Italian researchers who identified a significant biochemical response in eventing horses after the cross-country phase suggest more work is needed to assess recovery times and define possible effects on their immune function.
Dr Emanuela Valle and her colleagues from a range of Italian universities set out to measure selected blood proteins and lymphocyte levels – both oxidative stress markers.
They carried out their study on eight warmblood eventers who took part in a national two-day event.
The researchers set to measure markers of what is known as the acute phase response (APR) – a complex systemic early-defence mechanism activated by the body to deal with the likes of trauma, infection, stress, inflammation, and tumours. It plays an important role in the body’s immune response.
The researchers collected blood samples from the horses, who ranged in age from seven to 13, at rest and then 10 minutes after their completion of the cross-country test on the second day.
They then analysed key blood proteins to gauge changes in levels brought about by the cross-country run. The laboratory work included a complete blood count and an assessment of subpopulations of lymphocytes (a form of white blood cells) in the collected samples.
Exercise caused a significant increase in red blood cell numbers, haemoglobin, packed cell volume, neutrophils, white blood cells, and lymphocyte numbers, they reported. However, these values remained within the normal range.
Two lymphocyte subpopulations – the CD4+ and CD8+ cells – increased significantly, whereas the CD21+ lymphocytes decreased.
The researchers found significant increases in serum amyloid A, lysozyme and protein carbonyl derivates – all markers of the acute phase response – following the cross-country run.
The results supported the hypothesis that two-day eventing may significantly alter acute phase response markers in horses, they reported in the Journal of Animal Physiology and Animal Nutrition.
The research team acknowledged the relatively small sample size and said sampling times had to fit in around the official running of the event.
“Therefore, further studies were needed to investigate the time required for recovery to base values in order to define the possible effects on the immune function of competition horses,” they wrote.
Valle, E., Zanatta, R., Odetti, P., Traverso, N., Furfaro, A., Bergero, D., Badino, P., Girardi, C., Miniscalco, B., Bergagna, S., Tarantola, M., Intorre, L. and Odore, R. (2015), Effects of competition on acute phase proteins and lymphocyte subpopulations – oxidative stress markers in eventing horses. Journal of Animal Physiology and Animal Nutrition, 99: 856–863. doi: 10.1111/jpn.12289
The abstract can be read here.