Few occurrences are more disturbing to a horse owner than lameness. A lame horse is one that is idle in a stall or paddock instead of being enjoyed in the show ring or on the trail. 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 Doug Butler, PhD, Certified Journeyman Farrier, Fellow of the Worshipful Company of Farriers, of LaPorte, Colo., are bruises that can occur from the buildup of snow in the bottom of the foot during the winter months. Butler is widely known as a lecturer on hoof care and shoe making and fitting, as well as the author of the classic book on farrier science Principles of Horseshoeing I and II.
The first detection of a mild bruise from balled up snow, says Butler, often comes when the horse's feet are trimmed in the spring and the farrier notices a reddish spot or area where the bruise occurred. In such cases, the bruise would have caused tiny blood vessels to rupture, but would not have created pain to the point that the horse was lame.
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
To begin with the basics, it should be pointed out--as Butler and other researchers have made clear through the years--that the sole of the foot is not designed to be a primary weight-bearing agent. That job is left up to the walls of the foot, which are thicker and constructed in a conical shape. The hoof wall is designed to tolerate the bearing of the animal's weight with each step it takes.
The convex sole is designed to serve as support and protector for the inner structures of the foot, starting with the sensitive inner sole and including the bones and circulatory system that carries nourishment-bearing blood to all parts of the inner foot.
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 called speed. 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.
A case in point: When living in Kentucky, we began competing in horse trials. My mount of choice was a solidly constructed 16.1-hand Thoroughbred gelding that had competed on the track. He sustained a severely bowed tendon in his three-year-old year that ended his racing career. In fact, it nearly ended his life. The "bow" was so severe that consideration was given to putting the horse down. A young veterinarian said he would like to experiment with a tendon-splitting procedure that had originated in Sweden. The horse was given to him, the treatment worked, and the horse was trained for eventing.
Eventually, the horse came into my possession. He had a heart as big as all outdoors, and while he hated the dressage routine, he jumped fences on the cross country course and within the stadium with great gusto.
The tendon splitting procedure was a total success, and the horse never took a lame step because of it. However, it was obvious from the outset that he had rather shelly hoof walls and weak, thin soles. By keeping him shod and performing on yielding surfaces, we had no problems.
While competing at horse trials was fun, our true love through the years has been trail riding. The big gelding was a natural fit as a trail horse. He loved it out on the trails in places like Harrison-Crawford State Forest across the border in Indiana. I decided that he would be my horse of choice for our annual treks to the mountains in the west. The rocky trails took their toll and, in order to prevent sole bruising, we had to cover his soles with pads.
It was an ongoing problem with no permanent cure in sight. He had to be re-shod with some frequency, and the flaking walls of his feet often crumbled and gave way. We resorted to glue-on shoes that helped for a time. By hook or crook, our efforts, combined with those of farriers and veterinarians, managed to keep him usable until he was about 18 years of age, when his hooves literally gave out and he had to be put down.
The experience with this big, gallant Thoroughbred is recalled here to make the point that there are a good many horses in the equine world just like him and, as Butler will say, special care must be taken with their feet to keep them sound and usable.
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.
"This can be especially true when some forms of plastic material are used in pad construction," Butler notes. "A plastic pad can cause the foot to sweat, with the moisture serving to further weaken the sole."
Thrush can also become a problem if bacteria are able to invade the foot and flourish in a dark, damp environment. One of the best ways to prevent thrush, according to Butler, is to use a form of antiseptic packing between the sole of the foot and the pad.
A packing that uses peat moss and pine tar, he says, can help cushion the sole and prevent bacteria from setting up shop.
A packing substance of choice for some time was silicone, but there have been some negative side effects, he says. When it came into contact with sensitive outer layers of the foot, such as around the
coronary band and bulbs, silicone had a tendency to irritate the skin.
In that regard, he explains, it is a bit like turpentine, which can be effective in killing thrush-causing bacteria but also can "burn" skin.
Sometimes, Butler says, it can be helpful to the horse if only a partial pad is applied to the thin-soled foot. In this instance, the pad extends inward from the shoe toward the center of the foot on all sides, but there would be an opening in the middle that allows air to circulate. Thus, the weak sole would be protected, but it would not be totally sealed off from the environment.
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.
To this point, we have discussed horses with thin soles, such as Thoroughbreds and Warmbloods. What type horses would tend to have thick, strong soles?
"Look at photos of some of the cavalry horses in years gone by," says Butler. "They aren't the prettiest, but they have big, strong feet with tough, thick soles."
Many horses reared in the West today have the same type of soles, says Steve Mellin, Certified Farrier, who heads the farrier program at Colorado State University (CSU) and is responsible for trimming and shoeing the many horses in the university's reproduction department.
While stone bruises might be a problem among Olympic-level equines, their more humble brethren, many of which are used as embryo recipients at CSU, rarely have a stone bruise problem, according to Mellin. Many of these horses spent their early years in an arid climate, traveling over rough ground, he says, and as a result--because of both genetics and environment--developed strong, tough soles.
Horses that hail from areas with more rainfall and frequently travel over soggy ground often will have weaker soles, Mellin believes, but a counter-balance is that these horses do not expose the soles of their feet to hard, sharp objects as do the horses of the West.
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.
About the Author
Les Sellnow is a free-lance writer based near Riverton, Wyo. He specializes in articles on equine research, and operates a ranch where he raises horses and livestock. He has authored several fiction and non-fiction books, including Understanding Equine Lameness and Understanding The Young Horse, published by Eclipse Press and available at www.exclusivelyequine.com or by calling 800/582-5604.
POLL: University Equine Hospitals