A study in the November 2013 American Journal of Veterinary Research looked at the skin responses of horses when the skin on the thorax wall was stimulated. The thorax is the area between the horse's shoulders and hindquarters. The study was done at the McPhail Equine Performance Center associated with the Michigan State University college of Veterinary Medicine. Lead researcher was Cynthia M. Essig, DVM.
In a clever study, eight horses “volunteered” to wear 56 reflective markers on their sides. Special infrared cameras tracked the movement of the markers after skin stimulation with a stick wand. The cutaneous trunci muscles work to twitch and remove irritants like flies. They also can twitch with the stimulation of a rider’s leg or the touch of a crop. Most horses adapt to the stimulation provided by the presence of a saddle and girth or harness.
The research showed that skin movement induced by a touch of the wand used for stimulus on the top of the thorax was a localized response. This was not the same as a generalized twitch of the cutaneous trunci muscles. The maximal skin response tended to show up below the stimulus site.
Among the eight horses used, there were variations in sensitivity. This fits with practical horsemen’s experience. Some horses are touchy about the girth being tightened and others could care less. Some young horses handle a saddle being placed on their back with equanimity while others put on a great show.
Bottom Line: While this study may seem a bit esoteric, it could lead to improvements in training techniques for young horses and development of better saddles and harnesses to accommodate a horse’s innate skin reactions.
Deb M. Eldredge, DVM, Contributing Veterinary Editor