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Miller, R. M. (2000). The revolution in horsemanship. J Am Vet Med Assoc, 216(8), 1232–1233.
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Young, L. E., Rogers, K., & Wood, J. L. N. (2005). Left ventricular size and systolic function in Thoroughbred racehorses and their relationships to race performance. J Appl Physiol, 99(4), 1278–1285.
Abstract: Cardiac morphology in human athletes is known to differ, depending on the sports-specific endurance component of their events, whereas anecdotes abound about superlative athletes with large hearts. As the heart determines stroke volume and maximum O(2) uptake in mammals, we undertook a study to test the hypothesis that the morphology of the equine heart would differ between trained horses, depending on race type, and that left ventricular size would be greatest in elite performers. Echocardiography was performed in 482 race-fit Thoroughbreds engaged in either flat (1,000-2,500 m) or jump racing (3,200-6,400 m). Body weight and sex-adjusted measures of left ventricular size were largest in horses engaged in jump racing over fixed fences, compared with horses running shorter distances on the flat (range 8-16%). The observed differences in cardiac morphologies suggest that subtle differences in training and competition result in cardiac adaptations that are appropriate to the endurance component of the horses' event. Derived left ventricular mass was strongly associated with published rating (quality) in horses racing over longer distances in jump races (P < or = 0.001), but less so for horses in flat races. Rather, left ventricular ejection fraction and left ventricular mass combined were positively associated with race rating in older flat racehorses running over sprint (<1,408 m) and longer distances (>1,408 m), explaining 25-35% of overall variation in performance, as well as being closely associated with performance in longer races over jumps (23%). These data provide the first direct evidence that cardiac size influences athletic performance in a group of mammalian running athletes.
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Henderson, A. J. Z. (2007). Don't fence me in: managing psychological well being for elite performance horses. J. Appl. Anim. Welf. Sci., 10(4), 309–329.
Abstract: This article posits that stereotypical behavior patterns and the overall psychological well being of today's performance horse could be substantially enhanced with care that acknowledges the relationship between domesticated horses and their forerunners. Feral horses typically roam in stable, social groups over large grazing territories, spending 16-20 hr per day foraging on mid- to poor-quality roughage. In contrast, today's elite show horses live in relatively small stalls, eat a limited-but rich-diet at specific feedings, and typically live in social isolation. Although the horse has been domesticated for more than 6000 years, there has been no selection for an equid who no longer requires an outlet for these natural behaviors. Using equine stereotypies as a welfare indicator, this researcher proposes that the psychological well being of today's performance horse is compromised. Furthermore, the article illustrates how minimal management changes can enhance horses' well being while still remaining compatible with the requirements of the sport-horse industry. The article discusses conclusions in terms of Fraser, Weary, Pajor, and Milligan's “integrative welfare model” (1997).
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Jablonska, E. M., Ziolkowska, S. M., Gill, J., Szykula, R., & Faff, J. (1991). Changes in some haematological and metabolic indices in young horses during the first year of jump-training. Equine Vet J, 23(4), 309–311.
Abstract: Effects of an 18 min exercise test, on three separate occasions during a one year jump-training programme, was studied in seven horses. Determinations were carried out on venous blood for packed cell volume, haemoglobin, total protein, lactate and pyruvate, glucose, free fatty acids, insulin, glucagon, blood gases, bicarbonate, pH, aldolase, aspartate aminotransferase and alanine amino-transferase. Exercise caused a slight increase in lactate and pyruvate, total protein, aldolase, alanine aminotransferase, pO2, bicarbonate and pH. Glucose, free fatty acids and pCO2 levels decreased. Training caused no significant difference in these changes. However, during the year, increases in lactate and decreases in pH (resting levels) were observed.
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Clayton, H. M. (1993). Development of conditioning programs for dressage horses based on time-motion analysis of competitions. J Appl Physiol, 74(5), 2325–2329.
Abstract: The time-motion characteristics of Canadian basic- and medium-level dressage competitions are described, and the results are applied in formulating sport-specific conditioning programs. One competition was analyzed at the six levels from basic 1 to medium 3. Each test was divided into a series of sequences based on the type and speed of activity. The durations of the sequences were measured from videotapes. The basic-level tests had fewer sequences, and they were shorter in distance and duration than the medium tests (P < 0.10), but the average speed did not differ between the two levels. It is recommended that horses competing at the basic levels be conditioned using 5-min exercise periods, with short (10-s) bursts of lengthened trot and canter included at basic 2 and above. In preparation for medium-level competitions, the duration of the work periods increases to 7 min, 10- to 12-s bursts of medium or extended trot and canter are included, and transitions are performed frequently to simulate the energy expenditure in overcoming inertia.
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Clayton, H. M. (1993). The extended canter: a comparison of some kinematic variables in horses trained for dressage and for racing. Acta Anat (Basel), 146(2-3), 183–187.
Abstract: This study was designed to test the hypothesis that there is no significant difference in selected temporal and linear stride variables of the extended canter in horses bred and trained for dressage or racing. Nine advanced-level dressage horses and 7 Thoroughbred racehorses were filmed at a frame rate of 200 Hz at an extended canter on a sand track. Two strides were recorded per trial, and each horse performed 6 or 7 trials. Temporal and linear data were determined from the films, and descriptive statistics (mean, SD) were calculated. Strides were selected for analysis on the basis of having a velocity in the range of 6.0-7.0 m/s, and multivariate analysis of variance was used to detect significant differences in the stride kinematics of horses trained for the two sports (p < or = 0.01). The average velocity of the dressage horses was 6.37 m/s, compared with 6.40 m/s for the racehorses. There were no significant differences between the two groups in velocity, stride duration, stride length or the distances between limb placements. The stance durations of all four limbs and the overlaps between them were longer, whereas the duration of the suspension phase was shorter in the dressage horses than in the racehorses (p < or = 0.01). The time between impacts of the diagonal limb pair was close to zero in both groups, with individual horses showing some variability in the order of placement of the diagonal limb pair. However, the sequence of footfalls was not significantly different between the two groups (p < or = 0.01).
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Winkelmayr, B., Peham, C., Fruhwirth, B., Licka, T., & Scheidl, M. (2006). Evaluation of the force acting on the back of the horse with an English saddle and a side saddle at walk, trot and canter. Equine Vet J Suppl, (36), 406–410.
Abstract: REASONS FOR PERFORMING STUDY: Force transmission under an English saddle (ES) at walk, trot and canter is commonly evaluated, but the influence of a side saddle (SS) on the equine back has not been documented. HYPOTHESIS: Force transmission under a SS, with its asymmetric construction, is different from an ES in walk, trot and canter, expressed in maximum overall force (MOF), force in the quarters of the saddle mat, and centre of pressure (COP). The biomechanics of the equine back are different under a SS compared to ES. METHODS: Thirteen horses without clinical signs of back pain ridden in an indoor riding school with both saddles were measured using an electronic saddle sensor pad. Synchronous kinematic measurements were carried out with tracing markers placed along the back in front of (withers, W) and behind the saddle (4th lumbar vertebra, L4). At least 6 motion cycles at walk, trot and canter with both saddles (ES, SS) were measured. Out of the pressure distribution the maximum overall force (MOF) and the location of the centre of pressure (COP) were calculated. RESULTS: Under the SS the centre of pressure was located to the right of the median and slightly caudal compared to the COP under the ES in all gaits. The MOF was significantly different (P<0.01) between saddles. At walk, L4 showed significantly larger (P<0.01) vertical excursions under the ES. Under the SS relative horizontal movement of W was significantly reduced (P<0.01) at trot, and at canter the transversal movement was significantly reduced (P<0.01) . In both trot and canter, no significant differences in the movement of L4 were documented. CONCLUSIONS AND POTENTIAL RELEVANCE: The results demonstrate that the load under a SS creates asymmetric force transmission under the saddle, and also influences back movement. To change the load distribution on the back of horses with potential back pain and as a training variation, a combination of both riding styles is suitable.
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Krzak, W. E., Gonyou, H. W., & Lawrence, L. M. (1991). Wood chewing by stabled horses: diurnal pattern and effects of exercise. J. Anim Sci., 69(3), 1053–1058.
Abstract: Nine yearling horses, stabled in individual stalls, were used in a trial to determine the diurnal pattern of wood chewing and the effects of exercise on this behavior. The trial was a Latin square design conducted over three 2-wk periods during which each horse was exposed to each of the three following treatments: 1) no exercise (NE), 2) exercise after the morning feeding (AM), and 3) exercise in the afternoon (PM). Horses were fed a complete pelleted feed in the morning and both pelleted feed and long-stemmed hay in the afternoon. Exercise consisted of 45 min on a mechanical walker followed by 45 min in a paddock with bare soil. Each stall was equipped with two untreated spruce boards during each period for wood chewing. Wood chewing was evaluated by videotaping each horse for 22 h during each period, determining the weight and volume of the boards before and after each period, and by visual appraisal of the boards. Intake of trace mineralized salt was also measured. Wood chewing occurred primarily between 2200 and 1200. All measures of wood chewing were correlated when totals for the entire 6 wk were analyzed. When analysis was performed on 2-wk values, videotape results were not correlated with volume or weight loss of boards. Horses chewed more when on the NE treatment (511 s/d) than when on AM or PM (57 and 136 s/d, respectively; P less than .05). Salt intake tended to be greater for NE than for the other treatments (P less than .10).(ABSTRACT TRUNCATED AT 250 WORDS)
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Kasashima, Y., Takahashi, T., Smith, R. K. W., Goodship, A. E., Kuwano, A., Ueno, T., et al. (2004). Prevalence of superficial digital flexor tendonitis and suspensory desmitis in Japanese Thoroughbred flat racehorses in 1999. Equine Vet J, 36(4), 346–350.
Abstract: REASONS FOR PERFORMING STUDY: Overstrain injuries to the superficial digital flexor tendon (SDFT) and suspensory ligament (SI) are among the most common musculoskeletal injuries which contribute to the considerable wastage of racing Thoroughbreds. Many epidemiological studies have demonstrated the prevalence of and risk factors for tendon injury when racing but have not included those injuries sustained during training. However, since tendon injury during training is seen commonly in clinical practice, it is appropriate to determine the overall prevalence of tendon injury sustained during both training and racing. OBJECTIVE: To determine the prevalence of overstrain injury to the SDFT and SL during training and racing among Thoroughbred flat racehorses in Japan in 1999. METHODS: A retrospective study was performed using a sample population of 10,262 Thoroughbred racehorses. The medical information database of Thoroughbred racehorses registered by the Japan Racing Association (JRA) in 1999 was analysed for SDFT and SL overstrain injury diagnosed by a veterinarian employed by JRA during training and racing. Jump racehorses were excluded from this study. RESULTS: The prevalence of forelimb SDFT tendonitis and SL desmitis was 11.1% (1130 cases) and 3.61% (370 cases) of the population, respectively. In the hindlimb, there were 0.06% (6 cases) and 0.14% (14 cases), respectively. Risks of SDF tendonitis in the forelimb in 3-year-olds or older horses were significantly higher than in 2-year-olds. In contrast, the risk of SL desmitis in the forelimb at age 3 and 4 years was 2.23 and 2.11 times higher, respectively, than in 2-year-olds, but this increased to 5.07 times in those age > or = 5 years. Entire males were at greater risk in comparison to females and geldings. CONCLUSIONS: The results suggest that the prevalence of SDF tendonitis and SL desmitis in the forelimb was associated with the horse's age and sex. The prevalence of SL desmitis increased further with age compared with SDF tendonitis, possibly reflecting a more rapid accumulation of degeneration in this structure. POTENTIAL RELEVANCE: The age-related risk demonstrated in this study provides further support that overstrain injuries are associated with accumulated degeneration. These data provide a valuable resource for further research into the aetiology of tendon injury in the racehorse.
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Peel, J. A., Peel, M. B., & Davies, H. M. S. (2006). The effect of gallop training on hoof angle in thoroughbred racehorses. Equine Vet J Suppl, (36), 431–434.
Abstract: REASONS FOR PERFORMING STUDY: The economic impact of soundness problems in racehorses is very high and low hoof angle at the toe has been associated with a lack of soundness. However, it is not clear what environmental and management factors might contribute to a low hoof angle. OBJECTIVES: To investigate the hypothesis that the hooves of racehorses become flatter when in gallop training, as well as to determine factors contributing to this trend. METHODS: Weekly hoof measurements were taken with a hoof gauge from 45 Thoroughbred racehorses; 4 Thoroughbred show horses kept in consistent conditions and shod by the same farrier as some of the racehorses; and 6 unshod free-ranging horses. A further 15 horses were measured twice in one day to determine the repeatability of the method. RESULTS: Repeatability coefficients were 0.31 degrees for the left hoof and 0.37 degrees for the right. Racehorses in training showed a significant decrease in hoof angle over time while free ranging horses and show horses did not. Free-ranging horses had a significantly lower angle in winter (wet) compared with summer (dry) in both left (P = 0.040) and right (P = 0.017). Show horses had no significant change in hoof angle. Racehorses that had a period of rest during the experiment (n = 11) showed a decrease in hoof angle during training and an increase over their rest period for both hooves (P = 0.005 for the left hoof, P = 0.0009 for the right). CONCLUSIONS: Training for fast exercise in Thoroughbred racehorses is associated with a reduction in hoof angle and wet pasture conditions may also be associated with a reduced hoof angle in free-ranging horses. Potential relevance: Gallop exercise has a potentially large effect on hoof angle and therefore, a change in angle should be expected to occur in racehorses starting fast exercise work. Hence management of horses with abnormally low hoof angles may require an adaptation to their training regime in order to minimise this effect.
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