The twitch is a tool that is used to control horses undergoing veterinary procedures and mares when they are being bred. During the recent American Association of Equine Practitioners' convention in San Antonio, Texas (The Blood-Horse of Dec. 9, page 7868), Dr. Sue McDonnell of the University of Pennsylvania discussed how the twitch can be employed in a more effective and humane manner.
The twitch provides minimal restraint, she said, and it also is mildly aversive, directing the horse's attention away from veterinary or breeding shed activity. Application of the twitch also results in the release of the horse's endogenous opiates, which have a calming effect.
Circulating beta-endorphin levels rise steadily for about three to five minutes after the twitch is applied, then reach a plateau that lasts for a variable length of time, depending on the horse. Next, there is a steep decline in beta-endorphin levels, when the horse will start to show signs of agitation. The animal eventually will reach "what we call the 'blow stage,' when it will 'blow' the twitch and try to get away from it, no matter what you do," McDonnell said.
Some horses reach a point where they do not tolerate the twitch well at all, but such reactions can be prevented, according to McDonnell. A specialist in equine behavior, she provided the following recommendations for establishing and maintaining twitch compliance:
- Respectful application. The person handling the twitch should be calm, confident, nonconfrontational, and unhurried. "I think a fair number of horses have a bad first twitch experience because we are sending them all sorts of signals that a really scary, dangerous event is coming up," she said. "With our brusque, hurried manner of getting the twitch on, the horse is getting the message that something terrible is about to happen."
- Maintain appropriate tension. "I have a very hard time teaching this," McDonnell said. "The best result I have had is by having people watch the angle of the horse's neck. When the horse throws its head and its ears go back, it's time to relax it (the twitch) a little bit."
- Monitor responses. The response pattern of an individual horse to a twitch is usually consistent, unless the animal is extremely aroused or upset. "Be aware of those behavioral responses, monitor them, and respect the limits of the analgesia," McDonnell said.
In addition, McDonnell recommended that horse owners introduce their animals to the twitch before it is needed, so they and their animals will be calm and relaxed, avoiding a negative experience that could have long-term consequences.