Reprinted from The Horse Report with permission from the Center for Equine Health, School of Veterinary Medicine, University of California, Davis (UC Davis). 

Transport stress has long been thought to predispose horses to respiratory disease. The stress response during transport causes changes in serum cortisol concentrations, heart rate, immune parameters, and serum muscle enzyme activities. Another variable in the transport of horses—cross-tying—has been the subject of concern to UC Davis Center for Equine Health researchers.

While cross-tying horses individually in stalls is common practice for transporting show and race horses, horses also travel in small groups or individually without being restricted by tying.

Carolyn Stull, MS, PhS, and Anne Rodiek, MS, PhD, recently conducted a study to examine the specific physiological responses of horses during transport to either cross-tying or traveling loose. They found that the cross-tied horses had larger increases of selected stress parameters 24 hours following transport than did horses traveling loose without being tied. In particular, they found that levels of serum cortisol, which is secreted during stressful situations, were greater in the cross-tied horses, although the levels returned to normal following transport