Effects of competition on acute phase proteins and lymphocyte subpopulations - oxidative stress markers in eventing horses.
Authors: Valle E, Zanatta R, Odetti P, Traverso N, Furfaro A, Bergero D, Badino P, Girardi C, Miniscalco B, Bergagna S, Tarantola M, Intorre L, Odore R
Journal: Journal of animal physiology and animal nutrition
Summary
# Editorial Summary: Competition-Induced Stress Markers in Event Horses Two-day eventing competitions trigger measurable acute phase and oxidative stress responses in horses, according to research examining eight Warmblood competitors during an official national event. Researchers collected blood samples at rest and within 10 minutes of completing the cross-country phase, measuring acute phase proteins (haptoglobin and serum amyloid A), oxidative stress markers including advanced glycation end products and their protein adducts (pentosidine, malondialdehyde and hydroxynonenal), lysozyme activity, and immune cell populations (CD4+, CD8+, and CD21+ lymphocytes). Whilst red blood cell parameters, haemoglobin and white blood cell counts remained within normal ranges, significant elevations occurred in serum amyloid A, lysozyme, and protein carbonyl derivates post-competition, alongside a notable shift in lymphocyte subpopulations—increased CD4+ and CD8+ cells but decreased CD21+ B cells. These findings confirm that two-day eventing substantially alters immune function and oxidative stress markers, suggesting competition imposes considerable physiological demand beyond simple cardiovascular exertion. For practitioners managing event horses, this reinforces the importance of targeted recovery protocols, antioxidant support, and immune monitoring during the competition season, though the authors acknowledge their small sample size and call for longitudinal studies tracking recovery timelines to determine whether repeat competition compromises long-term immune competence.
Read the full abstract on PubMed
Practical Takeaways
- •Competition-related stress induces measurable acute phase and oxidative stress responses in eventing horses; monitoring these markers may help assess recovery demands and welfare after intense events
- •Changes in lymphocyte subpopulations suggest competition temporarily alters immune cell distribution; allow adequate recovery time between events to restore baseline immune status
- •While haematological changes occurred, values remained normal; however, biochemical markers of oxidative stress may be more sensitive indicators of competition impact than standard blood parameters
Key Findings
- •Two-day eventing competition significantly increased serum amyloid A (SAA), lysozyme, and protein carbonyl derivatives (HNE, AGEs, PENT) compared to resting values
- •CD4+ and CD8+ lymphocyte populations significantly increased post-competition while CD21+ lymphocytes decreased
- •Red blood cell number, haemoglobin, packed cell volume, neutrophils, white blood cells and total lymphocytes all increased but remained within normal ranges
- •Study identified need for further research on recovery timelines and effects on immune function in competition horses due to small sample size and single sampling timepoint limitations