Author ORCID Identifier

https://orcid.org/0009-0004-5402-3002

Date Available

8-3-2025

Year of Publication

2025

Document Type

Master's Thesis

Degree Name

Master of Science (MS)

College

Agriculture, Food and Environment

Department/School/Program

Veterinary Science

Faculty

Allen Page

Faculty

Emma Adam

Abstract

Evidence that fractures in Thoroughbred racehorses are outcomes of chronic bone microdamage has led to extensive research into identifying horses at increased risk of fracture. This includes the use of biomarkers and messenger RNA (mRNA) as a measure of bone turnover. Previous research has found expression differences in horses with fractures compared to controls. Utilizing pre-race whole blood samples collected over an 18-month period from Thoroughbred racehorses in Southern California, RNA-sequencing was conducted on horses with bone fractures and race-matched controls to identify differences in gene expression. Focusing on third metacarpal (MC3) and proximal sesamoid bone (PSB) fractures, differentially expressed genes were identified. Ingenuity Pathway Analysis was used to identify activated and inactivated pathways and upstream regulators, and Weighted Gene Co-Expression Network Analysis was conducted. Genes identified in multiple analyses were assessed for log2 fold change to create a list of 23 genes of interest. Differences in expression patterns between MC3 and PSB fractures were identified. MC3 fractures showed expression suggestive of an inhibition of remodeling, and PSB fractures showed expression suggestive of enhanced osteogenesis. Additionally, many of the top genes were related to neural function, suggesting a potential link between skeletal interoception and racehorse fractures.

Digital Object Identifier (DOI)

https://doi.org/10.13023/etd.2025.308

Funding Information

This study was support by the Kentucky Horse Racing Commission (Kentucky Horse Racing and Gaming Corporation), Kentucky Thoroughbred Association, Stronach Group, New York Racing Association, Kentucky Thoroughbred Owners and Breeders, Inc., Thoroughbred Owners of California, Thoroughbred Owners and Breeders Association, Keeneland Association, Inc., Del Mar Thoroughbred Club, and Breeders' Cup between 2022 and 2025.

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