The risks and benefits of using boots or bandages on horses’ legs *H&H Plus*

  • Are boots or bandages better for leg protection? Professor Roger Smith FRCVS and Professor Michael Schramme weigh up the pros and cons in this week’s Vet Clinic

    Most horses are routinely booted up or bandaged for exercise. While some kind of protection is largely seen as essential, there are benefits and risks in covering or inadvertently constricting the lower limbs.

    A common misapprehension is that bandages act to “support” the limb by preventing over-extension of the fetlock. A well-applied layered clinical bandage can provide some such support in foals or very small ponies, but studies have found that this is not the case with an adult horse.

    Achieving this requires the application of more rigid materials, such as a splint or fibreglass cast, or orthotic boots (EqueStride or FastTrack, for example). These newer boots can be used while the horse is at pasture or even being ridden, but they are not insubstantial and are intended for injury convalescence rather than routine use.

    A simple cloth bandage applied to the cannon region – a so-called “exercise bandage” – obviously provides no support to the fetlock joint, as it does not cover it. It is sometimes claimed that exercise bandages support the flexor tendons, but it is difficult to imagine how. The superficial digital flexor tendon undergoes a peak load in excess of one tonne during exercise, so surrounding it with a bandage will have no influence.

    That said, an exercise bandage or boot can guard against external trauma, which typically occurs due to an over-reach – when a hind foot strikes the back of a forelimb. This blunt trauma can be massive, causing substantial tendon damage. A cloth bandage is unlikely to offer much protection other than against the lightest of blows, but rigid boots can be life-saving.

    Limb coverings may also help with a horse’s proprioception. This is the part of the nervous system that tracks where the limbs are at any given point during movement, to coordinate locomotion effectively. It is thought that bandages might offer sensory “cues” to improve coordination, which can be helpful – especially when the horse is tired.

    Swelling of the legs is common, especially in the hindlimbs, because of the physics related to the length of the leg, the effect of gravity and the slow movement of blood back up the limb. Bandaging legs for work will not help, since limbs tend to swell when the horse is not moving, but applying bandages in the stable can be effective in reducing or preventing puffiness.

    Pressure and temperature

    While a degree of pressure is needed to keep an exercise bandage in place, it is essential that this pressure is not excessive. The bandage must be applied evenly, with correct tension, overlapping each turn of the bandage by between a third and a half of its width. The addition of sufficient padding underneath can lessen the risk of over-tightening.

    Otherwise, bandage sores (affecting the skin) or bandage bows (affecting the underlying tendon) can occur very quickly. This is a real risk for an exercising horse, due to the extra movement in the limb.

    A bandage or boot can increase the temperature inside the flexor tendons and the suspensory ligament. The superficial digital flexor tendon in particular generates heat during exercise, because of repeated cycles of stretch and relaxation during normal locomotion. You can appreciate this effect if you rapidly stretch and release a thick elastic band before holding it to your forehead.

    The temperature inside the tendon can exceed 45°C during intense periods of exercise. This rise in temperature is counteracted by the flow of blood through the tendon and the cooling effect as the limb moves through the air. A bandage will limit the cooling effect, however, and if too tight, can even reduce blood flow through the tendon.

    The effects of temperature rise are not completely understood, but research in the tendon biology lab at the Royal Veterinary College has shown that short periods of hyperthermia (raised temperature) can induce apoptosis – programmed cell death – and therefore could have a deleterious effect on the tendon.

    Interestingly, short spells of hypothermia (cooling) after hyperthermia have been shown to be protective against this cell death. This observation provides scientific support for the already established procedures of cooling equine limbs after periods of intense exercise.

    It also makes sense to use boots that are vented to allow air to circulate around the tendons, or to remove bandages as soon as the exercise is completed so that cold water or cooling products can be applied to the limbs if necessary.

    Complete removal of loading from a tendon, such as that achieved by cast immobilisation after injury, will result in bone and tendon weakening and may induce tendon laxity and some fetlock sinking after the cast is removed, particularly in young, growing animals. Because of the inability of exercise bandages or boots to “unload” a tendon, however, the benefits of normal loading – necessary for tendon health – are unlikely to be adversely affected by their use.

    Assess the risk

    The choice of boot or bandage should be made depending on the likely risks posed by the specific type of exercise in which the horse is engaged. Any activity that increases the potential of external trauma, such as eventing or showjumping, warrants a robust covering.

    Boots can carry more weight than bandages, but are more protective because they tend to be made of thicker material. Given that physical protection would be a key property, they should be tough but also lightweight – to minimise the energetic cost to locomotion – and adequately pliant so as to avoid direct trauma to the skin and underlying structures by the boot itself.

    Recent innovations in boot construction have sought to maximise protection and comfort while minimising weight and water absorbency, using materials such as Kevlar, carbon fibre and neoprene.

    Although elasticity in a material might be considered important for flexibility, increasing the stretch during application can increase the risk of a boot strap or bandage becoming too tight.

    It remains important to consider carefully why you are using any kind of leg protection, so that a risk-benefit assessment can be made. The application of boots and bandages may be an established and routine part of equestrian sport, but there is still much to learn about their effects.

    Further research will continue to provide scientific information, helping us to make the right choices.

    Smart boots

    In a world of increasing miniaturisation and advancing digital technology, tack and accessories have the potential to play a proactive role in horse health.

    Boots can be instrumented to provide data that may prove useful for the diagnosis, monitoring and prevention of injury. An example is the Ekico boot , which measures gait asymmetry via pressure sensors to compare fetlock function at key points of the horse’s stride: the attack phase, the swing and the push-off. The boots also record the surface temperature of the limb, which may have relevance to hyperthermia.

    Since the early identification of locomotion problems tends to improve outcome, products such as these “smart boots” could be beneficial in detecting lameness before it is visible to the eye. This type of wearable technology is currently in its infancy but could eventually become part of a horse’s everyday wardrobe.

    H&H 13 August 2020

    About the authors

    Professor Roger Smith FRCVS, a professor of equine orthopaedics at the Royal Veterinary College (RVC), is a surgeon within the college’s referral hospital and also directs research into equine tendon disease. rvc.ac.uk/equine-vet; rvc.uk.com/equine-stem-cells; 01707 666272.

    Professor Michael Schramme spent many years working at the RVC and is now based at the University of Lyon, where he specialises in equine surgery and lameness. The benefits of standing surgery

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