How to break a mouthy colt from biting or nipping?
There are several approaches to the problem of "mouthy" colts that want to bite at you. However, the first thing to remember is that this is a normal behavior in colts. This is how they interact with each other and determine who is the boss. The easiest way to combat the problem is to castrate the colt, which removes the main source of testosterone, the male hormone that is responsible for stallion-like behavior. Biting usually is greatly reduced after castration, and geldings usually make more steady riding horses than stallions. If castration doesn't completely correct the problem, you may have to punish the horse when it bites. A sharp whack on the muzzle when the horse tries to bite will usually get the message across. Make sure you are consistent if you must use punishment. Never allow the horse to even try to bite without letting it know that biting is unacceptable behavior. If castrating the colt is not an option, there are several other things you can do to reduce this behavior. If possible, turn the colt out with other horses. Interaction with other horses will help him learn that biting is not always appropriate and will let him burn some energy so he is more willing to pay attention to you when you are working with him. When you do work with him, make him pay attention by keeping his mind occupied with various turns, starts, stops, backing up, etc. Require the horse to respond immediately to your signals and keep him too busy to think about biting. An option that some handlers use is to punish the horse by squirting lemon juice in his mouth when he tries to bite. The plastic lemon-shaped squirters found at most grocery stores work well. Another option is to give young stallions an appropriate "chew toy," such as the butt end of a crop while leading and grooming the horse. This lets the horse express its natural behavior in a way that does not hurt you, but it also allows the horse to become somewhat inattentive to the handler. Hopefully, one of these methods will work in your situation. Probably the most important thing is to make sure you are consistent in letting the horse know that biting you is not appropriate. In colts, there is really no such thing as a "playful nibble" because they will rapidly begin to think that biting is acceptable.