Skeletal growth rates of weanling and yearling thoroughbred horses

This study was conducted to determine normal rates of growth of different skeletal segments in the thoroughbred horse. Growth of body weight and eight skeletal segments (wither height, hip height, body length, knee to pastern length, hock to pastern length, shoulder to pastern length, width of chest, depth of girth) were monitored in 106 horses (60 colts, 46 fillies) during the period from 14 to 588 d of age. Body weight gains were slightly higher (30 to 40 kg) than previously reported values. Growth in wither height and hip height were similar to previous reports. During the period measured in this study hip height was consistently 2 or 3 cm larger than wither height. Growth patterns for wither height, body length, and shoulder to pastern lengths were similar to one another. Growth of the knee to pastern and hock to pastern segments reached a plateau at approximately 140 d of age, which coincided with the cessation of longitudinal bone growth. These data define skeletal growth patterns in the thoroughbred horse and are useful in determining the relationship between growth and the occurrence of orthopedic diseases in horses.