Date of Award

8-2026

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Animal and Veterinary Sciences

Committee Chair/Advisor

Dr. Kristine Vernon

Committee Member

Dr. Ahmed Ali

Committee Member

Dr. William Bridges

Committee Member

Dr. Jessica Leatherwood

Abstract

Osteoarthritis (OA) is considered a leading cause of lost use and premature retirement in the equine industry, with substantial financial and welfare consequences. Conjugated linoleic acid (CLA) has demonstrated anti-inflammatory effects in horses at maintenance without confirmed OA; however, previous research has recommended evaluating its effects in exercised horses with pre-existing OA. The objective of the current study was to investigate the effects of dietary CLA supplementation on exercised horses with confirmed OA. It was hypothesized that CLA supplementation would reduce intra-articular inflammation, which would be reflected by improvements in functional outcomes, including stride length, joint flexion, and ridden behavior. Fifteen equestrian team horses with radiographically confirmed joint disease of the tarsus, metacarpophalangeal joint, and/or carpus were blocked by breed, age, sex, and management system and randomly assigned to receive CLA (n = 8) or soybean oil (SO; n = 7) at 0.02% BW for 16 weeks, followed by a 5-week washout period. Horses remained in regular work, completing 3-5 weekly 1-hour lessons at the walk, trot/jog, and canter/lope. Plasma fatty acids were analyzed at weeks 0, 16, and 23; synovial fluid was collected at weeks 0, 8, and 16 for prostaglandin E2 (PGE2) quantification. Gait kinematics and ridden behavior were video recorded every 4 weeks. Plasma CLA was detectable at week 16 in CLA-supplemented horses and cleared by week 23, while CLA remained undetectable in SO horses throughout the study. Synovial PGE2 concentrations were significantly lower in CLA horses at week 16 and trended downward over time, whereas SO horses' PGE2 concentrations trended upward. CLA horses had significantly longer stride length and greater elbow joint flexion at the walk and trot compared with SO horses. There was no significant treatment effect on overall RHpE scores; however, select individual pain behaviors differed significantly between treatment groups. The temporal alignment across all three outcome domains forms a coherent, internally consistent biological argument for CLA as an effective anti-inflammatory supplement. Taken together, these findings support CLA as a practical, evidence-based, non-pharmacological management option for performance horses with OA and establish a foundation for future research with larger sample sizes and more controlled conditions.

Author ORCID Identifier

https://orcid.org/0009-0000-3761-8160

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Available for download on Tuesday, August 31, 2027

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