Growth of Twin Quarter Horses

Equine twins that survive gestation and the first few days postparturition are relatively rare, and growth data for equine twins are missing from the published literature. Documentation of the growth and developmental patterns of equine twins should be helpful in establishing expected rates of growth and in evaluating nutritional and management protocols best suited to equine twins. Weekly body weights were recorded on Quarter Horse twins over a span of approximately 640 days, and both body weights and average daily gain were compared to singleton Quarter Horse foals and standard growth curves. Average daily gain measurements showed a steady increase over the 640-day period, suggesting that the twins were undergoing catch-up growth. It is of particular note; although not surprising, that the twins do not follow any of the predicted growth curves. The frequency of measurements allow for a high-resolution perspective on short-term changes in the rate of gain and highlight the potential for further research on the normal patterns of equine growth. The data presented here are a unique study of the early growth pattern of equine twins.