Abstract
Horses are exposed to chronic prolonged stress throughout their active life spans such as frequent races and daily training (Passantino et al., 2005). Long distance endurance races induce a severe stress on endurance horses during competitive ride. Exercise, in fact, induce variation in plasma biochemical constituents (Chanoit et al., 2002). So, the study of effect of race on clinical, hematological and biochemical parameters which could give useful information to make the race horse such as good managed and super athlete. This study was conducted on 28 thoroughbred endurance horse to determine the clinical, hematological and biochemical alterations that affect those animals before and after endurance race. Clinical examination including measuring of the rectal temperature, heart rate, respiratory rate and capillary refill time of each horse was preformed just before and 5 min. after completing a 40 km race. Blood and serum samples were collected from each animal just before race and 5 minutes after end of the race. Whole blood samples were used for measuring of Hb, PCV, erythrocyic count, red blood cell indices (MCV, MCH, MCHC), total and differential leucocytic count , while serum samples were used for determination of total protein, albumin, globulin, glucose, BUN, creatinine, total bilirubin , AST, CK , GGT , Na , K , Ca and chloride. Our results showed a significant increase in all the clinical parameters and most of the hematological parameters (RBCs, PCV, Hb , WBCs) within 5 minutes post-race as compared with their levels before starting the race, while serum biochemical parameters showed a significant increase in all biochemical parameters except serum calcium and chloride levels which showed a significant decreases in their levels at 5 min. after race as compared with their levels before the race. It is important to notice that the majority of the parameters that were changed immediately after race were within the physiological range which mean that the well-prepared horses for such exercise do not need any additional mineral supplementation even in hot climatic conditions.

Key words: endurance horse,race,clinical and hemato-biochemical alterations