Haematological Response Associated with Repeted Show Jumping Competition in Horse

Background: Several studies have demonstrated the beneficial effect of exercise; even in human that in horse, but exercise could also represent a physical stress that challenging body homeostasis. Exercise stress pushes the body to find a dynamic equilibrium through adaptive changes to ensure proper management of stress caused by maximal exercise. These changes affect various composition of body fluids, in particular changes in blood composition including an increase in Red Blood Cells (RBC), Hematocrit (Hct) and Hemoglobin (Hgb) values and a change in Platelets (Plt) count. The objective of the present study was to evaluate the effectof repeated jumping exercise on haematological parameters in horse. Material, Methods & Results:For this purpose we evaluated the modifications occurring in cell blood count (CBC) in horses during two international three stars *** show jumping competition performed in two consecutive weekend. After routine clinical examination, twelve well trained Italian Saddle horses were enrolled for this study. For every subject, Red blood cell (RBC), haematocrit (HCT), haemoglobin (HGB) and platelets (PLT) were assessed. Blood samples were collected: in the morning after the meal (7:30-8:00 AM), before the beginning of the competition (R1) and within 10 min after competition ending (C1S1, C1S2) and on the day after competition (R2). The same procedure was followed on the second weekend (C2S1, C2S2, R3). Whole blood samples were placed on ice pending analysis that were performed within 2 h after collection and immediately taken to the laboratory for analysis. The obtained data were analyzed with Stats package of R: R Core Team (2013). One-way repeated measures analysis of variance (ANOVA) showed a significant effect on sampling time (P < 0.05) concerning every studied parameter. In particular a significant increase of RBC in C1S1, C1S2, C2S1 and C2S2 versus R1, R2 and R3. Same results were found for Hgb and Hct that have showed a significant increase in C1S1, C1S2, C2S1 and C2S2 versus R1, R2 and R3. A significant increment in Plt was found in R3 and R2 versus R1 and in R3 versus C1S1 and C1S2. Discussion:In this study it was possible to observe an increasing of RBC, Hgb and Hct levels immediately after the exercise and returning to basal levels during resting time. Instead Plt values increase during resting time and the proximity of the competition induce a thrombocytosis during the second weekend. These increases may be related to the mechanisms of physiological adaptation required in course of exercise, increased oxygen demand by the muscles, release of circulating catecholamine resulting in spleen contraction, and to negative effect of the exercise like fluid loss resulting in dehydration. The return to normal levels during the resting time and the similar trend during the second weekend denotes as a horse, that has been well trained, is able to counterbalance the stress of two sessions of competition so close together. The trend of Plt denotes an increase during the resting time. This demonstrates the slowness in the reuptake of these, so during haematological evaluation in athlete particular attention must be put to Plt evaluation, because exercise stress induces not only the increase of their number, but also the increase of their reactivity and of their capacity to form aggregates, that can be implicated in thrombosis and some other cardiovascular diseases.