Associations of health status and conformation with longevity and lifetime competition performance in young Swedish Warmblood riding horses: 8,238 cases (1983-2005).

OBJECTIVE To determine associations of health status and conformation with competition longevity and lifetime performance in young Swedish Warmblood riding horses. DESIGN Cohort study and genetic analysis. ANIMALS 8,238 horses. PROCEDURES Horses were examined for health, conformation, and performance from 1983 to 2005, when they were 4 to 5 years old, and competition results from 1983 to 2012 were evaluated. Associations between conformation, health, and talent scores of young horses and longevity (years in competition) and lifetime performance were analyzed. Odds ratios of competing later in life among horses with joint flexion test reactions were determined. Genetic correlations between young horse health, conformation, and talent scores and longevity and lifetime performance were determined. RESULTS Good overall 4- to 5-year-old health, conformation, and talent scores for performance were phenotypically and genetically associated with greater longevity and lifetime performance. Good health was genetically correlated (rg = 0.3) to longevity and lifetime performance. Among conformation traits, body type and movements in the trot were most strongly associated with future longevity; these were genetically correlated (rg = 0.2 to 0.3) to longevity and lifetime performance. Intermediate-sized horses were associated with highest longevity and lifetime performance. Positive flexion test results were associated with lower ORs (OR, 0.59 for moderate to severe and 0.76 for minor reactions) of competing later in life, compared with no reaction, and were associated with lower longevity (0.4 years). CONCLUSIONS AND CLINICAL RELEVANCE Horses with good health and conformation at a young age had better longevity in competitions than the mean. Positive correlations suggested that improvement of health and conformation of young horses will enhance their future athletic talent and performance.