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Grubb, T. L., Foreman, J. H., Benson, G. J., Thurmon, J. C., Tranquilli, W. J., Constable, P. D., et al. (1996). Hemodynamic effects of calcium gluconate administered to conscious horses. J Vet Intern Med, 10(6), 401–404.
Abstract: Calcium gluconate was administered to conscious horses at 3 different rates (0.1, 0.2, and 0.4 mg/kg/min for 15 minutes each). Serum calcium concentrations and parameters of cardiovascular function were evaluated. All 3 calcium administration rates caused marked increases in both ionized and total calcium concentrations, cardiac index, stroke index, and cardiac contractility (dP/dtmax). Mean arterial pressure and right atrial pressure were unchanged; heart rate decreased markedly during calcium administration. Ionized calcium concentration remained between 54% and 57% of total calcium concentration throughout the study. We conclude that calcium gluconate can safely be administered to conscious horses at 0.1 to 0.4 mg/kg/min and that administration will result in improved cardiac function.
Keywords: Animals; Blood Pressure/drug effects/physiology; Calcium/blood; Calcium Gluconate/administration & dosage/*pharmacology; Cardiac Output/drug effects/physiology; Consciousness/*physiology; Dose-Response Relationship, Drug; Female; Heart Rate/drug effects/physiology; Hemodynamic Processes/*drug effects/physiology; Horses/blood/*physiology; Infusions, Intravenous; Male; Myocardial Contraction/drug effects/physiology; Respiration/drug effects/physiology; Stroke Volume/drug effects/physiology; Time Factors
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Warren-Smith, A. K., Greetham, L., & McGreevy, P. D. (2007). Behavioral and physiological responses of horses (Equus caballus) to head lowering. Journal of Veterinary Behavior: Clinical Applications and Research, 2(3), 59–67.
Abstract: Horse trainers often report that lowering the height of a horse's head so the poll is below the height of the withers can induce a calming effect during training. Four groups of horses were used in a 2-part study to investigate the behavioral and physiological effects of head lowering in horses. In Part 1, Group A had no experimental stimuli applied and horses in Group B were trained to lower their heads when presented with a specific stimulus by the handler. The stimulus for head lowering was the application of downward pressure on the headcollar via the lead rope until the horse lowered its head such that its lips were approximately at mid-cannon (third metacarpal) height, whereupon the pressure was released. The stimulus was applied again if the horse raised its head during the 300-second test period. In Part 2, Groups C and D were aroused until their heart rates exceeded 100 beats per minute (bpm). Group C had no further experimental stimuli applied whereas Group D lowered their heads as a response to the above stimulus for a period of 300 seconds. Repeated measures analysis showed that there was no difference between the heart rate of Groups A and B or Groups C and D but that the heart rate of Groups A and B were lower than Groups C and D during the 300-second post-arousal (P < 0.001). The horses in Groups A and B were more likely to contact the handler (P < 0.001), exhibit licking and chewing (P < 0.001), rest a hindleg (P < 0.001), and sniff the ground (P < 0.001) than those in Groups C and D. The number of stimuli required to maintain the head in a lowered position was greatest during the first 30 seconds (P = 0.012 and P < 0.001, Parts 1 and 2, respectively). The current study has shown that head lowering in horses does not influence cardiac responses, even after the horses had been aroused to have their heart rates above 100 bpm. Therefore, it is not a method that will aid in calming an aroused horse in training. Contrary to popular belief, there was no association with licking-and-chewing and head lowering, nor with these behaviors and response acquisition.
Keywords: behavior; head lowering; heart rate; horse; training
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Hendriksen, P., Elmgreen, K., & Ladewig, J. (2011). Trailer-loading of horses: Is there a difference between positive and negative reinforcement concerning effectiveness and stress-related signs? J. Vet. Behav., 6(5), 261–266.
Abstract: The traditional way to train horses is by the application of negative reinforcement (NR). In the past few years, however, the use of positive reinforcement (PR) has become more common. To evaluate the effectiveness and the possible stressor effect of the 2 training methods, 12 horses showing severe trailer-loading problems were selected and exposed to trailer-loading. They were randomly assigned to one of the 2 methods. NR consisted of various degrees of pressure (lead rope pulling, whip tapping). Pressure was removed as soon as the horse complied. PR horses were exposed to clicker training and taught to follow a target into the trailer. Heart rate (HR) was recorded every 5 seconds and behavior denoting discomfort was observed using one-zero sampling with 10 seconds sampling intervals. Training was completed when the horse could enter the trailer upon a signal, or was terminated after a maximum of 15 sessions. Of the 12 horses, 10 reached the criterion within the 15 sessions. One horse was eliminated from the study because of illness and 1 PR horse failed to enter the trailer. A Mann-Whitney U-test indicated that the horses trained with NR displayed significantly more discomfort behavior per training session than horses trained with PR (NR: 13.26 ± 3.25; PR: 3.17 ± 8.93, P < 0.0001) and that horses in the PR group spent less time (second) per session to complete the training criterion (NR: 672.9 ± 247.12; PR: 539.81 ± 166.37, P < 0.01). A Mann-Whitney U-test showed that no difference existed in mean HR (bpm) between the 2 groups (NR: 53.06 ± 11.73 bpm; PR: 55.54 ± 6.7 bpm, P > 0.05), but a Wilcoxon test showed a difference in the PR group between the baseline of HR and mean HR obtained during training sessions (baseline PR: 43 ± 8.83 bpm; PR: 55.54 ± 6.7 bpm, P < 0.05). In conclusion, the PR group provided the fastest training solution and expressed less stress response. Thus, the PR procedure could provide a preferable training solution when training horses in potentially stressing situations.
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Vitale, V., Balocchi, R., Varanini, M., Sgorbini, M., Macerata, A., Sighieri, C., et al. (2013). The effects of restriction of movement on the reliability of heart rate variability measurements in the horse (Equus caballus). J. Vet. Behav., 8(5), 400–403.
Abstract: Analysis of heart rate variability (HRV) is a noninvasive approach for investigating the sympathovagal balance of the autonomic nervous system. In recent years, HRV has been increasingly evaluated in animal research. In horses, it has been suggested that basal resting conditions can be achieved by restraining them. The aim of this study was to verify how restriction of movement influences HRV i2n horses. Ten healthy standardbred mares were used to measure the electrocardiographic signal under 2 conditions: free to move in the stall and restrained in the stock. Results indicate that the restriction of movement is associated with increased nervous system sympathetic activity not consistent with resting conditions.
Keywords: behavior; heart rate variability; horse; measurement; reliability; restriction of movement
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Aureli, F., Preston, S. D., & de Waal, F. B. (1999). Heart rate responses to social interactions in free-moving rhesus macaques (Macaca mulatta): a pilot study. J Comp Psychol, 113(1), 59–65.
Abstract: Heart rate telemetry was explored as a means to access animal emotion during social interactions under naturalistic conditions. Heart rates of 2 middle-ranking adult females living in a large group of rhesus macaques (Macaca mulatta) were recorded along with their behavior. Heart rate changes during 2 types of interactions were investigated, while controlling for the effects of posture and activity. The risk of aggression associated with the approach of a dominant individual was expected to provoke anxiety in the approachee. This prediction was supported by the heart rate increase after such an approach. No increase was found when the approacher was a kin or a subordinate individual. The tension-reduction function of allogrooming was also supported. Heart rate decelerated faster during the receipt of grooming than in matched control periods.
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Harkins, J. D., Kamerling, S. G., & Church, G. (1992). Effect of competition on performance of thoroughbred racehorses. J Appl Physiol, 72(3), 836–841.
Abstract: The effect of competition and the influence of age and sex on performance were examined in a study of 18 Thoroughbred racehorses. The horses performed two solo and two competitive runs at 1,200 and 1,600 m for a total of eight runs. No group ran faster during competition, which may have been a reflection of the quality of horses used for this study and their susceptibility to stress-induced impairment of performance. Males showed no significant difference between competitive and solo run times, whereas females were consistently slower during competition. Males ran significantly faster than females in all runs. There was no difference in run times due to age, which may have been due to the high mean age (5.9 yr) of the group. The slower competitive run times may have occurred because of an earlier onset of fatigue when compared with solo runs. Plasma lactate was significantly greater for the 1,200-m competitive than for the solo runs.
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Shanahan, S. (2003). Trailer loading stress in horses: behavioral and physiological effects of nonaversive training (TTEAM). J Appl Anim Welf Sci, 6(4), 263–274.
Abstract: Resistance in the horse to trailer loading is a common source of stress and injury to horses and their handlers. The objective of this study was to determine whether nonaversive training based on the Tellington-Touch Equine Awareness Method (TTEAM; Tellington-Jones &Bruns, 1988) would decrease loading time and reduce stress during loading for horses with a history of reluctance to load. Ten horses described by their owners as “problem loaders” were subjected to pretraining and posttraining assessments of loading. Each assessment involved two 7-min loading attempts during which heart rate and saliva cortisol were measured. The training consisted of six 30-min sessions over a 2-week period during which the horse and owner participated in basic leading exercises with obstacles simulating aspects of trailering. Assessment showed heart rate and saliva cortisol increased significantly during loading as compared to baseline (p <.001 and p <.05, respectively). Reassessment after training showed a decrease in loading time (p <.02), reduced heart rate during loading (p <.002), and reduced saliva cortisol as compared to pretraining assessments. Seven “good loaders” also were subject to loading assessment for physiological comparison. Increases in heart rate during loading were significantly higher in the good loaders (p <.001). Nonaversive training simulating aspects of loading may effectively reduce loading time and stress during loading for horses with a history of resistance to trailer loading.
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Youket, R. J., Carnevale, J. M., Houpt, K. A., & Houpt, T. R. (1985). Humoral, hormonal and behavioral correlates of feeding in ponies: the effects of meal frequency. J. Anim Sci., 61(5), 1103–1110.
Abstract: The effect of meal frequency on body fluid, glucose, triiodothyronine (T3), heart rate and behavior was measured in 10 ponies. A simple reversal design was used in which each pony received one meal/day (1X) for 2 wk and six meals/day (6X) for 2 wk. The total intake/day was held constant. Feeding was followed by a rise in plasma levels of glucose, T3, protein and osmolality. One large meal was followed by significantly greater changes in all of the variables than was a meal one-sixth the size. Plasma T3 rose from 41 +/- 5 (SE) ng/liter before feeding to 43 +/- 5 ng/liter following a small meal, but rose significantly higher, from 39 +/- 4 to 60 +/- 10 ng/liter, following a large meal. Glucose rose from 84 +/- 3 to 109 +/- 7 mg/dl following a small meal and rose significantly higher, from 83 +/- 3 to 154 +/- 11 mg/dl, after a large meal. Plasma protein rose from 6.55 +/- .14 to 6.62 +/- .16 g/dl following a small meal and from 6.45 +/- .14 to 6.99 +/- .11 g/dl following a large meal. Osmolality rose from 227 +/- 1 mosmol/liter before to 279 +/- 1 mosmol/liter following a small meal and significantly higher from 278 +/- 2 to 285 +/- 1 mosnol/liter following a large meal. Heart rate rose from 42 beats/min in the absence of feed to 50 beats/min when food was visible to the ponies and did not rise higher when eating began. There were no significant differences in the cardiac response to one large meal and that to a small meal.(ABSTRACT TRUNCATED AT 250 WORDS)
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Turner, K. K., Nielsen, B. D., O'Connor, C. I., & Burton, J. L. (2006). Bee pollen product supplementation to horses in training seems to improve feed intake: A pilot study. J Anim Physiol Anim Nutr (Berl), 90(9-10), 414–420.
Abstract: The objective of this study was to determine the efficacy of supplementation of Dynamic Trio 50/50, a bee pollen-based product, to improve physical fitness, blood leukocyte profiles, and nutritional variables in exercised horses. Ten Arabian horses underwent a standardised exercise test (SET), then were pair-matched by sex and fitness and randomly assigned to BP (receiving 118 g of Dynamic Trio 50/50 daily) or CO (receiving 73 g of a placebo) for a period of 42 days. A total collection was conducted from days 18 to 21 on six geldings to determine nutrient retention and neutral detergent fibre (NDF) and acid detergent fibre (ADF) digestibility. Horses were exercise conditioned and completed another SET on day 42. V160 and V200 were calculated from SET heart rates (HR). Lactate, glucose, haematocrit (HT) and haemoglobin (HB) concentrations were determined from SET blood samples. Total leukocyte count, and circulating numbers of various leukocytes and IgG, IgM and IgA concentrations were determined in rest and recovery blood samples from both SETs. Geldings on BP (n = 3) ate more feed than CO. BP had less phosphorus excretion, and tended to retain more nitrogen. BP tended to digest more NDF and ADF while having lower NDF digestibility and tending to have lower ADF digestibility. No treatment differences existed for V160 and V200, HR, lactate, HT and HB. There was a trend for lymphocyte counts to be lower in BP than CO on day 42. Dynamic Trio 50/50 supplementation may have a positive effect on performance by helping horses in training meet their potentially increased nutrient demands by increasing feed intake and thus nutrient retention.
Keywords: *Animal Nutrition Physiology; Animals; Antibody Formation; Bees; Detergents; Dietary Fiber/metabolism; Dietary Supplements; *Digestion; Eating/*drug effects; Exercise Test/veterinary; Female; Heart Rate/drug effects/physiology; Horses/blood/immunology/*physiology; Leukocyte Count/*veterinary; Male; Oxygen Consumption/drug effects/physiology; Physical Conditioning, Animal/*physiology; Pilot Projects; *Pollen; Random Allocation
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Herder, S. L. (1989). More cardiac dressage: galop, gallop, gal(l)opitty glop. Jama, 262(3), 352.
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