Follow these basic guidelines from the American Association of Equine Practitioners (AAEP) when bandaging a horse’s leg: 

1. Start with clean, dry legs and bandages. If there is a wound, make sure it has been cleaned, rinsed and dressed according to your veterinarian’s recommendations. 
2. Use a thickness of an inch or more of soft, clean padding to protect the leg beneath the bandage. Apply padding so it lies flat and wrinkle-free against the skin. 
3. Start the wrap at the inside of the cannon bone above the fetlock joint. Do not begin or end over a joint, as movement will tend to loosen the bandage and cause it to unwrap.
4. Wrap the leg from front to back, outside to inside (counterclockwise on left legs, clockwise on right legs). 
5. Wrap in a spiral pattern, working down the leg and up again, overlapping the preceding layer by 50 percent. 
6. Use smooth, uniform pressure on the support bandage to compress the padding. Make sure no lumps or ridges form beneath the bandage. 
7. Be careful not to wrap the legs too tightly, creating pressure points. 
8. Avoid applying bandages too loosely. If loose bandages slip, they will not provide proper support and may endanger the horse. 
9. Leg padding and bandages should extend below the coronet band of the hoof to protect the area (this is especially important when trailering). 
10. Extend the bandages to within one-half inch of the padding at the top and bottom. If there is a potential problem with bedding or debris getting into the bandage, seal the openings with a loose wrap of flexible adhesive bandage. 

Good Video on Basic Bandaging

Amore detailed video that shows bandaging different areas.

Also check out the Wound Care page after the product display for more information!

Good info on wraps from TheHorse.com...

When is it appropriate to bandage a leg or wound? If it is appropriate, what is the best material to use? There is a growing variety of commercial bandaging material available to the horse owner and veterinarian; in one major tack store's catalogue there are 11 pages devoted entirely to bandaging material and "leg apparel." Much of what is used boils down to personal preference, but there are some basic rules when bandaging. The first rule is that a poorly applied wrap or bandage--or some types of bandage material applied in the wrong situation--can do more harm than good.

A general theme that applies to all bandaging--from the simplest of shipping wraps to the most elaborate full-leg medical bandages--is that bandages can be dangerous if not applied correctly. Bandages with wrinkles or bunches are dangerous. If there is not an adequate thickness of "wrap" material under the bandage, it is dangerous. If the bandage is too loose, it is dangerous.

A bandage more frequently is applied too loosely rather than too tightly. When asked how tight should a bandage be applied, the obvious response is "not too tight." That's like being asked what does pumpkin pie smell like--a pumpkin pie, of course. Not a big help, right? A commonly used gauge of bandage tightness is to "thump" the bandage. A properly applied leg bandage, if you flick it hard with your finger, should resonate a sound similar to that obtained when "thumping" a ripe melon or pumpkin. This is still subjective, as one person's idea of a ripe melon might differ from another's and the sound can differ depending on the material used, but the general idea is that the bandage should be uniformly snug.

It is important to ensure that there is an adequate amount of padding under the bandage for wound and shipping bandages. This provides protection, distributes the forces applied by the outer bandage, and helps prevent localized constriction. Most commercial wraps consist of one-quarter-inch to one-half-inch thickness of a soft material that is of a sufficient length to make it around the leg three to five times. For a number of bandage applications, the leg wrap might be made from individual sheets of commercial "sheet-cotton" (the standard size of "sheet cotton" is 30" x 36"). The sheet cotton can be folded in a variety of ways to create a custom length fit to the leg, and should consist of a minimum of four to five individual sheets. The important thing is to take care in the folding and make sure that there are no "wads" or thick seams that could create points of pressure on the leg.

The paramount importance is to apply a well-padded bandage snugly enough (with absence of wrinkles) to prevent it from slipping. When a leg bandage slips, it might just annoy the horse. However, the worst case scenario is a bandage that slips so that it bunches and creates a pressure point on the back of the tendon. This occurrence can precipitate a so called "bandage bow" or tendon damage. A bandage bow can also be caused by a bandage that is too tight.

It is also important to prepare the leg properly. Before wrapping, clean the leg to remove any visible dirt and any cockleburs, either through grooming or bathing. However, never wrap a wet leg. The moisture from wrapping a wet leg can lead to a fungal infection. If grooming, always groom down and with the hair to allow the hair to lie flat.

Standing Bandages

The general standing bandage is the one that many performance horses have perfectly displayed on their leg for half of any given day--snug, clean, wrinkle-free, and thumping like a Miracle Grow fertilized pumpkin. These general-use bandages and wraps can be purchased or custom made as mentioned above. The main functions of these general bandages are to provide protection and support, and to cover various leg sweats, paints, liniments, or poultices. The support can help reduce any "stocking up" or wind puffs, but the actual "support" that is provided to the tendons and other leg structures is not as much as many think.

For example, if you think in specific terms of how much force or weight is carried by the tendons of the forelimbs, it is easy to question how much support a typical standing wrap and bandage can provide. The forelimbs of a horse carry 60-65% of the horse's body weight. For a 1,200-pound horse, this puts approximately 360-390 pounds of weight down a single forelimb (when only standing at rest in the stall!). There is a good reason that when a horse's leg is fully bearing weight, the flexor tendons and suspensory ligament on the back of the leg feel like tight cables and seem as hard as the cannon bone itself. But, when the leg is picked up and the same tendons and ligament are palpated, they are soft and floppy. When weight-bearing, the tendons do act as suspension cables, so to speak, and hold the fetlock up. If the superficial and deep digital flexor tendons, and most importantly the suspensory ligament, are transected by injury, the fetlock will drop to the ground.

In a 1992 issue of the American Journal of Veterinary Research, a paper was presented that evaluated the ability of three different types of general support bandages to reduce the strain placed on one of the sesamoidean ligaments. The research project involved inserting a small strain gauge in the ligaments of eight horses and measuring the normal resting forces applied to the ligament, then evaluating how the various wrap and bandaging materials affected the forces. In addition, both a ridged splint and a fiberglass cast were evaluated. It was determined that none of the three bandages significantly reduced ligament strain; the splint did reduce the strain, and the fiberglass cast, as would be expected, reduced the strain the greatest. The fiberglass cast needs to be applied by a veterinarian.

Wound Bandages

The primary functions of placing a wrap and bandage over a wound are to provide protection, place a clean environment next to the wound, and provide general support to the tissues surrounding the wound. In addition, the bandaging of lower leg wounds is generally thought to reduce the formation of exuberant granulation tissue, or proud flesh.

When a wound is in a high-motion area, such as over a joint, an appropriate wrap and bandage will create some degree of immobility that can prevent stitches from being ripped out. Bandaging these sorts of wounds can also improve the cosmetic and functional aspects of healing. These wraps and bandages are commonly referred to as "stack" or "stove-pipe" wraps and generally consist of two of the standing bandages "stacked" on top of each other. These wraps can be difficult to apply, especially to the hind leg, as the curvatures of the hock must be navigated. Applying the bottom wrap first and then applying the top will help both stay in position better. These wraps are prone to slipping with leg motion, and frequently employ the elastic and conforming properties of bandage material such as Vet Wrap or Elastikon.

With the full leg wraps and bandages, it is important to cut a small tension release in the outer layer of bandage just over the bony prominence behind the carpus and hock, as pressure sores can develop in those areas.

With a wound that cannot be primarily repaired or sutured (typically an older wound that has become infected or a wound that has lost a large amount of tissue), the type of sterile dressing applied directly to the wound depends on the stage of healing. The two major types of dressings are the adherent and non-adherent types. For wounds that are infected and producing a considerable amount of drainage or pus, the adherent type usually is chosen. The adherent dressing actually aids in the early healing process by helping debride the wound when the bandage is removed. When the wound bed becomes healthier with granulation, and the exudate or pus decreases, a non-adherent dressing is favored. An absorbent layer of clean bandage material is smoothly applied over both of these dressings, then all should be covered by a standing wrap and bandage.

Shipping Bandages

There is a plethora of commercially available protective shipping gear for equine legs--everything from the simple Velcro wrap for the cannon bone area to a full-length leg cover that is molded to go over the hock or knee. The choice of what to use obviously should take in the individual horse's needs, i.e., is the horse a solid shipper which has the travel experience of Captain Kirk, or does he come completely unglued and slip into self-destruct mode every time he hears the trailer ramp let down?

In my opinion, if the veteran shipper is going to injure something, it is usually the coronary band or heel area from a bad cross-step on a bumpy road or too quick a start, stop, or turn. Yes, they can injure anything else that gets in the way, but this area is most vulnerable--especially if the horse is wearing shoes, and even more so if the shoes have toe grabs, heel grabs, or other traction devices. Also, coronary injuries can be particularly painful and can cause lameness that might prohibit the horse from doing what you wanted to at the end of the ride (horse show, trail ride, etc.). In addition, damage to the coronary band area can result in a permanently abnormal hoof growth in that area that can cause long-term problems.

Bandaging and/or the use of bell boots can help prevent or at least lessen the severity of coronary band injuries--if they properly cover the area. That's the big if. I see many horses shipping in and out of places with exceptionally well-applied bandages that stop just below the fetlock and leave the coronary area wide open to attack from the other foot. But if bell boots are used, they must be the appropriate size. I have seen many coronary lacerations occur despite bell boots in part because the boot was too large for the foot and did not cover the coronary band in the area of the heel.

My personal preference is to use the commercial "pillow" or "quilted" type wraps that are the appropriate length for the leg and are of good enough quality to provide thick padding. The material should extend from just below the carpus or hock to over the coronary band by one inch. My preference of bandage material to apply over the wrap is commercially available flannel that is six inches wide and 10-14 feet long, depending on how long the horse's legs are. Many people make the flannel bandages themselves out of bulk flannel material available at almost any fabric store.

If the horse requires more extensive protection, many of the commercially available "full" leg shipping boots work well. In most cases, this will be in an effort to protect the hock of a chronic kicker. It is very difficult to bandage the hock so that the bandage stays in the proper position and does more good that harm. It is important, if a hock bandage is going to be used, that it fits the hock/leg well and is secured adequately to prevent slipping. In addition, hock bandages might make some horses kick even more. If this happens, even the best of bandages is no match for the forces created by a kicking horse. If kicking continues, remove the bandage and train the horse to stand with bandages on.

In addition to the protective hock gear, padding the back and/or sides of the shipping stall can be extremely beneficial; there are many sources of commercial "kick" padding available. It is important to double check padding to ensure that it will not fall under the horse in transit and frighten the horse or become ineffective protection.

These are my personal preferences. They are a product of what has worked for me and my mentors in the horse industry and do not (directly) reflect any particular superiority of materials. The important points, regardless of material used, are that the wrap and bandage or other leg protection fit the leg well and are adequately secured without a chance of slipping or bunching.

One Last Note

Legs are not the only part of a horse's body that are bandaged; the tail is frequently bandaged for a variety of reasons, most of them associated with reproduction-related events. Although it might seem relatively harmless to apply a bandage to a horse's tail, it occasionally results in a particularly nasty complication. If an elastic material is used, it is easy to apply enough force to restrict blood flow in the tail. In addition, some of the commercial elastic bandage materials can shrink after getting wet and drying. This can cause blood flow problems even if the original bandage was not applied too tightly. The overall effect of this constriction, if allowed to go on long enough, can be the death of the lower part of the tail and the subsequent need to amputate that part of the tail.

Care must be taken when applying a tail bandage as the absence of padding under it makes it much easier to apply it too tightly. If the bandage is to be left on for a significant amount of time, it should be monitored to ensure that it does not become too tight or bunch up and cause constriction.

Keeping in mind these bandaging considerations will ensure that the next time you have to wrap your horse's leg (or tail), the bandage has the beneficial effect you intended.

The following information is provided as a courtesy and service to the horse industry by the American Association of Equine Practitioners.

There may be any number of occasions when you will need to bandage your horse’s legs. Bandaging can provide both protection and support for the horse while working, traveling, resting or recovering from an injury.

Regardless of the purpose, it is essential that you use proper leg bandaging techniques. Applied incorrectly, bandages may not only fail to do their job, but also may cause discomfort, restrict blood flow and potentially damage tendons and other tissue.

It is often said that it is better to leave a horse’s legs unbandaged than to bandage them incorrectly. Fortunately, there is nothing complicated about learning to apply bandages. It simply takes the right materials and a bit of practice. If you have never bandaged a horse’s legs, ask your veterinarian to demonstrate the proper techniques. Practice under his or her supervision before doing it on your own.