Shoeing and some trimming methods force a horse to bear all his weight on the hoof walls. This causes peripheral loading, along with negative effects on his comfort and movement.
The horse’s hoof has evolved so that all parts are used synergistically when he moves and loads the foot. The sole, bars, frog, walls and back of the hoof all work together — or are supposed to — when the he lands and puts weight on the foot. In a natural barefoot hoof, thanks to the elastic and supple makeup of the hoof capsule, the foot expands and flexes when loading, particularly when over uneven ground. The healthy barefoot hoof adapts to the terrain it is negotiating, and with every stride the horse takes, its mechanism works perfectly the way nature intended.
What is peripheral loading?
Shoeing, along with some trimming methods, leave the hoof walls long or higher than the sole, forcing the horse to bear all his weight on his hoof walls. This causes peripheral loading. Horses were never intended to carry their weight directly on their hoof walls. Even a barefoot horse that has been trimmed where the wall is removed to just above live sole is susceptible to peripheral loading, especially when housed on hard surfaces like wood floors, or worse, cement. He too is being forced to hold his entire weight on his hoof walls, and over time, the foot will lose concavity.
Negative effects of peripheral loading
Because the hoof is concave, peripheral loading causes tremendous tension on the bones inside the hoof capsule. A non-conforming steel shoe adds the most insult because it not only causes serious peripheral loading and tension, but does not allow the hoof to flex. This lack of expansion and flexion reduces blood flow into the foot, which impedes shock absorption and starves the blood vessels and nerves. The long term effects of this tension contribute to navicular changes like bone loss in the coffin and navicular bones. It also causes the development of bone spurs and lesions, inflammation of the bursas and coriums, calcification of cartilage and ossification of the bones.
All this pushes the horse further into moving incorrectly and loading the hoof improperly, which leads to more damage to the internal structures. When the connection between the epidermal and dermal laminae are weakened through toxic insults to the horse’s system, placing him in metal shoes and causing peripheral loading with no support under the internal structures forces his weight to push the internal structures down, tearing the two laminae apart. Supporting the internal bones and laminae with something like a clog or boots with pads can alleviate so much pain and suffering when a horse is experiencing a severe laminitic attack.
The importance of correct locomotion
The hoof was designed to land heel first. This type of landing contributes to over 80% of the shock-absorbing mechanics of the hoof, and ensures proper blood flow to the entire hoof. Peripheral loading causes the horse to land toe first, setting the hoof up for developing many of the pathologies we see today. When the hoof lands toe first, the deep digital flexor tendon slackens. Rather than experiencing a smooth sliding action over the navicular bone, the horse instead slams the heel down, which slaps the tendon into the navicular bone. Over time, this constant abrasive insult causes lesions and changes in the navicular bone and bursa, leading to pain with every step.
A poor diet with too much sugar from grains or grass causes inflammation inside the hoof capsule, particularly in the back of the hoof/heel region. Severe thrush is directly caused by poor diet and lack of movement — especially incorrect movement. The thrush infection causes pain in the horse’s heel and central sulcus of the frog, forcing him to land toe first in an effort to get off the painful caudal foot. This leads to a weak digital cushion, contracted heels, and more toe first landing. It becomes a vicious cycle.
Exceptions to the rule
Occasionally, there are situations in which an individual horse may need more hoof wall on the ground in order to be comfortable. Horses with soles damaged by founder, years of shoes, or being housed in small environments, will sometimes need their hoof walls left higher. In these cases, I highly recommend boots with pads, or placing the horse in an area of pea gravel that will support the internal structures of the hoof and allow him to find comfort.
Developing a heel first landing
One of the ways to determine if your horse is landing toe first is to take him into a firm sandy arena and watch as he walks forward. Do you see his foot kicking dirt in front of the hoof as it loads? If the answer is yes, then chances are your horse is landing toe first. Better yet, have someone videotape your horse in motion. Very rarely will you see a heel first landing in a shoed horse, or in a barefoot horse that doesn’t have a healthy, well-developed back of the hoof. In this case, lifestyle and diet are usually the cause of the problem. Horses are meant to move 24/7, at their leisure. Improper movement will lead to contracted and internally damaged hooves, and ultimately lameness.
In order to achieve a heel first landing, the horse must be allowed to live and eat as naturally as possible so he can grow and develop a healthy, well-connected hoof capsule. A healthy caudal hoof includes a well-developed frog, a large firm digital cushion, and strong lateral cartilages. Removing peripheral loading devices, such as metal horseshoes, is a start. Placing the hoof in boots with pads will make loading the back of the foot more comfortable, and begin the healing process. Locating a natural hoof care practitioner who can trim to the wild horse model, and is trained to assess each horse as an individual, will ensure greater success in eliminating peripheral loading and transitioning your horse to become comfortably barefoot.