Though the equine hoof is a marvel of resiliency, it's not made of rubber, titanium or steel. It's a living organism that has its vulnerabilities, and when faced with unusual stresses, it shows them.
Stone bruises are one of the most common signs that the hoof has taken some abuse. They appear as reddish purple (on a white hoof) or dark gray (on a dark hoof) spots, sometimes visible on the soles of your horse's feet, especially just after the farrier's knife has removed the surface crud. But usually by the time you spot the bruise, it can be several months old.
Typically, stone bruises aren't serious and some horses seem to be able to ignore them better than others. When these injuries are fresh, they may cause minor lameness. But if a stone bruise happens right before an important competition, it can be a crisis. And if your horse shows a predilection for repeatedly bruising his soles, it's a chronic problem that you'll want to solve.
How Stone Bruises Develop
Stone bruises generally are the product of your horse's environment. Traveling on hard, rocky ground can batter your horse's soles, especially if he's used to more manicured conditions. But a hard knock against a solid object – a fence rail or a tree root, for instance – can have the same effect.
So can shoes that are too small, or those equipped with caulks, grabs or trailers that alter the foot's natural flight path. Hooves that grow up and around a shoe that has been left on too long also can bruise, particularly if the shoe is loose and bangs on the sole with every step.
Certain types of feet seem to be more vulnerable to bruising than others. The classic battered hoof has a flat sole and thin walls – a conformational fault seen in many horses with thoroughbred breeding. A horse with soft feet – common on the wet and rainy West Coast of North America – may be likely to bruise if he's ridden on firmer ground, but a horse with hard, dry hooves also may be a bruising candidate because his foot has less natural 'give' than most. Small, upright feet, especially those designated clubfeet, can gather more than their fair share of bruises too.
Diagnosing Stone Bruises
So if a stone bruise isn't visible for a month or more, how do you diagnose a fresh bruise?
"Finding them is largely a matter of experience and gut instinct," says certified journeyman farrier Wes Goff of Canada. "A horse whose feet appear to be sensitive without any other obvious cause often has a stone bruise – and I suspect it especially if the horse has a flat foot or thin walls. I ask about his history too: where has he been ridden recently, and what has he been doing.
"I can usually differentiate a stone bruise from a brewing abscess by the feel of the sole. If it's soft, mushy or is carrying heat, or if the horse is very sore, I start thinking abscess,' while a stone bruise is more subtle," explains Goff.
Treating Stone Bruises
There's not much you can do to treat a sole bruise, says Goff, other than rest your horse if he's sore and take care not to ride him on punishing ground.
Generally the sensitivity will dissipate in a few days. But if you're in dire straits and need your horse sound immediately, you can consider using a sole-numbing paint, such as Sole Freeze, that will allow your horse to perform pain-free for a few hours. The active ingredient in these paints is phenol, which Goff says you can buy directly from any well-stocked drugstore. Because phenol is fairly corrosive to skin, however, you'll want to wear gloves when you apply it – and be sure to keep it securely capped and well out of the reach of children.
Protection and Prevention
If your horse seems prone to stone bruises it may be time to consider some shoeing changes to minimize the time he spends languishing in his stall instead of being ridden.
There are dozens of designs of hoof pads on the market, from basic leather, to various plastics, to amazing high-tech shock-absorbing pads that, while cleverly designed, are expensive and may provide so much flex that they cause shoes to pop off prematurely. Goff has had his best results with ordinary plastic pads that are affordable and easy to shape. A squirt of silicon packing underneath the pad helps 'seal' the area between the foot and pad and prevent thrush from sprouting in the damp places you can no longer reach with your hoof pick.