Dynamic adaptation of hematological parameters, albumin, and non-esterified fatty acids in saddlebred and standardbred horses during exercise

The response to exercise following a rest period may vary among horse breeds based on the importance of the hematological and hematochemical profiles of athletic horses. Ten Standardbred and ten Italian Saddlebred mares were subjected to a 4-week training program after a seasonal rest, and hematological parameters (red blood cells-RBCs; hemoglobin-Hb; hematocrit-Hct; platelets-PLTs; platelet aggregation-AG; aggregation slope-Slope; fibrinogen-Fb), as well as Albumin (Alb) and non-esterified fatty acids (NEFAs), were analyzed. Blood samples were obtained each week during the training program following a simulated exercise performed at T0 and T4 (T0pre-T0post; T1, T2, T3, and T4pre-T4post). A two-way ANOVA revealed an increase in all assessed parameters post vs. pre at T0 and T4 (p < 0.01) and a decrease in PLTs (p < 0.01) at T0 and T4 in both breeds. A significant effect of breed was observed, with higher values for RBCs and Hb at each time point (p < 0.001); Hct at T0 post, T2, T3, and T4 post; and NEFAs (p < 0.001) at T0 post and T4 post in Standardbred compared to Saddlebred horses. Positive correlations were identified among RBCs, Hb, Hct, PLTs, Alb, and NEFAs in both breeds and between AG and Slope in Saddlebred horses. Negative correlations were identified among AG and RBCs, Hb, Hct, PLTs, Alb, and NEFAs in Standardbred horses and for AG and Slope with RBCs, Hb, Hct, and PLTs in Saddlebred horses. A comparable reaction to training was observed in both breeds following the seasonal rest.