide sequence and expression in fetal and adult tissue. Horse cDNA for insulin-like growth factor II (IGF II) has been isolated. cDNA was synthesized from bulk mRNA and subsequently PCR-amplified and sequenced. Like its human counterpart, the mature horse IGF II peptide contains 67 amino acids with only two substitutions, isoleucine instead of valine in position 35 and asparagine instead of serine in position 36. The nucleotide homology was 92.1% between horse and human and 87.8% between horse and mouse. The isolated cDNA hybridized to multiple transcripts in fetal and adult tissues, thus confirming earlier reports on developmental expression of th...
Effect of prior lavage on bronchoalveolar lavage fluid cell population of lavaged and unlavaged lung segments in horses. Bronchoalveolar lavage (BAL) was performed on 16 horses to determine whether it caused local or diffuse inflammation in the lungs. In 7 horses, BAL was performed in both lungs twice, 48 hours apart. Although total cell counts of the BAL samples did not change significantly, there were increased numbers and percentage of neutrophils in the second lavage fluid samples. In 5 horses, BAL was performed in 1 lung and repeated 48 hours later in the same lung and in the corresponding airway in the contralateral lung. The absolute cell count and percentage of neutrophils were significantly (P = < 0....
An algorithm to describe the oxygen equilibrium curve for the thoroughbred racehorse. An algorithm to describe the oxygen equilibrium curve (OEC) of the Thoroughbred horse was derived from raw oxygen equilibrium curve data obtained under standard conditions of temperature, pH and PCO2 (Smale and Butler, 1994). This algorithm was derived by a curve-fitting procedure based on the algorithm for human blood produced by Kelman (1966). The temperature, fixed acid and net CO2 coefficients were then incorporated in the algorithm to enable the accurate calculation of % saturation from any combination of PO2, temperature, pH and PCO2. The algorithm was checked using blood gas data obtain...
Distribution of SP- and CGRP-like immunoreactive nerve fibers in the lower respiratory tract of neonatal foals: evidence for loss during development. The lungs of neonatal foals contain many nerves immunoreactive for substance P and calcitonin gene-related peptide. These nerves are closely associated with the epithelium, bronchial and pulmonary vessels and the airway smooth muscle of all intrathoracic airways, including non-cartilaginous bronchioles. Activation of sensory nerves in the respiratory epithelium could thus potentially affect, via local axon reflexes, vascular and respiratory smooth muscle in neonatal equine airways. Nerves immunoreactive for these peptides are much more widely distributed within the lung than in adult horses; t...
Pulmonary vascular pressures of thoroughbreds increase rapidly and to a higher level with rapid onset of high-intensity exercise than slow onset. Previous studies of pulmonary vascular pressures have utilised gradual incremental step exercise protocols, but in competitive racing at the track, horses perform rapid acceleration high-intensity exercise. The rate of rise in pulmonary vascular pressures under conditions of quick onset high-intensity exercise is unknown. Catheter mounted manometers, whose in vivo signals were matched with pressure signals obtained via transducers connected to fluid-filled lumens from same cardiovascular sites, were used to compare right heart and pulmonary vascular pressures in 8 healthy Thoroughbreds perform...
Blood lactate disappearance after maximal exercise in trained and detrained horses. The influence of training on blood lactate concentrations during treadmill exercise and a 40-minute inactive recovery period was examined in seven trained and seven detrained thoroughbred horses. Lactate concentrations were measured in venous blood collected at the end of each exercise state, and at intervals for 40 minutes afterwards. Measurements were made of maximum oxygen uptake (VO2max, ml kg-1 min-1), VLA4 (velocity at which blood lactate concentration was 4 mmol litre-1); LA8 (lactate concentration [mmol litre-1] during exercise at 8 m sec-1), peak lactate (highest lactate concentration...
Effect of sample handling on measurement of plasma glucose and blood lactate concentrations in horses before and after exercise. Collection of a satisfactory blood sample requires special procedures to prevent changes in glucose and lactate content after the sample has been obtained. Changes in measured plasma glucose and blood lactate concentrations attributable to anticoagulants and storage procedures, respectively, were examined in blood samples obtained from horses at rest and after exercise. To evaluate the effect of anticoagulants on measured plasma glucose concentration, blood was preserved with either sodium fluoride/potassium oxalate or lithium heparin. Measured plasma glucose concentration in blood obtained at...
Equilibrium unfolding studies of horse muscle acylphosphatase. The stability and equilibrium unfolding behaviour of horse muscle acylphosphatase have been studied by denaturing the protein under various conditions of temperature, pH, and urea concentration. Far-ultraviolet circular dichroism (CD) and nuclear magnetic resonance (NMR) spectroscopy indicate that this small monomeric protein unfolds reversibly and cooperatively. Thermodynamic parameters, the Gibbs free energy delta G and enthalpy delta H of unfolding, have been estimated for denaturation of the protein from NMR and CD data as 19 kJ mol-1 and 350 kJ mol-1, respectively. CD and 1H-NMR results s...
