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Murray, J. K., Senior, J. M., & Singer, E. R. (2006). A comparison of cross-country recovery rates at CCI 2* with and without steeplechase competitions. Equine Vet J Suppl, (36), 133–138.
Abstract: REASONS FOR PERFORMING STUDY: Short format 3-day events were introduced in 2004. Anecdotal reports suggested that horses were more tired on completion of the cross-country phase of short format events when compared with horses completing the cross-country phase of long format competitions, despite the absence of Phases A, B and C. OBJECTIVES: To compare the physiological parameters and haematological parameters of horses that had completed the cross-country phase of a short format (SF) and a long format (LF) CCI 2* competition. METHODS: During a CCI 2* competition 69 competitors took part in the short format and 74 in the long format competition. Long format competitors completed Phases A, B, C and D and short format competitors completed Phase D only. Phase D (the cross-country course) was identical for both competitions. Two-way ANOVA for repeated measures and post hoc tests were used to compare temperature, pulse and respiration rates of horses competing in both types of competition. T tests were used to compare mean lactate and electrolyte concentrations, while U-Mann Whitney tests were used to compare CK and AST levels measured in horses competing in the short and long formats of the event. RESULTS: Training schedules, age and previous competition experience were not significantly different between horses competing in the SF and LF competitions. On completion of Phase D, SF horses had significantly higher PCV and significantly lower ionised calcium concentrations when compared with LF horses. LF horses had significantly higher heart rates than SF horses 10 min prior to starting Phase D and immediately after completing Phase D; however, no other significant differences were found between the 2 groups of horses. CONCLUSIONS: Only weak evidence was found to support the hypothesis that the workload for the horse in a SF CCI 2* competition is significantly different when compared to the LF CCI 2* competition. POTENTIAL RELEVANCE: There is no beneficial or detrimental effect on horses that complete short format CCI 2* competitions as compared to those that complete long format CCI 2* competitions but further research is required into the physiological response of horses at CCI 3* and CCI 4* short format competitions.
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Cattell, R. B., & Korth, B. (1973). The isolation of temperament dimensions in dogs. Behav Biol, 9(1), 15–30.
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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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Gutierrez Rincon, J. A., Vives Turco, J., Muro Martinez, I., & Casas Vaque, I. (1992). A comparative study of the metabolic effort expended by horse riders during a jumping competition. Br J Sports Med, 26(1), 33–35.
Abstract: The three main Olympic horse riding disciplines are dressage, jumping, and three-day eventing (including dressage, cross country and jumping). In the jumping discipline (obstacle race), the 'team' (horse rider) is judged under the different conditions that might take place in a varied run. The horse is expected to show power and ability; the rider must show riding skill and good physical condition. However, the different conditions encountered by the rider during competition (duration of event, continuous isometric working level, especially in the inferior trunk, lead us to consider the need for a rider to develop different metabolic pathways to meet the high energy requirements of the competition.
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Visser, E. K., Van Reenen, C. G., Rundgren, M., Zetterqvist, M., Morgan, K., & Blokhuis, H. J. (2003). Responses of horses in behavioural tests correlate with temperament assessed by riders. Equine Vet J, 35(2), 176–183.
Abstract: REASONS FOR PERFORMING STUDY: Behavioural tests as well as observers' ratings have been used to study horses' temperament. However, the relationship between the ratings and the responses in behavioural tests has not yet been studied in detail. OBJECTIVES: The aim of the present study was to examine this relationship between ratings and responses. METHODS: Eighteen mature Swedish Warmblood horses were subjected to 2 behavioural tests, one relating to novelty (novel object test) and one to handling (handling test). Subsequently, 16 of these horses were ridden by 16 equally experienced students, having no former experience with the horses. Immediately after each ride, the students scored the horse for 10 temperamental traits using a line rating method. RESULTS: It was shown that for each temperamental trait all 16 riders agreed on the ranking of the horses (0.212<W<0.505, P < 0.001). CONCLUSIONS: Correlations between behavioural and heart rate variables in the behavioural tests revealed that horses with a high level of locomotion or much restlessness behaviour exhibited high mean heart rate and low heart rate variability. In particular, heart rate variables in the behavioural tests were found to correlate with riders' rating scores. Furthermore, the underlying components of the handling test, retrieved with a principal component analysis (PCA) correlated with riders' rating scores while the underlying components of the novel object test did not. POTENTIAL CLINICAL RELEVANCE: It is concluded that it is possible for a large panel of assessors to agree upon a horse's temperament and that objective measures from behavioural tests correlate significantly with temperamental traits assessed by a panel of assessors.
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Carroll, G. L., Matthews, N. S., Hartsfield, S. M., Slater, M. R., Champney, T. H., & Erickson, S. W. (1997). The effect of detomidine and its antagonism with tolazoline on stress-related hormones, metabolites, physiologic responses, and behavior in awake ponies. Vet Surg, 26(1), 69–77.
Abstract: Six ponies were used to investigate the effect of tolazoline antagonism of detomidine on physiological responses, behavior, epinephrine, norepinephrine, cortisol, glucose, and free fatty acids in awake ponies. Each pony had a catheter inserted into a jugular vein 1 hour before beginning the study. Awake ponies were administered detomidine (0.04 mg/kg intravenously [i.v.]) followed 20 minutes later by either tolazoline (4.0 mg/kg i.v.) or saline. Blood samples were drawn from the catheter 5 minutes before detomidine administration (baseline), 5 minutes after detomidine administration, 20 minutes before detomidine administration which was immediately before the administration of tolazoline or saline (time [T] = 0), and at 5, 30, and 60 minutes after injections of tolazoline or saline (T = 5, 30, and 60 minutes, respectively). Compared with heart rate at T = 0, tolazoline antagonism increased heart rate 45% at 5 minutes. There was no difference in heart rate between treatments at 30 minutes. Blood pressure remained stable after tolazoline, while it decreased over time after saline. Compared with concentrations at T = 0, tolazoline antagonism of detomidine in awake ponies resulted in a 55% increase in cortisol at 30 minutes and a 52% increase in glucose at 5 minutes. The change in free fatty acids was different for tolazoline and saline over time. Free fatty acids decreased after detomidine administration. Free fatty acids did not change after saline administration. After tolazoline administration, free fatty acids increased transiently. Tolazoline tended to decrease sedation and analgesia at 15 and 60 minutes postantagonism. Antagonism of detomidine-induced physiological and behavioral effects with tolazoline in awake ponies that were not experiencing pain appears to precipitate a stress response as measured by cortisol, glucose, and free fatty acids. If antagonism of an alpha-agonist is contemplated, the potential effect on hormones and metabolites should be considered.
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Nicol, C. J., Adachi, M., Akiyama, T. E., & Gonzalez, F. J. (2005). PPARgamma in endothelial cells influences high fat diet-induced hypertension. Am J Hypertens, 18(4 Pt 1), 549–556.
Abstract: BACKGROUND: Peroxisome proliferator-activated receptor gamma (PPARgamma) ligands improve human hypertension. However, the mechanism and site of this effect remains unknown, confounded by PPARgamma expression in many cell types, including endothelial cells (ECs). METHODS: To evaluate the vascular role of PPARgamma we used a conditional null mouse model. Specific disruption of PPARgamma in ECs was created by crossing Tie2-Cre+ transgenic (T2T+) and PPARgamma-floxed (fl/fl) mice to generate PPARgamma (fl/fl)T2T+ (PPARgamma E-null) mice. Conscious 8- to 12-week-old congenic PPARgamma (fl/fl)Cre- (wild type) and PPARgamma E-null mice were examined for changes in systolic blood pressure (BP) and heart rate (HR), untreated, after 2 months of salt-loading (drinking water), and after treatment for 3 months with high fat (HF) diet alone or supplemented during the last 2 weeks with rosiglitazone (3 mg/kg/d). RESULTS: Untreated PPARgamma E-nulls were phenotypically indistinguishable from wild-type littermates. However, compared to similarly treated wild types, HF-treated PPARgamma E-nulls had significantly elevated systolic BP not seen after normal diet or salt-loading. Despite sex-dependent baseline differences, salt-loaded and HF-treated PPARgamma E-nulls of either sex had significantly elevated HR versus wild types. Interestingly, rosiglitazone improved serum insulin levels, but not HF diet-induced hypertension, in PPARgamma E-null mice. CONCLUSIONS: These results suggest that PPARgamma in ECs not only is an important regulator of hypertension and HR under stressed conditions mimicking those arising in type 2 diabetics, but also mediates the antihypertensive effects of rosiglitazone. These data add evidence supporting a beneficial role for PPARgamma-specific ligands in the treatment of hypertension, and suggest therapeutic strategies targeting ECs may prove useful.
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Leleu, C., & Cotrel, C. (2006). Body composition in young standardbreds in training: relationships to body condition score, physiological and locomotor variables during exercise. Equine Vet J Suppl, (36), 98–101.
Abstract: REASONS FOR PERFORMING STUDY: Body composition is an essential factor in athletic performance of human sprinters and long distance runners. However, in horses, many questions remain concerning relationships between body composition and performance in the different equine activities. OBJECTIVES: To determine relationships between body composition, body score, physiological and locomotor variables in a population of young Standardbreds in training. METHODS: Twenty-four 2-year-old Standardbreds were studied, body condition on a scale 0-5 and bodyweight recorded, and height at withers measured. Percentage of fat (%F), fat mass (FM) and fat free mass (FFM) were estimated echographically. During a standardised exercise test on the track, velocity, heart rate, respiratory frequency and blood lactate concentrations were measured. V4 and V200 (velocity for a blood lactate concentration of 4 mmol/l and velocity of 200 beats/min) calculated. Basic gait variables were measured at 3 different speeds with an accelerometric device. RESULTS: Body composition variables: %F and FM were significantly related to body condition score and physiological variables. Body score was highly correlated to %F (r = 0.64) and FM (r = 0.71). V4 was negatively correlated to %F (r = -0.59) and FM (r = -0.60), P<0.05. V200 was also negatively related to %F and FM, (r = -0.39 and r = -0.37, respectively, P<0.1). No relationships were found between body composition and gait characteristics. CONCLUSIONS: Body composition was closely related to indirect measurements of aerobic capacity, which is a major factor of athletic performance in middle distance running horses. POTENTIAL RELEVANCE: As in human athletes, trainers should take special note to evaluate optimal bodyweight and body composition of race horses to optimise performance.
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Minero, M., Canali, E., Ferrante, V., Verga, M., & Odberg, F. O. (1999). Heart rate and behavioural responses of crib-biting horses to two acute stressors. Vet. Rec., 145(15), 430–433.
Abstract: The heart rate and behaviour of 14 adult saddle horses, eight crib-biters and six normal controls, were investigated. Initially, the relationship between crib-biting and heart rate was investigated while the horses were undisturbed. The horses were tested when restrained with a lip twitch, and assessed when they were exposed suddenly to the rapid inflation of a balloon. The heart rate of the crib-biters during crib-biting was lower than during other behaviours. The crib-biters had a higher overall mean heart rate (P<0.05) suggesting that they may have had a higher basal sympathetic activity. After the application of the twitch, all the horses had a transient increase in heart rate which returned to basal values more rapidly in the crib-biters. The crib-biters were less reactive to the lip twitch, five of the six investigated remaining calm, and after the release of the twitch, they spent more time nibbling (P<0.05) than the control horses. The crib-biters reacted more strongly to the inflation of the balloon (three of the six reacted), and after it had been inflated they spent more time walking in the box.
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Sloet van Oldruitenborgh-Oosterbaan, M. M., Spierenburg, A. J., & van den Broek, E. T. W. (2006). The workload of riding-school horses during jumping.
Abstract: REASONS FOR PERFORMING THE STUDY: As there are no reports on the real workload of horses that jump fences, this study was undertaken in riding-school horses. OBJECTIVE: To compare the workload of horses jumping a course of fences with that of horses cantering over the same course at the same average speed without jumping fences. The workload variables included heart rate (HR), packed cell volume (PCV), acid-base balance (venous pH, pCO2, HCO3-) and blood lactate (LA), glucose, total protein and electrolyte concentrations. METHODS: Eight healthy riding-school horses performed test A (a course of approximately 700 m with 12 jumps from 0.8-1.0 m high at an average speed of approximately 350 m/min) and test B (same course at the same speed, but without the rails) in a crossover study with at least 4 h between the 2 tests. Before each test the horses were fitted with a heart rate meter (Polar Electro). Blood samples were taken from the jugular vein at rest prior to the test, after warm-up before starting the course, immediately after the course and after recovery. All samples were analysed immediately. RESULTS: The mean +/- s.d maximal HR (beats/min) during the course (184 +/- 17 and 156 +/- 21, respectively) and the mean HR after recovery (75 +/- 6 and 63 +/- 7, respectively) were significantly higher in test A compared to test B (P = 0.001 and P = 0.007 respectively). The mean LA concentrations after the course and after recovery (mmol/l) were significantly higher in test A (3.6 +/- 2.7 and 1.0 +/- 0.9, respectively) compared to test B (0.9 +/- 0.5 and 0.3 +/- 0.1, respectively), (P = 0.016 and P = 0.048 respectively). The mean PCV (I/l) after the course and after recovery was also significantly different between tests A (0.48 +/- 0.04 and 0.39 +/- 0.03, respectively) and B (0.42 +/- 0.04 and 0.36 +/- 0.03, respectively) (P<0.01). The mean pH and the mean HCO3- (mmol/l) after the course were significantly lower in test A (7.40 +/- 0.04 and 28.9 +/- 1.4, respectively) compared to test B (7.45 +/- 0.03 and 30.4 +/- 2.3, respectively) (P<0.05). CONCLUSIONS: This study indicates that in riding-school horses jumping fences, even at a low level competition, provokes a significant workload compared to cantering the same distance and speed without fences. POTENTIAL RELEVANCE: This study makes it clear that the extra workload of jumping fences should be taken into account in the training programmes of jumping horses. Further research with more experienced horses jumping higher fences will reveal the workload for top-level jumping horses.
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