In order to find early selection criteria to improve the longevity of show jumping horses in competition, a specific protocol was constructed. Before entering competition, young horses were measured for many traits. These horses were offspring of two groups of sires selected as having the highest and lowest estimated breeding values for functional longevity in jumping competition, as calculated from progeny. Functional longevity was defined as the time spent in competition corrected for the level of performance. The dataset included 952 horses (mainly French Saddlebred) and 77 blood parameters. Heritability was estimated using a mixed model including the effect of age, sex, place and date of collection, weight and animal random additive value with 10,280 horses in pedigree. Heritability of blood parameters was generally moderate to high: 21 values were higher than 0.5 and 39 were between 0.2 and 0.5. The most heritable traits were hematology and enzyme traits: mean corpuscular volume (0.90, se 0.11) and mean corpuscular hemoglobin concentration (0.92, se 0.11) but also traits as liver isozyme (0.72, se 0.13) or total alkaline phosphatase (0.68, se 0.12), small lymphocytes (0.67, se 0.13), superoxide dismutase (0.60, se 0.11). Logistic regression to predict the group of sires favorable to longevity revealed significant effect of lower mean corpuscular hemoglobin concentration (pvalue < 0.001), lower quantity of leukocytes (pvalue<0.01), lower quantity of liver isozyme of alkaline phosphatase (pvalue<0.05), higher relative proportion of a2-globulin (pvalue<0.001) and a1-globulin (pvalue< 0.05), lower relative proportion of monocytes (pvalue<0.05). Blood parameters measured at rest at young age might be predictive of genetic value for functional longevity in jumping.