Topic:Anaerobic Metabolism
Anaerobic metabolism in horses refers to the process by which energy is produced in the absence of oxygen, primarily during high-intensity exercise or activities that exceed the aerobic capacity. This metabolic pathway involves the breakdown of glucose to lactate through glycolysis, providing rapid energy to support short bursts of intense activity such as sprinting or jumping. While efficient for quick energy production, anaerobic metabolism results in the accumulation of lactate, which can contribute to muscle fatigue and decreased performance. Understanding anaerobic metabolism is key for optimizing training regimens, enhancing athletic performance, and preventing exercise-related disorders in horses. This page compiles peer-reviewed research studies and scholarly articles that explore the mechanisms, physiological effects, and implications of anaerobic metabolism in equine athletes.
Effect of increasing work rate on metabolic responses of the donkey (Equus asinus). Oxygen consumption (VO2) and concentration of venous blood metabolites were measured in donkeys trained to run and to pull loads on a treadmill. VO2 in two donkeys running at maximal speed on a 9.8% slope was 110 +/- 2 ml.min-1.kg-1, approximately 22 times preexercise VO2. Average heart rate at maximal VO2 (VO2max) was 223 +/- 2 beats/min, five times the preexercise heart rate. Blood lactate increased 14-fold, and blood glucose did not change (P > 0.05). Animals running up a 4% incline and incremental draft loading of five donkeys walking on the level were also studied. The total energy cost o...
Interaction of gentamycin and atracurium in anaesthetised horses. Evoked hind limb digital extensor tension (hoof twitch) was maintained at 40% of baseline for 1 h by atracurium infusion in 7 horses anaesthetised with halothane. After 1 h, atracurium was discontinued and hoof twitch allowed to recover to 75%. Atracurium was again given by infusion to maintain 40% twitch for a second hour, then 2 mg gentamycin/kg bwt were given i.v. Atracurium infusion was continued for a third hour, and then hoof twitch was again allowed to recover spontaneously to 75%. Gentamycin reduced twitch strength from 40 +/- 1% (mean +/- sem) to 29 +/- 4% within 7.0 +/- 1.5 min (P = ...
Intravenous anaesthesia in horses by guaiphenesin-ketamine-detomidine infusion: some effects. The effects of total intravenous anaesthesia with an intravenous infusion of a combination of guaiphenesin, ketamine and detomidine were studied in 10 patients scheduled for elective surgery. Anaesthesia was maintained by the infusion of guaiphenesin (100 mg/ml), ketamine (2 mg/ml) and detomidine (0.02 mg/ml). The infusion rate was 1 ml/kg/hr. During anaesthesia, pulse rate and mean arterial blood pressure were continuously recorded. Arterial blood gases and pH were determined immediately after induction and at stated times during anaesthesia. Venous blood was sampled to determine plasma gluco...
[Effect of the time of sample collection after exertion and the specimen handling on the lactate content in the blood of horses]. The mean maximal lactate concentration of horses after exercise (Lamax) amounted to 4.5 +/- 2.2 mmol/l for gallop workouts of less than 11 m/s and more than 180 s (n = 35; category A), at more than 11 m/s and less than 180 s duration (n = 17; category B) to 16.3 +/- 4.8 mmol/l and at less than 11 m/s and less than 180 s duration (n = 10; category C) to 4.6 +/- 1.6 mmol/l. Lamax was always measured immediately after exercise following exercise of categories A and C. But for exercise bouts of category B Lamax was measured between the first and the tenth minute after exercise. Following exercise ...
Training-induced modifications in cardiorespiratory and ventilatory measurements in thoroughbred horses. The effects of training and detraining on ventilation during a standardised exercise test were investigated. Ten healthy Thoroughbred horses underwent 5 standardised treadmill exercise tests (SET): SET1, at the start of the experimental period; SET2, after 3 weeks acclimatisation; SET3, after 3 week of aerobic training; SET4 after 3 weeks of anaerobic (i.e. interval) training; and SET5, after 3 weeks of detraining. The SETs were carried out in an air-conditioned laboratory on a treadmill inclined at 6 degrees. Respiratory airflow, tidal volume (VT), respiratory frequency (RF) and expired minut...
Clostridium septicum septicemia in a neonatal foal with hemorrhagic enteritis. Clostridium septicum was isolated by anaerobic culture of blood collected from a 3-day-old foal with hemorrhagic enteritis and signs suggestive of septicemia. The foal responded well to treatment with intravenous fluids, antibiotics, plasma, and oral gastrointestinal protectants. One month after apparent complete recovery from the septicemia and hemorrhagic enteritis, the foal was euthanized during an acute episode of colic that was caused by severe, strangulating intestinal adhesions, thought to have formed as a result of peritonitis secondary to the hemorrhagic enteritis. The value of anaero...
Alterations of fluid and electrolyte balance in thoroughbred racehorses following strenuous exercise during training. Alterations of acid-base status, and fluid and electrolyte balance subsequent to exercise in Thoroughbred racehorses in North America have not been well-characterized. Des-cribed here are the results of an observational study conducted to characterize changes in fluid and electrolytes following strenuous exercise of 16 Thoroughbreds under routine training conditions. Changes following strenuous exercise were determined for the following variables: serum concentrations of sodium (Na), potassium (K), chloride (Cl) and protein; pH of blood; osmolality of plasma and urine; body weight; and, fracti...
Cardiorespiratory parameters in draught horses before and after short term draught work pulling loads. In order to establish the relationship between draught force and cardiorespiratory responses to exercise heart rate (HR), respiratory rate (RR), arterial and venous blood gases, pH, hemoglobin concentration and temperature were measured in five draught horses during rest, immediately after exercise and 30 min post-exercise under field conditions. A wagon equipped with an odometer and a hydraulic dynamometer was used for measuring distance and draught force. The wagon was loaded with 946 kg for the low load, 1,979 kg for the medium load and 2,994 kg for the high load, and drawn for a distance o...
[Physical performance–a comparison between horses and men]. During heavy exercise horses can increase oxygen uptake compared to resting conditions considerably more than man. Processes involved like respiration, heart size, cardiac output, oxygen transport capacity of the blood and oxygen release in the capillaries are discussed. Besides these advantages in the aerobic metabolism conditions for the anaerobic metabolism are also more advantageous in horses than in man. The portion of fast contracting muscle fibers with little fatigue-resistance and also some of the enzymes required for the anaerobic metabolism are higher in horses.
The pharmacokinetics and locomotor activity of alfentanil in the horse. The pharmacokinetics of alfentanil were investigated in the horse. Four doses of alfentanil (4, 10, 20 and 40 micrograms/kg) were given to four horses at different times and their locomotor activity monitored. Doses of 20 and 40 micrograms/kg produced a significant increase in locomotor activity. The plasma concentrations of alfentanil were measured in six standing horses and the pharmacokinetics calculated. It was found that the decay curves were best described by a biexponential equation. The elimination half-life (t1/2 beta) was 21.65 +/- 3.99 min and the clearance (Cl) was 14.1 +/- 0.7 ml/...
Comparison of yearling, two-year-old and adult Thoroughbreds using a standardised exercise test. The purpose of this study was to compare exercise measurements in yearling, two-year-old and adult Thoroughbreds using a standardised treadmill incremental exercise test. Peak oxygen consumption (VO2 peak: 128.0 +/- 2.1, 140.0 +/- 2.1, 163.7 +/- 3.4; ml/kg/min +/- se, P less than 0.05), peak packed cell volume (PCV peak: 0.50 +/- 0.01, 0.58 +/- 0.01, 0.64 +/- 0.01 litres/litre +/- se, P less than 0.05) and the maximum number of steps completed in the exercise test (STEPmax: 7.7 +/- 0.1, 8.1 +/- 0.1, 8.6 +/- 0.1; steps +/- se, P less than 0.05) increased with age and degree of physical activity...
Aerobic and anaerobic bacterial isolates from horses with pneumonia or pleuropneumonia and antimicrobial susceptibility patterns of the aerobes. Frequency of aerobic and anaerobic isolates in 327 aspirates and in 123 pleural fluid samples from 327 horses with pneumonia or pleuropneumonia and antimicrobial susceptibility patterns of the aerobes were reported. Of the 327 horses, 75% survived, 20% were euthanatized, and 5% died. Tracheobronchial aspirates or pleural fluid specimens from 25 of the horses did not yield growth. Of the remaining 302 horses, 221 had only aerobic organisms isolated, whereas only anaerobes were isolated from 6 of the 302 horses. The remaining 75 horses had mixed aerobic and anaerobic bacterial infections. The su...
The effect of cryopreservation on the metabolic activity of day-6.5 horse embryos. The decrease in embryo viability caused by cryopreservation may be due, in part, to metabolic disturbances. To determine the effect of cryopreservation on metabolism, Day -6.5 horse embryos were either frozen and thawed using glycerol as the cryoprotectant, given only the glycerol treatment or washed an equal number of times in phosphate buffered saline (PBS). Before and after treatment, individual embryos were incubated with L-[14C(U)]-glutamine, to measure Krebs cycle activity, and D-[5-3H]-glucose, to measure Embden-Meyerhof pathway activity. Before treatment, glucose metabolism ranged from...
Diaphragm does not produce ammonia or lactate during high-intensity short-term exercise. To ascertain whether costal diaphragm engages in ammonia and lactate production (like limb muscles) during high-intensity short-term exercise, experiments were carried out on six healthy trained ponies in which phrenic venous catheters had been implanted 5-9 days earlier. Simultaneous anaerobically obtained blood samples from abdominal aorta and the phrenic vein at rest and during 4 min of exertion at 32 km/h and at a 7% grade were analyzed for blood-gas variables as well as lactate and ammonia concentrations using standard procedures. At rest, heart rate was 47 +/- 4 beats/min and the diaphra...
The stress response to anaesthesia in ponies: barbiturate anaesthesia. Information on the equine stress response to anaesthesia and surgery is sparse but offers a promising approach to elucidating the high anaesthetic risk in this species. Previous work has shown that halothane anaesthesia induces substantial metabolic and endocrine changes. This paper reports the effects of barbiturate anaesthesia. Anaesthesia was induced with thiopentone in six ponies and no further agents were given. They stood within 30 mins. On another occasion, these animals, and three further ponies, were anaesthetised with pentobarbitone and anaesthesia was maintained for 2 h. No surgery ...
Doxapram infusion during halothane anaesthesia in ponies. Doxapram, 0.05 mg/kg bodyweight/min, was infused during the second hour of 2 h halothane anaesthesia in six ponies. Two of the ponies were anaesthetised on a second occasion as controls and given 5 per cent dextrose in place of the doxapram. Respiratory depression typical of halothane anaesthesia in ponies developed in the first hour of anaesthesia and continued during the second hour in the control animals. During doxapram infusion arterial carbon dioxide tension decreased and pH increased. Arterial blood pressure increased but there was no change in pulse rate, the electrocardiogram or arter...
A comparative study of interval and conventional training in thoroughbred racehorses. Eight horses with previous racing experience were used in a comparative study of training methods for Thoroughbred racehorses. They were randomly assigned to two groups of four horses each. One group was trained using an interval training method (IT) and the other using conventional training (CT) methods. Peak heart rates, heart rate recovery curves, peak plasma lactate levels, plasma lactate clearance rates and run times were used to evaluate differences in the training methods. Peak heart rates, heart rate recovery curves, and run times were not significantly different between the groups. Ho...
Effect of show jumping on heart rate, blood lactate and other plasma biochemical values. This study investigated some physiological responses to exercise performed by a horse during show jumping. The effects of jumping on heart rate (HR), blood lactate (LA) and some other blood values were studied in nine normal horses participating at the Belgian Junior Championship. Venous blood was sampled before and immediately after the show jumping and was analysed for packed cell volume, LA, blood glucose (GLU), total plasma protein, bicarbonate, sodium, potassium (K+), chloride, calcium and activities of plasma lactate dehydrogenase, creatine phosphokinase (CK) aspartate amino transferase ...
Pulmonary shunting by the bronchial artery in the anaesthetized horse. In the quietly standing horse the bronchial arterial blood flow is low, 0.1-0.2% of the pulmonary arterial flow. In horses anaesthetized with halothane, the bronchial arterial flow is reduced by a greater fraction than that in the pulmonary artery. Thus the shunting through the bronchial circulation is decreased about 3-fold by anaesthesia, and cannot, therefore, contribute significantly to the increased alveolar-arterial gradient seen in dorsal recumbency. The results indicate bronchial vasoconstriction under anaesthesia.
Ultrasonography as a diagnostic aid in horses with anaerobic bacterial pleuropneumonia and/or pulmonary abscessation: 27 cases (1984-1986). The medical records of 83 horses with pleuropneumonia and/or pulmonary abscessation, in which thoracic sonography was used, were reviewed. The sonograms of these horses were reviewed retrospectively for free gas echoes within pleural or abscess fluid. Anaerobic infection was confirmed in 27 horses, and gas echoes were observed in 21 horses. There was a significant (P less than 0.001) correlation between the observation of gas echoes and anaerobic infection in horses with pleuropneumonia and/or pulmonary abscessation. A foul odor to the breath or pleural fluid was significantly (P less than 0.0...
Changes in the metabolic profile of the equine gluteus medius as a function of sampling depth. 1. Cross sections from the middle of the gluteus medius were removed from 10 adult horses and used to evaluate changes in histochemically determined muscle fiber type and biochemically determined metabolic enzyme activities as a function of sample depth. 2. Muscle fiber types determined using histochemical methods for myosin ATPase (pH 9.4) and succinic dehydrogenase (SDH) activity indicated percent fast-twitch glycolytic (FG) muscle fibers decreased and slow-twitch oxidative (SO) fibers increased as a function of increasing sampling depth. 3. Percent histochemically determined fast-twitch oxi...
Ultrastructural description of a new chytrid genus of caecum anaerobe, Caecomyces equi gen. nov., sp. nov., assigned to the Neocallimasticaceae. Vegetative and reproductive stages of Caecomyces equi gen. nov., sp. nov. isolated from the horse caecum were examined by light and electron microscopy. This organism, which is similar to isolates known as Sphaeromonas communis, produces uniflagellate, uninucleate zoospores whose perikinetosomal structures, i.e. circumflagellar ring, spur, struts and scoop, are similar in many respects to those described in species of Neocallimastix. Microtubular roots extend basally from the spur and associate with hydrogenosomes and the nucleus. Another group of microtubules radiates laterally in a fan-shape...
Metabolic responses to exercise in the racehorse: changes in plasma alanine concentration. Previous studies in humans have shown that alanine is released from the skeletal muscle in proportion to the work load. We have measured plasma alanine and urea concentrations in well-trained Standardbred and Finnish-bred (cold-blooded) trotters after a graded-intensity exercise and during recovery to study metabolic responses to exercise in this animal model. As controls we measured blood lactate, pyruvate, and glucose concentrations as well as hematocrit values. Metabolic responses to exercise were closely reflected in all these parameters. Plasma alanine increased relatively more than plasm...
Oxygen deficit-oxygen debt relationships in ponies during submaximal treadmill exercise. The O2 deficit-O2 debt relationship in ponies was examined at two levels of treadmill exercise. Five healthy ponies exercised for 8 min at two work rates (WR):(1) 50 m/min at 6% grade and (2) 70 m/min at 12% grade. The O2 deficit and O2 debt were calculated using open-circuit measurement of pulmonary gas exchange during the transition from rest to steady-state exercise and during recovery from exercise. The O2 deficit was significantly lower (P less than 0.05) than the O2 debt at each of the two work rates. The means (+/- SEM) for the deficit and the O2 debt, respectively, in liters were: (1) ...
Role of anaerobic bacteria in equine endometritis. This study, performed over 3 breeding seasons, surveyed anaerobic and aerobic bacterial isolates from 362 clitoral and endometrial swabs and uterine washes from 263 Thoroughbred maiden, foaling, foal heat and barren mares, and from 113 urethral, urethral fossa, preputial and pre-ejaculatory fluid swabs from 29 Thoroughbred stallions. The significance of isolates was determined by their association with acute endometritis, as determined by concurrent endometrial smear results and by consideration of age and reproductive status before and after the survey. The results suggest that the horse uter...