Sometimes lameness can be brought on by a complex and serious cascade of events such as with laminitis, but at other times the lameness is the result of something that seems minor – like a stone bruise. This rather innocuous injury can have its own complexity and, if left untreated, can result in a horse's demise.
The bruise referred to here affects the sole of the horse's foot. A bruise can result from a variety of factors – ranging from a step on a stone causing an external bruise to landing with such concussive force when going over a jump or racing across a hard surface that the bones of the inner foot bruise the inside of the sole.
Some bruises come and go with little notice. Fitting into that category, says certified Journeyman Farrier Doug Butler, are bruises that can occur from the buildup of snow in the bottom of the foot during the winter months. On the other side of the spectrum are bruises so severe that they not only produce lameness, but also result in an abscess that can compromise the health of the entire foot if left untreated.
Sole of the Matter
When it comes to the construction of hoof soles, says Butler, not all horses are created equal. Some have tough soles that defy bruising, even in rocky, rough terrain; others have thin, sensitive soles that bruise easily.
In the latter category, says Butler, are quite often Thoroughbreds and Warmbloods that are related to Thoroughbreds. The reason for thin soles in some of these horses must be laid at man's doorstep because of breeding practices, he explains.
Thoroughbreds, for example, have been bred for speed for many years. Often, other highly heritable qualities--such as good, solid hooves--have been ignored in the quest for that elusive quality. In many cases, these thin-soled horses are able to exist and perform with few problems because they are exercised on smooth surfaces that are devoid of rocks and other sharp objects. However, when they are placed in an environment where they must travel across a rocky surface, their feet often are unable to cope. Stone bruises and lameness are the result.
Shoeing for Protection
In many cases, Butler says, keeping a thin-soled, shelly-walled foot sound involves wider-than-normal shoes, bar shoes, or shoes with pads. While special shoes and pads can provide an assist for the thin-soled horse, Butler says, care must be taken that the remedy doesn't produce more aggravation than relief.
For example, if the amount of padding between the sole and the ground causes pressure on the sole, the condition will be aggravated every time the horse sets a foot on the ground.
In some cases, Butler notes, farriers trim a foot too short before adding a pad, which can result in more aggravation than relief. The goal with a thin-soled horse should be to pare out almost none of the sole when trimming or shoeing.
Another goal, Butler says, should be to avoid making the horse "pad dependent." If a pad is kept on the foot constantly, he says, it can result in a sole that is even weaker than it was when the pad was first applied.
Stone Bruise Gone Bad
When a stone bruise is left untreated, the result can be an abscess. Normally, says Butler, an abscess can be extremely painful to the horse. If left untreated, it can cause permanent damage to the inner foot.
When a bruise occurs, he explains, blood vessels within the foot are damaged, which often causes leakage of blood and serum into the tissues. This can cause an abscess. The natural function of the foot can exacerbate the problem, he says. For example, when the foot is damp, it tends to expand and the door sometimes is opened to bacteria via the white line. When the foot becomes dry, it contracts and invading bacteria wind up being trapped within the foot where they proliferate and the abscess forms (or if already formed, worsens).
When an abscess is discovered, the goal is to get it to drain, says Butler. Often the drainage tract will be through the coronary band. To facilitate this process, the foot can be soaked in water containing Epsom salts.
However, there are cases where invasive assistance is required. Some farriers and veterinarians favor paring out the sole where the abscess is located until it is reached and allowed to drain.
A better way, in Butler's opinion, is to attack from the side--through the hoof wall. When the invasion is through the sole, he believes, healing time is prolonged and there is the ongoing problem of keeping harmful bacteria from entering the foot through the opening.
When the abscess drains, Butler says, the horse normally experiences instant relief and, unless there has been serious paring away of the sole, can quickly resume training or work. This is particularly true of the abscess that resolves itself by erupting and draining through the coronary band.
Take-Home Message
A thin-soled horse that receives ongoing foot care can become and remain a useful mount, but it is much easier to avoid bruising with a horse that has naturally thick, tough soles.
