Equine veterinary journal. Supplement.
Discontinued
Publisher:
Equine Veterinary Journal, Ltd. Hobokken, NJ : Wiley (2009)
Frequency: Irregular
Country: United States
Language: English
Author(s):
British Equine Veterinary Association.
Start Year:1983 - 2013
ISSN:
Impact Factor
2.2
2022
| NLM ID: | 9614088 |
| (DNLM): | SR0062474(s) |
| (OCoLC): | 10429490 |
| Classification: | W1 EQ968 |
Pathophysiology of dorsal displacement of the soft palate in horses. Dorsal displacement of the soft palate (DDSP) is an intermittent obstructive upper airway condition that occurs in athletic horses during high-intensity exercise. The pathogenesis of this condition is unknown, but may involve epiglottic hypoplasia, malformation, or neuromuscular dysfunction. In this paper, we report on investigations into the pathophysiology of DDSP. In 3 separate experiments, Standardbred horses were exercised on a high-speed treadmill at speeds corresponding to 50, 75 and 100% of maximum heart rate. The upper airway was evaluated by videoendoscopy and measurement of tracheal...
Effects of potassium intake on potassium, sodium and fluid balance in exercising horses. The aim of this study was to investigate the adaptation to an increased potassium (K+) intake in horses and to study whether the regulation of the post exercise K+, sodium (Na+) and fluid balances were altered by an increased K+ intake. Four Standardbred horses were fed 2 levels (4.1 and 5.4 mmol/kg bwt/day) of K+ for 17 days in a crossover design. The effects on K+, Na+ and fluid balance were studied both at rest and in response to 29 km exercise. K+, Na+ and fluid intakes and outputs were balanced within 24 h after a new diet had been introduced. Adaptation consisted primarily of an increase...
Blood glucose clearance after feeding and exercise in polysaccharide storage myopathy. Polysaccharide storage myopathy (PSSM) in Quarter Horses (QH) and QH crosses is a glycogen storage disorder in which blood glucose clearance and insulin sensitivity, following an i.v. or oral glucose challenge, are enhanced. Exercise is known also to enhance glucose uptake into skeletal muscle in many animal species. Therefore, the purpose of this study was to compare the effect of exercise on glucose clearance in PSSM and control horses when an oral carbohydrate meal (8 Mcal sweet feed) was fed following either 12 h fasting alone (NEX protocol) or following fasting and a standard exercise pro...
Oral nitroglycerin paste did not lower pulmonary capillary pressure during treadmill exercise. We hypothesised that 22.5 mg of oral nitroglycerin would cause pulmonary vasodilation and therefore decrease pulmonary capillary pressure in horses during strenuous exercise. Six horses were assigned to exercise twice, once with no medication (control) and once with nitroglycerin (22.5 mg orally) in random order. Horses were exercised for 3 min each at 75, 90 and 100% of maximal heart rate (HRmax) with a 2 min period of walking between each period of exertion. Pulmonary artery and oesophageal pressures were recorded continuously. Subsequent analysis was carried out on the pulmonary arterial pr...
The effect of supramaximal exercise on equine platelet function. When blood is collected into sodium citrate in the proportion of 9 parts blood:1 part sodium citrate, the concentration of plasma sodium citrate in the sample will depend on the packed cell volume (PCV) of the blood sample. This difference in plasma sodium citrate concentration secondary to alterations in PCV significantly affects human platelet aggregation responses. Since horses attain a high PCV in response to high-intensity exercise we investigated the effect of differences in sample plasma sodium citrate concentration on equine platelet aggregability. In addition, low molecular weight hep...
Digestible energy expenditure in grazing activity of growing horses. Ten Thoroughbred yearlings (5 females and 5 males) were used to examine the effect of time of grazing on pasture forage and digestible energy (DE) intake, bodyweight gain and DE expenditure in grazing activity. Five females were grazed for 17 h/day (LTG), 5 males were grazed for 7 h/day (STG) and they were fed differently. As a result, DE intake from pasture forage of LTG horses and STG horses was 27.3 and 12.7-13.9 Mcal/day, respectively. The average daily gain (ADG) of LTG and STG horses was 0.37 and 0.39-0.61 kg/day, respectively. The regression lines between DE intake and ADG of both group...
Effects of pre-exercise frusemide administration and post exercise anaesthesia on cardiopulmonary and acid-base parameters and blood and plasma volumes in horses exercised supramaximally to fatigue. Six horses were randomly assigned to receive either frusemide (F) (0.5 mg/kg i.v.) or an equivalent volume of saline (S) i.v., 4 h prior to treadmill exercise. Horses were instrumented to enable measurement of heart rate (HR), systolic (SAP), mean (MAP), and diastolic (DAP) carotid arterial pressures, pulmonary artery pressure (PAP), central venous pressure (CVP), pulmonary arterial temperature (TEMP), blood gases, and cardiac output (CO). Plasma (PV) and blood volumes (BV) were measured using 2 injections of Evan's Blue dye. Baseline parameters were recorded while the horse stood quietly. Hor...
Effect of feeding thoroughbred horses a high unsaturated or saturated vegetable oil supplemented diet for 6 months following a 10 month fat acclimation. This study looked at the effect of feeding diets supplemented with either a predominantly saturated or unsaturated vegetable oil over a prolonged period to exercising horses. Eight Thoroughbred horses were assigned to 2 diet treatments and for 10 months were fed Timothy hay and oats, together with a fortified sweet feed supplemented with either a predominantly unsaturated (Un) or a saturated (S) vegetable oil so that approximately 19% DE (Digestible Energy) came from dietary fat and approximately 12% from either the Un or S source (AC). An increased amount of Un or S fortified sweet feed, repl...
Phytate and phosphorus movements in the digestive tract of horses. This experiment was conducted to study phytate degradation and the effect of dietary phytate level on phosphorus absorption in the gastrointestinal tract of horses. Six Thoroughbred horses were fed diets containing low-phytate diet or high-phytate diet for 5 days. The diets were supplemented with Cr2O3 as an unabsorbable marker. The horses were killed 3 h after the last feeding and digesta in some segments of the intestine were collected. In both dietary groups, the daily passage of phytate phosphorus was decreased in the upper small intestine and in the lower large intestine. The daily passag...
Biomechanical analysis of horse shoeing. Most of the principles of farriery have been derived from practical experience and traditional skills of individual farriers. To date, there has been little done in the way of good science and few publications have appeared to advance the discipline. Therefore, opinions or policies on horse shoeing vary greatly between farriers and members of the veterinary profession. The aim of this workshop was to present the latest information on biomechanical analysis of horse shoeing as it relates to modern day farriery and could have direct benefits for the future of shoeing in performance horses.
Muscle adenine nucleotide degradation during submaximal treadmill exercise to fatigue. The aim was to investigate metabolic response in muscle during submaximal treadmill exercise to fatigue, with a special emphasis on adenine nucleotide degradation products such as inosine monophosphate (IMP) in muscle and hypoxanthine, xanthine and uric acid in plasma. Five Standardbred trotters performed treadmill exercise on 2 occasions, once at 7 m/s and once at 10 m/s. Venous blood samples were taken at rest, during exercise and at the end of exercise. Muscle biopsies were taken before and after exercise and muscle temperature was measured before and after exercise. Running time differed a...
Cardiac responses to training in 2-year-old thoroughbreds: an echocardiographic study. Guided M-mode echocardiography was performed in seven 2-year-old Thoroughbreds before commencement of commercial flat-race training, and 18 weeks later, when all horses were either racing regularly (5 horses), or at racing fitness (2 horses). M-mode echocardiography was performed using a 2.5 MHz annular phased array ultrasound transducer and a Vingmed 800 Supervision echocardiograph. Images were obtained from the right hemithorax; a short axis view of the left ventricle (LV) at the level of the chordae tendinae was used to position the M-mode cursor. The following variables were measured: left...
Is ventilation during maximal exercise limited by dynamic airway closure? A study was undertaken to find if the reason why horses hypoventilate when running is that they experience expiratory flow limitation due to dynamic airway closure. To test this hypothesis, we measured peak expiratory flows on a Thoroughbred galloping on a treadmill and hypoventilating and compared those flows with the peak dynamically-limited flow that the same horse could achieve during a forced expiratory flow-volume manoeuvre. At the approximate lung volumes at which the horse was ventilating while running, it did not appear to be mechanically limited and appeared to have reserve capacity ...
Factors affecting accumulation of lactate in red blood cells. In horses, both the post exercise distribution of lactate between plasma and red blood cells (RBC) and the activity of lactate transporters on the RBC membrane vary widely between individuals. In this study, we investigated the effects of pH, time and temperature on lactate distribution in vitro, and compared the in vitro activity of lactate transporters with the accumulation of lactate into RBC in vivo. To accomplish this, we took venous blood samples at rest and after trotting races. The post exercise accumulation of lactate into RBC was shown to depend on the activity of lactate transporter...
A comparison of grain, oil and beet pulp as energy sources for the exercised horse. High-grain diets for the exercising horse were compared with diets which provided 15% of the total caloric intake from either vegetable oil or a highly fermentable fibre source (beet pulp). Six Thoroughbreds age 3 years were fed one of 3 diets or 5 weeks in a replicated 3 x 3 Latin square. The CONTROL diet was 3.65 kg of sweet feed (SF), 0.9 kg of a protein/vitamin/mineral pellet and 5.45 kg of hay cubes. The FAT diet replaced 1.15 kg of SF with 0.45 kg of soybean oil and the FIBRE diet replaced 1.15 kg of SF with 1.36 kg of beet pulp. Horses were exercised 3 times per week on a high-speed tre...
Contributions of equine exercise physiology research to the success of the 1996 Equestrian Olympic Games: a review. Following public concern about the weather conditions for the 1996 Olympic Games in Atlanta an international research programme was initiated. The primary objective of this effort was to identify strategies for ensuring welfare of horses competing in the heat. Field observations of horses during the endurance test of 3-day events in Europe, Canada, and the USA characterised the work effort of this form of competition; laboratory treadmill studies assessed limitations to performance of heat and humidity, explored the relationships of thermoregulatory demands to the phases of the competition and...
Sweat production and localisation of carbonic anhydrase in the equine sweat gland during exercise at two ambient temperatures. The aim of this investigation was to study sweat production during exercise at 2 ambient temperatures (20 degrees C and 35 degrees C) and the concurrent localisation of carbonic anhydrase (CA) in the sweat gland. Horses develop alkalosis during prolonged exercise and the sweat contains HCO3-. Carbonic anhydrase is therefore of interest since it catalyses the reaction CO2 + H2OHCO3- + H+. Four standardbred trotters performed an exercise test. Skin biopsies were taken from the neck, and sweat rate, blood and skin temperatures were measured. There was a close relationship between sweat rate, temp...
The effects of training on ventilation and blood gases in exercising thoroughbreds. The effects of training on ventilation and blood gases during exercise were investigated in 6 clinically normal, detrained Thoroughbred horses. They underwent a 16 week training programme similar to the type frequently used for Thoroughbred racehorses in Great Britain. Standardized treadmill exercise tests (2 min canter at 8 and 10 m/s C8 and C10[ and 2 min gallop at 12 m/s [G12], on a level surface) were performed prior to and after 16 weeks of training. Respiratory flow rates were measured using ultrasound flow transducers. Blood samples were drawn from a transverse facial artery and the rig...
Plasma ammonia and lactate responses using incremental and constant speed exercise tests. Plasma NH3, formed during intense exercise, results principally from the deamination of AMP in muscle. Its formation during exercise may be influenced both by the pool of fibres recruited and by changes in the intracellular environment affecting ADP homeostasis. This study compared incremental and constant speed exercise as possible protocols for the investigation of plasma NH3 accumulation with intense exercise. Six trained Thoroughbred horses, one of which had recently been operated on for recurrent laryngeal neuropathy, undertook a step-wise treadmill test with 1 min incremental steps of 6,...
Ventilation-perfusion relationships during exercise in standardbred trotters with red cell hypervolaemia. In order to evaluate the pulmonary gas exchange during exercise in Standardbred trotters with red cell hypervolaemia (RCHV), 12 horses with RCHV were compared with 9 normovolaemic (NV) horses. VO2 and VCO2 were determined with an open bias flow system. Cardiovascular and haemodynamic data were recorded during exercise at 4 different speeds on a treadmill. Pulmonary gas exchange was assessed by conventional blood gas variables (arterial and mixed venous blood gas tensions), and the ventilation-perfusion distribution VA/Q was estimated by the multiple inert gas elimination technique. VA and AaDO...
Effects of frusemide on electrolyte and acid-base balance during exercise. This study was undertaken to evaluate the effects of frusemide on the concentration of plasma electrolytes and the relationship between changes in electrolyte concentration and the simultaneous changes in acid-base balance in arterial and venous blood during intense exercise. Five exercise-conditioned Thoroughbred horses were exercised on a high-speed treadmill at a slope of 10% at speeds known to exceed VO2max. Horses participated in 3 randomised exercise trials in which they received either placebo (control), low-dose frusemide (0.5 mg/kg bwt), or high-dose frusemide (1.0 mg/kg) 4 h prior to...
Blood gas changes during incremental and sprint exercise. We investigated and compared arterial blood gas and ventilatory changes during rapid acceleration sprint and during incremental treadmill exercise. Seven clinically normal racehorses completed standardised incremental exercise tests and rapid acceleration tests at speeds calculated to elicit 115% VO2max. Arterial oxygen tension decreased (P < 0.001) between 15 s (mean +/- s.d. 103.8 +/- 14.3 mmHg) and 30 s (85.0 +/- 7.7 mmHg) after the onset of rapid acceleration exercise, but did not change significantly during the remainder of the sprint. This was accompanied by an increase in PaCO2 of 5....
Chronological changes in superoxide-scavenging ability and lipid peroxide concentration of equine serum due to stress from exercise and transport. It has been suggested that a variety of stresses on animals may accelerate their production of superoxide. Racehorses are considered to be exposed to substantial oxide stress due to transport and exercise for training and racing. To determine the effect of exercise and transport on racehorses in terms of superoxide and antioxidative ability, changes in the superoxide-scavenging ability of equine serum were observed using electron spin resonance (ESR). Changes in the concentration of lipid peroxide, which is produced in equine serum by superoxide, were also examined. The analysis revealed that ...