Experimentation with laboratory animals, encompassing the range of usual species (mice, rats, cats, clogs, and primates), has conclusively demonstrated that handling by humans during early life facilitates subsequent development in terms of health and viability, reduced emotional reactivity, more adaptive responses to a variety of stressors (both biological and behavioral adaptations), and increased ability to adapt to changing circumstances as exemplified by increased ability to learn and solve problems (seeM. Bornstein 1985, for recent review).
Two studies (described below) (Heircl et a!. 1981; Whitaker 1982) conducted at Texas Tech University (TTU) have extended these findings regarding the beneficial effects of early handling from laboratory animal species to domestic horses. The findings (reported below) suggest that a moderate amount of handling of young horses increases their learning ability as measured by maze-learning tasks and estimates of trainability under saddle, decreases the stress (both for horses and human trainers) associated with confining and training the horse under saddle, and possibly, reduces attrition during the initial years of rearing. This latter result is suggested by our data. More extensive sampling is necessary before it can be stated as a conclusion.
Heird, J.C., Bell, R.W., & Brazier, S.G. (1986). Effects of early experience upon adaptiveness of horses. In M.W. Fox & L.D. Mickley (Eds.), Advances in animal welfare science 1986/87 (pp. 103-109). Washington, DC: The Humane Society of the United States.