Haematological Changes Following Reining Trials in Quarter Horses

Background: It is well known that exercise induce physiological stress on horse’s body system, causing signifi cant changes in blood components. Haematological changes associated with exercise have been widely analyzed to provide information about health status and athletic performance in horses. Numerous studies have been performed to investigate the response of haematological parameters to various types of exercise. However, only few studies dealt with reining horses. Reining is a typical Western discipline characterised by manoeuvres requiring fast and powerful muscle contractions and motor skills. The aim of this study was to assess the effect of a reining training session on some haematological parameters. Material, Methods & Results: In the present study, eight Quarter Horses aged 5-15 years (three stallions and fi ve mares; mean body weight 480 ± 60 kg) were used to establish physiologic responses to a reining training session. All subjects were housed at the same horse training centre in Sicily, Italy. All horses were subjected to the reining pattern 5 of National Reining Horse Association (NRHA), consisting of 2 large circle gallop (G1; G2), 1 small circle lope (L1), 1 stop (STOP), 4 spins (S1), 2 large circle gallop (G3; G4), 1 small circle lope (L2), 1 stop (STOP), 4 spins (S2), 1 large circle gallop (G5), lead change (LC1), 1 small circle lope (L3), 1 large circle gallop (G6), lead change (LC2), 1 large circle gallop (G7), lead change (LC3), 2 rollbacks (RB1, RB2), 1 stop (STOP) and backing (B). Blood samples were collected from each animal before (T0) and immediately after completion of the pattern (T1). Further samples were collected after 1 h (T2), 2 h (T3) and 24 h (T4) after exercise, during the recovery period. Blood was analysed for haematological parameters using an automatic analyser. One way repeated measure analysis of variance (ANOVA) showed a statistical signifi cant effect of time on the following parameters: red blood cell (P < 0.0001), haemoglobin concentration (P < 0.0001), haematocrit (P < 0.0001) and white blood cell (P < 0.05). The application of Bonferroni’s post-hoc comparison showed a statistical signifi cant increase in red blood cell, haemoglobin and haematocrit values at T1 compared to T0, T2, T3 and T4. White blood cell count increased at T1 and T4 compared to T0. Discussion: Exercise has variable effects on hematological parameters. These differences might depend on both intensity and duration of physical effort. The increase in erythrocyte numbers together with the increase in Hb concentrations after exercise is probably a sequela of splenic contraction and subsequent release of erythrocytes with altered erythrocytic indices. High red blood cell counts and haemoglobin concentrations allow to increase oxygen transportation capacity to body tissues. In association with the increase in red blood cell and haemoglobin concentrations an increase in haematocrit. This might be due to exercise-induced fl uid shifts as well as to splenic contraction. The spleen releases not only the stored erythrocytes but also the leukocytes into the peripheral circulation. These changes are likely secondary to catecholamine release and splenic contraction. The results of this study showed that a reining training session induces an increase in red blood cell, haemoglobin concentration, haematocrit and white blood cell concentrations, immediately after completion of the pattern, returning to basal values 1 h after exercise.