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Pearce, G. P., May-Davis, S., & Greaves, D. (2005). Femoral asymmetry in the Thoroughbred racehorse. Aust Vet J, 83(6), 367–370.
Abstract: OBJECTIVE: To investigate the occurrence of geometrical asymmetries in the macro-architecture of left and right femurs from Thoroughbred racehorses previously used in competitive training and racing in New South Wales, Australia. METHODS: Detailed postmortem measurements were made of 37 characteristics of left and right femurs from eleven Thoroughbred racehorses euthanased for reasons unrelated to the study. Measurements focused on articulating surfaces and sites of attachment of muscles and ligaments known to be associated with hindlimb locomotion. RESULTS: Five measurements were significantly larger in left compared to right femurs (P < 0.05). The regions showing significant differences between left and right limbs were proximal cranial and overhead medio-lateral widths, greater trochanter depth, depth of the fovea in the femoral head and distal inter-epicondylar width. CONCLUSION: The left-right differences in femoral morphology were associated with sites of muscle and ligament attachment known to be involved with hindlimb function in negotiating turns. These differences may be the result of selection pressure for racing performance on curved race tracks and/or adaptations related to asymmetrical loading of the outside hindlimb associated with repeated negotiation of turns on such tracks.
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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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Pell, S. M., & McGreevy, P. D. (1999). Prevalence of stereotypic and other problem behaviours in thoroughbred horses. Aust Vet J, 77(10), 678–679.
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Perkins, N. R., Reid, S. W. J., & Morris, R. S. (2004). Effect of training location and time period on racehorse performance in New Zealand. 2. Multivariable analysis. N Z Vet J, 52(5), 243–249.
Abstract: AIM: To investigate training location (horses trained in Matamata vs those trained at all other venues in New Zealand), and time period (1996-1997 and 1998-1999), while controlling for other horse- and race- or trial-related factors, as a means of assessing the possible impact of construction of a new training surface at the Matamata Racing Club on indirect measures of racehorse performance (number of starts, and failure to race within 6 months of any start). METHODS: Multivariable logistic regression and poisson analysis were used to analyse data derived using a retrospective cohort approach. Multivariable logistic regression was also used to analyse a case-control study. All data were derived from New Zealand Thoroughbred Racing (NZTR), records of race and trial results for racehorses trained in Matamata and other venues in New Zealand, covering two 19-month time periods (1996- 1997 and 1998-1999). Outcome variables included whether a horse started again in the 6 months following any start that occurred in the first 13 months of either time period, and a count of the total starts for every horse. RESULTS: Factors associated with increased risk of a start being followed by a 6-month no-race period included training location other than Matamata in comparison to horses trained in Matamata in the 1996-1997 time period, increasing age, 1998- 1999 over 1996-1997, starting in a trial rather than a race, placing fourth or worse in a start, softer track conditions, summer vs autumn, increasing cumulative exercise intensity in the 60 days prior to a start, and increasing race distance. Factors associated with an increase in the total number of starts included horses trained at Matamata in 1996-1997 compared with other time period-location combinations, younger age of horses at the time of a start, longer race distance, and an increasing proportion of starts in stakes races. CONCLUSIONS: Official race and trial results data provided a valuable resource for epidemiological studies of factors influencing racehorse performance. Results of analyses performed here provided little evidence of any adverse impact of a new training surface at the Matamata Racing Club on indirect measures of racehorse performance.
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Perkins, N. R., Reid, S. W. J., & Morris, R. S. (2004). Effect of training location and time period on racehorse performance in New Zealand. 1. Descriptive analysis. N Z Vet J, 52(5), 236–242.
Abstract: AIM: To describe characteristics of Thoroughbred training stables in Matamata and in all other locations in New Zealand combined, over two 19-month time periods in 1996-1997 and 1998-1999, representing equal length periods immediately prior to and after the construction of a new training surface at the Matamata Racing Club. METHODS: Retrospective records covering all horses training and racing in New Zealand during two 19-month time periods (1996-1997 and 1998-1999), covering 161 locations, were obtained from New Zealand Thoroughbred Racing (NZTR). Outcome variables included whether a horse was raced again in the 6 months following any start in the first 13 months of either time period, number of race starts for every horse, and finishing position. Summary measures with confidence intervals (CI) and unadjusted odds ratios (OR), measuring strength of associations for various factors, were computed. RESULTS: The datasets contained information on 45,446 horses, 11,336 races, 5,110 trials and a total of 110,643 race starts. Horses trained at Matamata represented 8% (3,715) of the total horse datasets, and accounted for 11,977 race starts (10.8%). They were more likely to start in a race or trial in either time period and were 1.4 and 1.3 times as likely to finish first, second or third compared with horses trained at other locations in 1996-1997 and 1998-1999, respectively. A 6-month no-race period occurred for 9,306/12,584 (74%) horses that started at least once in the first 13 months of either time period. Horses trained at Matamata were less likely to have a 6-month no-race period than horses trained at other locations in both time periods. There was no effect of time period within each location on the probability of either a horse having a 6-month no-race period or of a race start being followed by a 6-month no-race period, but there was an overall effect of time and more 6-month no-race periods were observed in 1998-1999 relative to 1996-1997. CONCLUSION: Summary statistics are presented for Thoroughbred racing in New Zealand over two 19-month time periods. Differences between the populations of horses trained in Matamata compared with those trained at other locations were attributed, in part, to the fact that many of the more successful racehorse trainers in the country have stables at Matamata. As a result, the population of horses in Matamata may not be representative of the racehorse population in New Zealand. Although more likely to win or place in both time periods, the magnitude of the advantage to horses in Matamata was reduced in 1998-1999 relative to 1996-1997, and this could be due, in part, to effects of the new track surface at Matamata. There was no evidence of a rise in risk of a 6-month no-race period following any race start in those horses trained in Matamata in 1998-1999 relative to either horses trained at other locations or to horses trained in Matamata during the earlier time period.
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Pinchbeck, G. L., Clegg, P. D., Proudman, C. J., Morgan, K. L., & French, N. P. (2004). A prospective cohort study to investigate risk factors for horse falls in UK hurdle and steeplechase racing. Equine Vet J, 36(7), 595–601.
Abstract: REASONS FOR PERFORMING STUDY: Equine fatalities during racing continue to be a major welfare concern and falls at fences are responsible for a proportion of all equine fatalities recorded on racecourses. OBJECTIVES: To identify and quantify risk factors for horse falls in National Hunt (NH) racing and to report the frequency of falling and falling-associated fatalities. METHODS: A prospective cohort study was conducted on 2879 horse starts in hurdle and steeplechase races on 6 UK racecourses. Any horse that suffered a fall at a steeplechase or hurdle fence during the race was defined as a case. Data were obtained by interview and observations in the parade ring and from commercial databases. Multivariable logistic regression models, allowing for clustering at the level of the track, were used to identify the relationship between variables and the risk of falling. RESULTS: There were 124 falling cases (32 in hurdling and 92 in steeplechasing) identified. The injury risk of fallers was 8.9% and fatality risk 6.5%. Duration of journey to the racecourse, behaviour in the parade ring and weather at the time of the race were associated with falling in both hurdle and steeplechase racing. Age, amount of rainfall and going were also associated with falling in steeplechase racing. CONCLUSIONS: Falls at fences are significant contributors to equine fatalities during NH racing. Potentially modifiable risk factors identified were the condition of track surfaces and journey time to the racecourse. POTENTIAL RELEVANCE: It is hoped that information from this study may be used in future interventions to improve horse and jockey safety in racing. The study has also identified areas requiring further research, such as equine behaviour and its effect on racing performance, and the effect of light conditions on jumping ability.
Keywords: *Accidental Falls/mortality/statistics & numerical data; Age Factors; Animal Welfare; Animals; Athletic Injuries/epidemiology/etiology/mortality/*veterinary; Cohort Studies; Great Britain; Horses/*injuries; Logistic Models; Odds Ratio; Prospective Studies; Questionnaires; Rain; Risk Factors; Safety; Sports
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Pinchbeck, G. L., Clegg, P. D., Proudman, C. J., Morgan, K. L., & French, N. R. (2004). Whip use and race progress are associated with horse falls in hurdle and steeplechase racing in the UK. Equine Vet J, 36(5), 384–389.
Abstract: REASONS FOR PERFORMING STUDY: Falls during racing present a risk of injury to both horse and jockey and a risk of fatality to horses. OBJECTIVES: To use video recordings of races to describe the circumstances surrounding horse falls at hurdle and steeplechase fences and to identify and quantify within-race risk factors for horse falls in National Hunt racing in the UK. METHODS: A retrospective, matched, nested case-control study using video recordings of races was conducted on 6 UK racecourses. Cases and controls were matched on both race type and jump number at which the fall occurred. Conditional logistic regression analysis was used to examine the univariable and multivariable relationship between predictor variables and the risk of falling. RESULTS: The risk of falling was significantly associated with whip use and race progress. Horses which were being whipped and progressing through the race were at greater than 7 times the risk of falling compared to horses which were not being whipped and which had no change in position or lost position through the field. CONCLUSIONS: This study has identified whip use and the position of the horse with respect to others in the field as potential risk factors for horse falls. POTENTIAL RELEVANCE: If these findings are confirmed by the use of intervention trials (e.g. with whip-free or restricted whip use races), modifications could be introduced which would reduce the frequency of horse falls, leading to improved equine welfare.
Keywords: Accidental Falls/*statistics & numerical data; Animals; Athletic Injuries/epidemiology/etiology/*veterinary; Case-Control Studies; Cohort Studies; Great Britain/epidemiology; Horses/*injuries; Logistic Models; Odds Ratio; Retrospective Studies; Risk Factors; Running/statistics & numerical data; Sports; Videotape Recording
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Pritchard, J. C., Barr, A. R. S., & Whay, H. R. (2006). Validity of a behavioural measure of heat stress and a skin tent test for dehydration in working horses and donkeys (Vol. 38).
Abstract: REASONS FOR PERFORMING STUDY: Dehydration and heat stress are serious welfare issues for equids working in developing countries. There is a lack of any standardised method or validated interpretation of the skin tent test in horses and donkeys. Owners of dehydrated and heat-stressed animals often depend on veterinary examination for identification of these conditions, leading to delays in treatment and unnecessary reliance on external sources to effect welfare improvement. OBJECTIVES: To validate a standardised skin tent test for dehydration and a behavioural measure of heat stress in working equids; and to examine the effect of heat stress and dehydration on tripping and staggering behaviour. METHODS: The study was carried out on 130 working horses and donkeys in Pakistan. Associations between skin tent and blood parameters (packed cell volume [PCV], serum total protein [TP], serum osmolality), clinical parameters, resting and drinking behaviour were examined. Heat stress behaviour (increased respiratory rate and depth, head nodding, flared nostrils, apathy) was observed in conjunction with rectal temperature. Tripping and staggering were assessed using a simple obstacle course. RESULTS: In both species, heat stress behaviour was significantly associated with increased rectal temperature (P<0.001). A positive skin tent test was not significantly associated with PCV or TP, although in donkeys it was significantly associated with lower serum osmolality (P<0.001). More animals age >15 years had a positive skin tent than those in younger age groups (P = 0.037). Very thin horses were more likely to have a positive skin tent than those in thin or moderate condition (P = 0.028). There was no significant correlation between skin tent and tripping or staggering in either species. CONCLUSIONS AND POTENTIAL RELEVANCE: Heat stress behaviour is related to increased body temperature in working horses and donkeys. Owners may use this to make judgements regarding rest and cooling, precluding the need to seek veterinary attention. The skin tent test for dehydration used in this study did not show a significant relationship with PCV or TP. However, the use of blood parameters to validate the skin tent test may be confounded by anaemia, hypoproteinaemia or electrolyte depletion. Alternative methods are needed to confirm or refute the validity of the skin tent test in working equids.
Keywords: Age Factors; Animal Welfare; Animals; Behavior, Animal/physiology; Body Temperature/*physiology; Body Weight/physiology; Case-Control Studies; Dehydration/diagnosis/pathology/*veterinary; Drinking; *Equidae; Female; Heat Stress Disorders/diagnosis/physiopathology/*veterinary; Horse Diseases/*diagnosis/pathology; Horses; Hypovolemia/diagnosis/physiopathology/veterinary; Male; Osmolar Concentration; Pakistan; Respiration; Skin/*pathology; Species Specificity; Work
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Quiroz-Rothe, E., Novales, M., Aguilera-Tejero, E., & Rivero, J. L. L. (2002). Polysaccharide storage myopathy in the M. longissimus lumborum of showjumpers and dressage horses with back pain. Equine Vet J, 34(2), 171–176.
Abstract: This study was designed to investigate whether horses with clinical signs of back pain due to suspected soft tissue injuries were affected by polysaccharide storage myopathy (PSSM). Diagnosis of PSSM in muscle biopsies obtained from the M. longissimus lumborum of 5 showjumpers and 4 dressage horses with a history of back pain is reported. M. longissimus lumborum biopsies of these horses were characterised histopathologically and in 3/9 cases also by electron microscopy. Observations were compared with M. gluteus biopsies of the same horses, and with M. gluteus biopsies obtained from 6 Standardbreds with recurrent exertional rhabdomyolysis and from 6 healthy trotters. M. longissimus biopsies from horses with back pain showed pathognomonic signs of PSSM, i.e. high glycogen and/or abnormal complex amylase-resistant polysaccharide deposits. Similar features were found in M. gluteus biopsies of the same horses. Sections of horses with rhabdomyolysis had increased PAS stain when compared with healthy horses, but did not show amylase-resistant material. Qualitative observations were corroborated by quantitative histochemistry (optical densities) of sections stained with PAS and amylase PAS. This study demonstrated the presence of PSSM in the M. longissimus of showjumpers and dressage horses with back pain and indicates that epaxial muscle biopsy is an option in diagnosing back problems in horses when clinical examination and imaging techniques do not provide a precise diagnosis.
Keywords: Amylases/analysis; Animals; Back Pain/etiology/*veterinary; Biopsy; Carbohydrate Metabolism, Inborn Errors/diagnosis/pathology/*veterinary; Diagnosis, Differential; Glycogen/analysis; Horse Diseases/*diagnosis/pathology; Horses; Microscopy, Electron; Muscle, Skeletal/pathology; Muscular Diseases/diagnosis/pathology/*veterinary; Polysaccharides/*metabolism; Rhabdomyolysis/diagnosis/pathology/veterinary
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Rhodin, M., Johnston, C., Holm, K. R., Wennerstrand, J., & Drevemo, S. (2005). The influence of head and neck position on kinematics of the back in riding horses at the walk and trot. Equine Vet J, 37(1), 7–11.
Abstract: REASONS FOR PERFORMING STUDY: A common opinion among riders and in the literature is that the positioning of the head and neck influences the back of the horse, but this has not yet been measured objectively. OBJECTIVES: To evaluate the effect of head and neck position on the kinematics of the back in riding horses. METHODS: Eight Warmblood riding horses in regular work were studied on a treadmill at walk and trot with the head and neck in 3 different predetermined positions achieved by side reins attached to the bit and to an anticast roller. The 3-dimensional movement of the thoracolumbar spine was measured from the position of skin-fixed markers recorded by infrared videocameras. RESULTS: Head and neck position influenced the movements of the back, especially at the walk. When the head was fixed in a high position at the walk, the flexion-extension movement and lateral bending of the lumbar back, as well as the axial rotation, were significantly reduced when compared to movements with the head free or in a low position. At walk, head and neck position also significantly influenced stride length, which was shortest with the head in a high position. At trot, the stride length was independent of head position. CONCLUSIONS: Restricting and restraining the position and movement of the head and neck alters the movement of the back and stride characteristics. With the head and neck in a high position stride length and flexion and extension of the caudal back were significantly reduced. POTENTIAL RELEVANCE: Use of side reins in training and rehabilitation programmes should be used with an understanding of the possible effects on the horse's back.
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