According to an Associated Press article which appeared in Horse Net News, a Florida horsewoman was killed when a horse she was longeing was spooked and dragged her into a tractor and mowing equipment.
The article states that the rope by which Annette Ward was longeing her Paso Fino gelding had become entangled around her waist and when he spooked and ran, she was dragged about 50 or 60 yards into a tractor and hay-raking equipment.
This tragic accident underlines the fact that you do not have to be riding a horse to be at risk of injury. In fact, statistics show that most equestrian accidents happen with the rider on the ground. Accidents can be as simple as getting your foot trodden on, or as serious as what happened to Mrs. Ward.
Using the correct equipment, using it properly and being aware of your surroundings, and how the horse is likely to react to those surroundings may not be enough to prevent an accident, but should at the very least lessen the chance of injury.
I won't go into the specifics of teaching a horse to longe, or the various exercises from which your horse can benefit, there are plenty of books and videos on the subject (see sidebar). What I will do here is to point out various safety issues, both for the horse and the handler that will lessen the chance of accidents and make longeing a pleasant experience for you, and an educational one for your horse.
The longeing cavesson is popular for longeing English horses. It's much better than a regular halter for the purpose, as it is specially designed to be closer fitting and to enhance communication between horse and handler. The extra straps are designed to keep it from twisting and possibly damaging the horse's eye and the metal noseband and attached rings allow more control and communication with the horse via the lunge rein. Care should be taken when fitting the cavesson to ensure that it does not slip around when the rein is pulled to one side or the other.
The longe rein, or longe line is the means by which the handler communicates with the horse. This is usually cotton web, at least an inch wide and at least 25 foot long. It has a a snap attachment to connect it to one of the metal rings on the noseband of the cavesson and nowadays often has a swivel to keep from twisting up as the horse moves around the handler.
The most effective way I have found to hold the longe rein when longeing is to take the rein in the hand closest to the direction the horse is going, passing the rein between the little finger and the one next to it and then up out between the thumb and the fore-finger (the same way English riders hold the reins). This allows the handler to give and take on the rein with the minimum of hand movement. The end of the longe rein should never be wrapped around the hand or body, but should be folded back and forth between the thumb and forefinger of the other hand, in sections about 18 inches long. In this way, if the horse should begin to pull away, the longe line can be played to the horse easily and safely one fold at a time.
The longeing whip is held in the same hand (the opposite one to the direction in which the horse is moving) creating a triangle consisting of the longe line, the whip and the horse, with the handler at the apex of the triangle. Gloves should be worn when longeing a horse, preventing painful burns if the horse happens to spook and pull the rein through the hands.
As the horse moves around, the handler should keep his attention on the horse and follow his movement by making a miniature circle inside the horse's larger one. The handler should not stand in the middle of the circle with his arm held straight above his head so he doesn't have to turn around with the horse, and the longe rein should not be allowed to droop to the ground and get tangled around the feet. The rein should be carefully played out and collected back in as the horse either cuts in on the circle or pulls to the outside, as they all do at one time or another, especially in the early stages of training.
With young horses, it is often wise to kit them out with protective legwear while working them, since their coordination and balance will be less than desirable. Bell boots can protect the front feet from being trodden on by the back feet. Polo wraps can protect all four legs from being "brushed" by the opposite leg, as can leather or neoprene brushing boots.
Surcingles, which can be leather or nylon, fit around the horse's girth and have d-rings attached are a valuable addition to your collection of longeing equipment for your horse. In addition to accustoming the horse to the feel of the girth and saddle, the surcingle can be used to attach side reins, which can accustom the horse to the feel of a contact on the reins.
Any horse will benefit from having a clearly defined working area in which to longe. From a safety aspect of course, a round pen with 6 foot panel sides is desirable. For a young horse, an indoor round pen, or a sectioned off area inside an enclosed arena, will keep the distractions to a minimum and allow the horse to focus his concentration on his handler.
But not everyone has round pens, covered or uncovered, and sometimes you just have to make do. One way of creating a quiet area in which to lunge your horse is to use a corner of the field or pasture and use jump stands and poles (or old barrels and poles, chairs and poles, whatever you have access to) to mark out a large square in which to work your horse. If your horse is determined to break away, this isn't going to stop him, but if he's working calmly, it will give him a visual reference of the working area.
By taking precautions, and using the correct equipment, your horse can get the maximum benefits from his longeing exercises with the least chance of accident or injury.