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Susan M. Stover - One of the best experts on this subject based on the ideXlab platform.
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Caudal lumbar vertebral fractures in California Quarter Horse and Thoroughbred raceHorses.
Equine Veterinary Journal, 2014Co-Authors: E. M. Collar, Peta L Hitchens, Mathieu Spriet, Regina Zavodovskaya, T. Wisner, Francisco A. Uzal, Susan M. StoverAbstract:Summary Reasons for performing study To gain insight into the pathophysiology of equine lumbar vertebral fractures in raceHorses. Objectives To characterise equine lumbar vertebral fractures in California raceHorses. Study design Retrospective case series and prospective case–control study. Methods RaceHorse post mortem reports and jockey injury reports were retrospectively reviewed. Vertebral specimens from 6 raceHorses affected with lumbar vertebral fractures and 4 control raceHorses subjected to euthanasia for nonspinal fracture were assessed using visual, radiographic, computed tomography and histological examinations. Results Lumbar vertebral fractures occurred in 38 Quarter Horse and 29 Thoroughbred raceHorses over a 22 year period, primarily involving the 5th and/or 6th lumbar vertebrae (L5–L6; 87% of Quarter Horses and 48% of Thoroughbreds). Lumbar vertebral fractures were the third most common musculoskeletal cause of death in Quarter Horses and frequently involved a jockey injury. Lumbar vertebral specimens contained anatomical variations in the number of vertebrae, dorsal spinous processes and intertransverse articulations. Lumbar vertebral fractures examined in 6 raceHorse specimens (5 Quarter Horses and one Thoroughbred) coursed obliquely in a cranioventral to caudodorsal direction across the adjacent L5–L6 vertebral endplates and intervertebral disc, although one case involved only one endplate. All cases had evidence of abnormalities on the ventral aspect of the vertebral bodies consistent with pre-existing, maladaptive pathology. Conclusions Lumbar vertebral fractures occur in raceHorses with pre-existing pathology at the L5–L6 vertebral junction that is likely predisposes Horses to catastrophic fracture. Knowledge of these findings should encourage assessment of the lumbar vertebrae, therefore increasing detection of mild vertebral injuries and preventing catastrophic raceHorse and associated jockey injuries.
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Jockey Falls, Injuries, and Fatalities Associated With Thoroughbred and Quarter Horse Racing in California, 2007-2011.
Orthopaedic journal of sports medicine, 2013Co-Authors: Peta L Hitchens, Ashley E. Hill, Susan M. StoverAbstract:Despite the popularity of the Horse racing industry in the United States and the wide recognition that Horse racing is one of the most hazardous occupations, little focused research into the prevention of falls by and injuries to jockeys has been conducted. To describe the incidence rates and characteristics of falls and injuries to Thoroughbred and Quarter Horse racing jockeys in the state of California. Descriptive epidemiology study. Data on race-day falls and injuries were extracted from jockey accident reports submitted to the California Horse Racing Board from January 2007 to December 2011. Denominator data, number of jockey race rides, were obtained from commercial and industry databases. Jockey fall, injury, and fatality incidence rates and ratios in Thoroughbred and Quarter Horse flat races were estimated using Poisson regression. Characteristics of falls and injuries are described and compared. In Thoroughbred races, 184 jockey injuries occurred from 360 reported jockey falls, 180,646 race rides, 23,500 races, and 3350 race meetings. In Quarter Horse races, 85 jockey injuries occurred from 145 jockey falls, 46,106 race rides, 6320 races, and 1053 race meetings. Jockey falls occurred at a rate of 1.99 falls per 1000 rides in Thoroughbred races, with 51% of falls resulting in jockey injury, and 3.14 falls per 1000 rides in Quarter Horse races, with 59% of falls resulting in jockey injury. The majority of falls occurred during a race, with catastrophic injury or sudden death of the Horse reported as the most common cause in both Thoroughbred (29%) and Quarter Horse (44%) races. During the period studied, 1 jockey fatality resulted from a fall. Jockey fall rates were lower but injury rates were comparable to those reported internationally. On average, a licensed jockey in California can expect to have a fall every 502 rides in Thoroughbred races and every 318 rides in Quarter Horse races. While jockey fall rates were lower, injury rates were similar to those in other racing jurisdictions. The high proportion of jockey falls caused by Horse fatalities should be further investigated.
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jockey falls injuries and fatalities associated with thoroughbred and Quarter Horse racing in california 2007 2011
Orthopaedic Journal of Sports Medicine, 2013Co-Authors: Peta L Hitchens, Ashley E. Hill, Susan M. StoverAbstract:Background:Despite the popularity of the Horse racing industry in the United States and the wide recognition that Horse racing is one of the most hazardous occupations, little focused research into the prevention of falls by and injuries to jockeys has been conducted.Purpose:To describe the incidence rates and characteristics of falls and injuries to Thoroughbred and Quarter Horse racing jockeys in the state of California.Study Design:Descriptive epidemiology study.Methods:Data on race-day falls and injuries were extracted from jockey accident reports submitted to the California Horse Racing Board from January 2007 to December 2011. Denominator data, number of jockey race rides, were obtained from commercial and industry databases. Jockey fall, injury, and fatality incidence rates and ratios in Thoroughbred and Quarter Horse flat races were estimated using Poisson regression. Characteristics of falls and injuries are described and compared.Results:In Thoroughbred races, 184 jockey injuries occurred from 3...
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case control study of high speed exercise history of thoroughbred and Quarter Horse raceHorses that died related to a complete scapular fracture
Equine Veterinary Journal, 2013Co-Authors: S A Vallance, Peta L Hitchens, Rachel Entwistle, Ian A Gardner, Susan M. StoverAbstract:Summary Reasons for performing study: Identification of exercise history patterns that are related to catastrophic scapular fracture will facilitate prevention of raceHorse fatalities. Objectives: To determine if exercise patterns are associated with scapular fracture in Thoroughbred (TB) and Quarter Horse (QH) raceHorses. Methods: High-speed exercise histories for 65 TB and 26 QH raceHorses that had a complete scapular fracture (cases) and 2 matched control raceHorses were retrospectively studied. Exercise variables were created from lifetime race and official timed workout reports. Associations between exercise variables and scapular fracture were investigated using conditional logistic regression. Results: Thoroughbreds with a scapular fracture had a greater number of workouts, events (combined works and races), and mean event distances than QHs with a scapular fracture. Quarter Horses worked less frequently and accumulated distance at a lower rate than TBs. Breed differences were not found for career race number or length, time between races or lay-up variables for Horses with ≥1 lay-up. For both breeds, cases had fewer events, lower recent accumulated distance and fewer active days in training than controls; however, a subset of TB cases with >10 events since lay-up had a longer active career than controls. For QHs that had a lay-up, total and mean lay-up times were greater for cases than controls. Multivariable models revealed that odds ratios (OR) of scapular fracture were greater for TBs that had not yet raced (OR = 23.19; 95% confidence interval (CI) 3.03–177.38) and lower for QHs with more events (OR = 0.71; 95% CI 0.54–0.94). Conclusions and clinical relevance: RaceHorses that are in early high-speed training but behind that of their training cohort should be examined for signs of scapular stress remodelling. Quarter Horses that had a prolonged lay-up and TBs that have endured high-speed training for a longer duration than that of their training cohort also were at greater risk.
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Fatal musculoskeletal injuries of Quarter Horse raceHorses: 314 cases (1990-2007).
Javma-journal of The American Veterinary Medical Association, 2012Co-Authors: Tiffany L. Sarrafian, Hailu Kinde, Francisco A. Uzal, Janet Moore, James T Case, B. M. Daft, Deryck H. Read, Susan M. StoverAbstract:Objective—To determine major causes of death and the anatomic location of musculoskeletal injuries in Quarter Horse raceHorses in California. Design—Retrospective case series. Animals—314 Quarter Horse raceHorses with musculoskeletal injuries that were necropsied through the California Horse Racing Board Postmortem Program from 1990 to 2007. Procedures—Postmortem pathology reports were retrospectively reviewed. Musculoskeletal injuries were categorized by anatomic region and described. The number of Quarter Horse starts and starters for the same period of time were obtained from a commercial database for determination of fatal injury incidence. Results—Musculoskeletal injuries accounted for 314 of the 443 (71 %) Quarter Horse raceHorses that died during the 18-year study period. Fatal musculoskeletal injuries occurred at a rate of 2.0 deaths/1,000 race starts and 18.6 deaths/1,000 Horses that started a race. Musculoskeletal injuries occurred predominantly during racing (84%) and in the forelimbs (81%). Th...
James R. Mickelson - One of the best experts on this subject based on the ideXlab platform.
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genome wide signatures of selection reveal genes associated with performance in american Quarter Horse subpopulations
Frontiers in Genetics, 2018Co-Authors: Felipe Avila, James R. Mickelson, Robert J Schaefer, Molly E MccueAbstract:Selective breeding for athletic performance in various disciplines has resulted in population stratification within the American Quarter Horse (QH) breed. The goals of this study were to utilize high density genotype data to: (1) identify genomic regions undergoing positive selection within and among QH subpopulations; (2) investigate haplotype structure within each QH subpopulation; and (3) identify candidate genes within genomic regions of interest (ROI), as well as biological pathways, predicted to play a role in elite performance in each group. For that, 65K SNP genotyping data on 143 elite individuals from 6 QH subpopulations (cutting, halter, racing, reining, western pleasure, and working cow) were imputed to 2M SNPs. Signatures of selection were identified using FST-based (di ) and haplotype-based (hapFLK) analyses, accompanied by identification of local haplotype structure and sharing within subpopulations (hapQTL). Regions undergoing positive selection were identified on all 31 autosomes, and ROI on 2 chromosomes were identified by all 3 methods combined. Genes within each ROI were retrieved and used to identify pathways and genes that might contribute to performance in each subpopulation. These included, among others, candidate genes associated with skeletal muscle development, metabolism, and central nervous system development. This work improves our understanding of equine breed development, and provides breeders with a better understanding of how selective breeding impacts the performance of QH populations.
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Table_4_Genome-Wide Signatures of Selection Reveal Genes Associated With Performance in American Quarter Horse Subpopulations.XLSX
2018Co-Authors: Felipe Avila, James R. Mickelson, Robert J Schaefer, Molly E MccueAbstract:Selective breeding for athletic performance in various disciplines has resulted in population stratification within the American Quarter Horse (QH) breed. The goals of this study were to utilize high density genotype data to: (1) identify genomic regions undergoing positive selection within and among QH subpopulations; (2) investigate haplotype structure within each QH subpopulation; and (3) identify candidate genes within genomic regions of interest (ROI), as well as biological pathways, predicted to play a role in elite performance in each group. For that, 65K SNP genotyping data on 143 elite individuals from 6 QH subpopulations (cutting, halter, racing, reining, western pleasure, and working cow) were imputed to 2M SNPs. Signatures of selection were identified using FST-based (di) and haplotype-based (hapFLK) analyses, accompanied by identification of local haplotype structure and sharing within subpopulations (hapQTL). Regions undergoing positive selection were identified on all 31 autosomes, and ROI on 2 chromosomes were identified by all 3 methods combined. Genes within each ROI were retrieved and used to identify pathways and genes that might contribute to performance in each subpopulation. These included, among others, candidate genes associated with skeletal muscle development, metabolism, and central nervous system development. This work improves our understanding of equine breed development, and provides breeders with a better understanding of how selective breeding impacts the performance of QH populations.
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Table_15_Genome-Wide Signatures of Selection Reveal Genes Associated With Performance in American Quarter Horse Subpopulations.XLSX
2018Co-Authors: Felipe Avila, James R. Mickelson, Robert J Schaefer, Molly E MccueAbstract:Selective breeding for athletic performance in various disciplines has resulted in population stratification within the American Quarter Horse (QH) breed. The goals of this study were to utilize high density genotype data to: (1) identify genomic regions undergoing positive selection within and among QH subpopulations; (2) investigate haplotype structure within each QH subpopulation; and (3) identify candidate genes within genomic regions of interest (ROI), as well as biological pathways, predicted to play a role in elite performance in each group. For that, 65K SNP genotyping data on 143 elite individuals from 6 QH subpopulations (cutting, halter, racing, reining, western pleasure, and working cow) were imputed to 2M SNPs. Signatures of selection were identified using FST-based (di) and haplotype-based (hapFLK) analyses, accompanied by identification of local haplotype structure and sharing within subpopulations (hapQTL). Regions undergoing positive selection were identified on all 31 autosomes, and ROI on 2 chromosomes were identified by all 3 methods combined. Genes within each ROI were retrieved and used to identify pathways and genes that might contribute to performance in each subpopulation. These included, among others, candidate genes associated with skeletal muscle development, metabolism, and central nervous system development. This work improves our understanding of equine breed development, and provides breeders with a better understanding of how selective breeding impacts the performance of QH populations.
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Table_12_Genome-Wide Signatures of Selection Reveal Genes Associated With Performance in American Quarter Horse Subpopulations.XLSX
2018Co-Authors: Felipe Avila, James R. Mickelson, Robert J Schaefer, Molly E MccueAbstract:Selective breeding for athletic performance in various disciplines has resulted in population stratification within the American Quarter Horse (QH) breed. The goals of this study were to utilize high density genotype data to: (1) identify genomic regions undergoing positive selection within and among QH subpopulations; (2) investigate haplotype structure within each QH subpopulation; and (3) identify candidate genes within genomic regions of interest (ROI), as well as biological pathways, predicted to play a role in elite performance in each group. For that, 65K SNP genotyping data on 143 elite individuals from 6 QH subpopulations (cutting, halter, racing, reining, western pleasure, and working cow) were imputed to 2M SNPs. Signatures of selection were identified using FST-based (di) and haplotype-based (hapFLK) analyses, accompanied by identification of local haplotype structure and sharing within subpopulations (hapQTL). Regions undergoing positive selection were identified on all 31 autosomes, and ROI on 2 chromosomes were identified by all 3 methods combined. Genes within each ROI were retrieved and used to identify pathways and genes that might contribute to performance in each subpopulation. These included, among others, candidate genes associated with skeletal muscle development, metabolism, and central nervous system development. This work improves our understanding of equine breed development, and provides breeders with a better understanding of how selective breeding impacts the performance of QH populations.
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Image_6_Genome-Wide Signatures of Selection Reveal Genes Associated With Performance in American Quarter Horse Subpopulations.TIF
2018Co-Authors: Felipe Avila, James R. Mickelson, Robert J Schaefer, Molly E MccueAbstract:Selective breeding for athletic performance in various disciplines has resulted in population stratification within the American Quarter Horse (QH) breed. The goals of this study were to utilize high density genotype data to: (1) identify genomic regions undergoing positive selection within and among QH subpopulations; (2) investigate haplotype structure within each QH subpopulation; and (3) identify candidate genes within genomic regions of interest (ROI), as well as biological pathways, predicted to play a role in elite performance in each group. For that, 65K SNP genotyping data on 143 elite individuals from 6 QH subpopulations (cutting, halter, racing, reining, western pleasure, and working cow) were imputed to 2M SNPs. Signatures of selection were identified using FST-based (di) and haplotype-based (hapFLK) analyses, accompanied by identification of local haplotype structure and sharing within subpopulations (hapQTL). Regions undergoing positive selection were identified on all 31 autosomes, and ROI on 2 chromosomes were identified by all 3 methods combined. Genes within each ROI were retrieved and used to identify pathways and genes that might contribute to performance in each subpopulation. These included, among others, candidate genes associated with skeletal muscle development, metabolism, and central nervous system development. This work improves our understanding of equine breed development, and provides breeders with a better understanding of how selective breeding impacts the performance of QH populations.
S A Vallance - One of the best experts on this subject based on the ideXlab platform.
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case control study of high speed exercise history of thoroughbred and Quarter Horse raceHorses that died related to a complete scapular fracture
Equine Veterinary Journal, 2013Co-Authors: S A Vallance, Peta L Hitchens, Rachel Entwistle, Ian A Gardner, Susan M. StoverAbstract:Summary Reasons for performing study: Identification of exercise history patterns that are related to catastrophic scapular fracture will facilitate prevention of raceHorse fatalities. Objectives: To determine if exercise patterns are associated with scapular fracture in Thoroughbred (TB) and Quarter Horse (QH) raceHorses. Methods: High-speed exercise histories for 65 TB and 26 QH raceHorses that had a complete scapular fracture (cases) and 2 matched control raceHorses were retrospectively studied. Exercise variables were created from lifetime race and official timed workout reports. Associations between exercise variables and scapular fracture were investigated using conditional logistic regression. Results: Thoroughbreds with a scapular fracture had a greater number of workouts, events (combined works and races), and mean event distances than QHs with a scapular fracture. Quarter Horses worked less frequently and accumulated distance at a lower rate than TBs. Breed differences were not found for career race number or length, time between races or lay-up variables for Horses with ≥1 lay-up. For both breeds, cases had fewer events, lower recent accumulated distance and fewer active days in training than controls; however, a subset of TB cases with >10 events since lay-up had a longer active career than controls. For QHs that had a lay-up, total and mean lay-up times were greater for cases than controls. Multivariable models revealed that odds ratios (OR) of scapular fracture were greater for TBs that had not yet raced (OR = 23.19; 95% confidence interval (CI) 3.03–177.38) and lower for QHs with more events (OR = 0.71; 95% CI 0.54–0.94). Conclusions and clinical relevance: RaceHorses that are in early high-speed training but behind that of their training cohort should be examined for signs of scapular stress remodelling. Quarter Horses that had a prolonged lay-up and TBs that have endured high-speed training for a longer duration than that of their training cohort also were at greater risk.
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characteristics of thoroughbred and Quarter Horse raceHorses that sustained a complete scapular fracture
Equine Veterinary Journal, 2012Co-Authors: S A Vallance, Hailu Kinde, Susan M. Stover, Rick Arthur, Janet Moore, James T Case, Rachel Entwistle, Bradd C Barr, Mark L AndersonAbstract:Summary Reasons for performing study: To determine if scapular fractures occur in raceHorses with distinctive characteristics. Objectives: To test the hypothesis that Thoroughbred (TB) and Quarter Horse (QH) raceHorses with a scapular fracture have similar characteristics that are different from those of their respective racetrack populations. Methods: Necropsy findings, case details, last race information and career earnings for TB and QH raceHorses that had a scapular fracture in California between 1990 and 2008 were retrospectively compared between breeds. Horse signalment, career earnings, career starts and race characteristics were obtained for all California raceHorses. Comparisons were made between affected Horses, other raceHorses that died, and all Horses that raced, in California during the 19 year period. Results: Seventy-three TB and 28 QH raceHorses had a similar, complete comminuted scapular fracture with an articular component, and right forelimb predilection. The QHs had a higher incidence of scapular fracture incurred during racing than TBs (0.98 vs. 0.39/1000 starters). The TB and QH incident rates for musculoskeletal deaths incurred racing were 20.5 and 17.5/1000 starters, respectively; however, a greater proportion of TB musculoskeletal deaths occurred training (40% vs. 8%). Horses with a scapular fracture were more likely to be male and aged 2 or ≥5 years than the racetrack population. Most affected QHs (64%) were 2-year-olds; most TBs (74%) were aged ≥3 years. Scapular fractures occurred more commonly during racing in QHs (70%) than TBs (44%). Race-related scapular fracture was more likely to occur in a Maiden race than in a non-Maiden race. Horses with a scapular fracture had fewer career starts than the racetrack population. Conclusions and potential relevance: Despite breed differences for signalment and exercise distances, both breeds incur a complete scapular fracture that is more likely to occur in the right scapula of young and older, male raceHorses, early in their race career or after few races. Quarter Horses sustain a catastrophic scapular fracture more frequently than TBs.
Molly E Mccue - One of the best experts on this subject based on the ideXlab platform.
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genome wide signatures of selection reveal genes associated with performance in american Quarter Horse subpopulations
Frontiers in Genetics, 2018Co-Authors: Felipe Avila, James R. Mickelson, Robert J Schaefer, Molly E MccueAbstract:Selective breeding for athletic performance in various disciplines has resulted in population stratification within the American Quarter Horse (QH) breed. The goals of this study were to utilize high density genotype data to: (1) identify genomic regions undergoing positive selection within and among QH subpopulations; (2) investigate haplotype structure within each QH subpopulation; and (3) identify candidate genes within genomic regions of interest (ROI), as well as biological pathways, predicted to play a role in elite performance in each group. For that, 65K SNP genotyping data on 143 elite individuals from 6 QH subpopulations (cutting, halter, racing, reining, western pleasure, and working cow) were imputed to 2M SNPs. Signatures of selection were identified using FST-based (di ) and haplotype-based (hapFLK) analyses, accompanied by identification of local haplotype structure and sharing within subpopulations (hapQTL). Regions undergoing positive selection were identified on all 31 autosomes, and ROI on 2 chromosomes were identified by all 3 methods combined. Genes within each ROI were retrieved and used to identify pathways and genes that might contribute to performance in each subpopulation. These included, among others, candidate genes associated with skeletal muscle development, metabolism, and central nervous system development. This work improves our understanding of equine breed development, and provides breeders with a better understanding of how selective breeding impacts the performance of QH populations.
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Table_4_Genome-Wide Signatures of Selection Reveal Genes Associated With Performance in American Quarter Horse Subpopulations.XLSX
2018Co-Authors: Felipe Avila, James R. Mickelson, Robert J Schaefer, Molly E MccueAbstract:Selective breeding for athletic performance in various disciplines has resulted in population stratification within the American Quarter Horse (QH) breed. The goals of this study were to utilize high density genotype data to: (1) identify genomic regions undergoing positive selection within and among QH subpopulations; (2) investigate haplotype structure within each QH subpopulation; and (3) identify candidate genes within genomic regions of interest (ROI), as well as biological pathways, predicted to play a role in elite performance in each group. For that, 65K SNP genotyping data on 143 elite individuals from 6 QH subpopulations (cutting, halter, racing, reining, western pleasure, and working cow) were imputed to 2M SNPs. Signatures of selection were identified using FST-based (di) and haplotype-based (hapFLK) analyses, accompanied by identification of local haplotype structure and sharing within subpopulations (hapQTL). Regions undergoing positive selection were identified on all 31 autosomes, and ROI on 2 chromosomes were identified by all 3 methods combined. Genes within each ROI were retrieved and used to identify pathways and genes that might contribute to performance in each subpopulation. These included, among others, candidate genes associated with skeletal muscle development, metabolism, and central nervous system development. This work improves our understanding of equine breed development, and provides breeders with a better understanding of how selective breeding impacts the performance of QH populations.
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Table_15_Genome-Wide Signatures of Selection Reveal Genes Associated With Performance in American Quarter Horse Subpopulations.XLSX
2018Co-Authors: Felipe Avila, James R. Mickelson, Robert J Schaefer, Molly E MccueAbstract:Selective breeding for athletic performance in various disciplines has resulted in population stratification within the American Quarter Horse (QH) breed. The goals of this study were to utilize high density genotype data to: (1) identify genomic regions undergoing positive selection within and among QH subpopulations; (2) investigate haplotype structure within each QH subpopulation; and (3) identify candidate genes within genomic regions of interest (ROI), as well as biological pathways, predicted to play a role in elite performance in each group. For that, 65K SNP genotyping data on 143 elite individuals from 6 QH subpopulations (cutting, halter, racing, reining, western pleasure, and working cow) were imputed to 2M SNPs. Signatures of selection were identified using FST-based (di) and haplotype-based (hapFLK) analyses, accompanied by identification of local haplotype structure and sharing within subpopulations (hapQTL). Regions undergoing positive selection were identified on all 31 autosomes, and ROI on 2 chromosomes were identified by all 3 methods combined. Genes within each ROI were retrieved and used to identify pathways and genes that might contribute to performance in each subpopulation. These included, among others, candidate genes associated with skeletal muscle development, metabolism, and central nervous system development. This work improves our understanding of equine breed development, and provides breeders with a better understanding of how selective breeding impacts the performance of QH populations.
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Table_12_Genome-Wide Signatures of Selection Reveal Genes Associated With Performance in American Quarter Horse Subpopulations.XLSX
2018Co-Authors: Felipe Avila, James R. Mickelson, Robert J Schaefer, Molly E MccueAbstract:Selective breeding for athletic performance in various disciplines has resulted in population stratification within the American Quarter Horse (QH) breed. The goals of this study were to utilize high density genotype data to: (1) identify genomic regions undergoing positive selection within and among QH subpopulations; (2) investigate haplotype structure within each QH subpopulation; and (3) identify candidate genes within genomic regions of interest (ROI), as well as biological pathways, predicted to play a role in elite performance in each group. For that, 65K SNP genotyping data on 143 elite individuals from 6 QH subpopulations (cutting, halter, racing, reining, western pleasure, and working cow) were imputed to 2M SNPs. Signatures of selection were identified using FST-based (di) and haplotype-based (hapFLK) analyses, accompanied by identification of local haplotype structure and sharing within subpopulations (hapQTL). Regions undergoing positive selection were identified on all 31 autosomes, and ROI on 2 chromosomes were identified by all 3 methods combined. Genes within each ROI were retrieved and used to identify pathways and genes that might contribute to performance in each subpopulation. These included, among others, candidate genes associated with skeletal muscle development, metabolism, and central nervous system development. This work improves our understanding of equine breed development, and provides breeders with a better understanding of how selective breeding impacts the performance of QH populations.
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Image_6_Genome-Wide Signatures of Selection Reveal Genes Associated With Performance in American Quarter Horse Subpopulations.TIF
2018Co-Authors: Felipe Avila, James R. Mickelson, Robert J Schaefer, Molly E MccueAbstract:Selective breeding for athletic performance in various disciplines has resulted in population stratification within the American Quarter Horse (QH) breed. The goals of this study were to utilize high density genotype data to: (1) identify genomic regions undergoing positive selection within and among QH subpopulations; (2) investigate haplotype structure within each QH subpopulation; and (3) identify candidate genes within genomic regions of interest (ROI), as well as biological pathways, predicted to play a role in elite performance in each group. For that, 65K SNP genotyping data on 143 elite individuals from 6 QH subpopulations (cutting, halter, racing, reining, western pleasure, and working cow) were imputed to 2M SNPs. Signatures of selection were identified using FST-based (di) and haplotype-based (hapFLK) analyses, accompanied by identification of local haplotype structure and sharing within subpopulations (hapQTL). Regions undergoing positive selection were identified on all 31 autosomes, and ROI on 2 chromosomes were identified by all 3 methods combined. Genes within each ROI were retrieved and used to identify pathways and genes that might contribute to performance in each subpopulation. These included, among others, candidate genes associated with skeletal muscle development, metabolism, and central nervous system development. This work improves our understanding of equine breed development, and provides breeders with a better understanding of how selective breeding impacts the performance of QH populations.
Rachel Entwistle - One of the best experts on this subject based on the ideXlab platform.
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case control study of high speed exercise history of thoroughbred and Quarter Horse raceHorses that died related to a complete scapular fracture
Equine Veterinary Journal, 2013Co-Authors: S A Vallance, Peta L Hitchens, Rachel Entwistle, Ian A Gardner, Susan M. StoverAbstract:Summary Reasons for performing study: Identification of exercise history patterns that are related to catastrophic scapular fracture will facilitate prevention of raceHorse fatalities. Objectives: To determine if exercise patterns are associated with scapular fracture in Thoroughbred (TB) and Quarter Horse (QH) raceHorses. Methods: High-speed exercise histories for 65 TB and 26 QH raceHorses that had a complete scapular fracture (cases) and 2 matched control raceHorses were retrospectively studied. Exercise variables were created from lifetime race and official timed workout reports. Associations between exercise variables and scapular fracture were investigated using conditional logistic regression. Results: Thoroughbreds with a scapular fracture had a greater number of workouts, events (combined works and races), and mean event distances than QHs with a scapular fracture. Quarter Horses worked less frequently and accumulated distance at a lower rate than TBs. Breed differences were not found for career race number or length, time between races or lay-up variables for Horses with ≥1 lay-up. For both breeds, cases had fewer events, lower recent accumulated distance and fewer active days in training than controls; however, a subset of TB cases with >10 events since lay-up had a longer active career than controls. For QHs that had a lay-up, total and mean lay-up times were greater for cases than controls. Multivariable models revealed that odds ratios (OR) of scapular fracture were greater for TBs that had not yet raced (OR = 23.19; 95% confidence interval (CI) 3.03–177.38) and lower for QHs with more events (OR = 0.71; 95% CI 0.54–0.94). Conclusions and clinical relevance: RaceHorses that are in early high-speed training but behind that of their training cohort should be examined for signs of scapular stress remodelling. Quarter Horses that had a prolonged lay-up and TBs that have endured high-speed training for a longer duration than that of their training cohort also were at greater risk.
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characteristics of thoroughbred and Quarter Horse raceHorses that sustained a complete scapular fracture
Equine Veterinary Journal, 2012Co-Authors: S A Vallance, Hailu Kinde, Susan M. Stover, Rick Arthur, Janet Moore, James T Case, Rachel Entwistle, Bradd C Barr, Mark L AndersonAbstract:Summary Reasons for performing study: To determine if scapular fractures occur in raceHorses with distinctive characteristics. Objectives: To test the hypothesis that Thoroughbred (TB) and Quarter Horse (QH) raceHorses with a scapular fracture have similar characteristics that are different from those of their respective racetrack populations. Methods: Necropsy findings, case details, last race information and career earnings for TB and QH raceHorses that had a scapular fracture in California between 1990 and 2008 were retrospectively compared between breeds. Horse signalment, career earnings, career starts and race characteristics were obtained for all California raceHorses. Comparisons were made between affected Horses, other raceHorses that died, and all Horses that raced, in California during the 19 year period. Results: Seventy-three TB and 28 QH raceHorses had a similar, complete comminuted scapular fracture with an articular component, and right forelimb predilection. The QHs had a higher incidence of scapular fracture incurred during racing than TBs (0.98 vs. 0.39/1000 starters). The TB and QH incident rates for musculoskeletal deaths incurred racing were 20.5 and 17.5/1000 starters, respectively; however, a greater proportion of TB musculoskeletal deaths occurred training (40% vs. 8%). Horses with a scapular fracture were more likely to be male and aged 2 or ≥5 years than the racetrack population. Most affected QHs (64%) were 2-year-olds; most TBs (74%) were aged ≥3 years. Scapular fractures occurred more commonly during racing in QHs (70%) than TBs (44%). Race-related scapular fracture was more likely to occur in a Maiden race than in a non-Maiden race. Horses with a scapular fracture had fewer career starts than the racetrack population. Conclusions and potential relevance: Despite breed differences for signalment and exercise distances, both breeds incur a complete scapular fracture that is more likely to occur in the right scapula of young and older, male raceHorses, early in their race career or after few races. Quarter Horses sustain a catastrophic scapular fracture more frequently than TBs.
