Impacts of Exercise and DHA/EPA/GLA Supplementation on Plasma Cytokines in Thoroughbreds

Timely resolution of inflammation is essential to maintain performance horse health. Thirteen Thoroughbred horses (11 geldings, 2 fillies; mean ± SD 3.7±1.6 yr, 488±38 kg) enrolled in an early race training program were used to test two hypotheses: (1) anti-inflammatory interleukin (IL)-4 and IL-10 concentrations would decrease and pro-inflammatory IL-8 and tumour necrosis factor (TNF)-alpha concentrations would increase following a standardized exercise test (SET) on a racetrack; and (2) supplementation of a 4.3 g/d eicosapentaenoic acid, 3.5 g/d docosahexaenoic acid, and 5.3 g/d gamma-linoleic acid blend (GLA; n=7) would mitigate the pro-inflammatory response compared to 9.9 g/d alpha-linolenic acid and 8.8 g/d linoleic acid (CON; n=6). Following 12 wk of supplementation, plasma was collected pre-, and 4, 24, and 48 h post-SET. Cytokine concentrations were determined using custom Meso Scale Discovery U-Plex kits. Data were analyzed using PROC MIXED with repeated measures (time) in SAS v9.4 with time, diet, and time × diet as fixed effects. Plasma IL-10 was greater 4 h post- (P≤0.001) and tended to be greater 24 h post-SET (P≤0.1) than pre- or 48 h post-SET. Overall, IL-10 tended to be greater in GLA than CON horses (P=0.07). GLA horses had lower IL-8 concentrations at 24 h post-SET than all other time points (P≤0.04) resulting in greater IL-8 concentrations in CON than GLA horses (P=0.02) at 24 h post-SET. There was no effect of exercise or diet on plasma IL-4 or TNF-αlpha concentrations. These results suggest EPA/DHA/GLA supplementation may promote a less inflammatory environment in plasma following an exercise stressor in Thoroughbreds horses.

Wesolowski, L.T., J.L. Simons, J.D. Pagan, and S.H. White-Springer. 2022. Impacts of exercise and DHA/EPA/GLA supplementation on plasma cytokines in Thoroughbreds. In: Proceedings of the International Conference on Equine Exercise Physiology (ICEEP) 11. Comparative Exercise Physiology 22 (Supp 1):S30.