Twitching is a
method used to subdue horses without the use of drugs. It is
frequently used for basic veterinary procedures such as passing a
nasogastric tube in a colicky horse. Some handlers will also use it
when working with a sensitive horse for things like clipping a
ticklish area or sheath cleaning. The goal is to make the procedure
safer for the horse and humans involved by restraining the horse.
Unlike drugs used to calm horses, the effect ends almost immediately
after the twitch is removed; no groggy recovery time afterwards.
methods used to twitch horses. The most common is a lip twitch where
the horse’s upper lip is squeezed in a device. Veterinarians often
use a rope twitch—sometimes called a hickory twitch– which is a
small loop of rope on the end of a long wooden handle. This twitch
typically requires one person to hold the twitch while another person
is performing the procedure. The video below shows how a rope twitch
A one-man twitch
uses essentially the same mechanism, but is a smaller device that
clamps on the upper lip, then held closed with a clip or an attached
rope that can be clipped to the halter and therefore doesn’t
require a second person.
Another method of
twitching is an ear twitch. This doesn’t use a separate device, but
is simply a firm hold applying a slight twist to the ear.
The mechanism by
which twitching subdues horses isn’t entirely understood.
Researchers at Brown University sought to find out more about how lip
and ear twitches work. The abstract of their study was published in
the September-October 2016 Journal of Veterinary Behavior.
Using a group of 12
geldings, the researchers measured heart rate, heart rate
variability, and salivary cortisol levels before and after
application of the twitch. An increased heart rate is a possible sign
of stress or pain while an increased heart rate variability—the
change in interval between heartbeats—is a sign of reduced stress.
Elevated cortisol levels are also a sign of a stress response. The
aim was to determine stress and pain levels.
The lip twitch
caused a decreased heart rate and increased heart rate variability
when applied for five minutes, but an increased heart rate and
decreased heart rate variability when used for a longer period. There
was no significant change in salivary cortisol levels. The
researchers say this indicates that the lip twitch subdues horses
through a calming, possibly pain-killing effect, but that the effect
may be reduced after the first five minutes.
The ear twitch
caused horses to have an increased heart rate and decreased heart
rate variability regardless of duration. The salivary cortisol levels increased
significantly. This suggests that the ear twitch causes a stressful,
and likely painful, effect.
While restraining a
horse on the fly when no lip twitch is available may sometimes be
necessary to prevent an agitated horse from hurting himself or people
around him, this research provides some evidence that lip twitching
is a preferable method of restraint, when possible.
Twitching in veterinary procedures: How does this technique subdue horses?
Flakoll, B. et al.
Journal of Veterinary Behavior: Clinical Applications and Research , Volume 15 , 88
Leslie Potter is a writer and photographer in Lexington, Kentucky. www.lesliepotterphoto.com