A bruised sole can be caused; when a horse stands on a stone or hard object, when the ground is very hard, (especially if the horse is unshod or has thin soles) or when the shoes are poorly fitted. Beneath the insensitive sole there are laminae which are densely supplied with blood vessels and nerves. Damage to the sole can cause disruption to blood vessels and swelling, which results in pressure between the sensitive laminae and the more rigid sole. This causes pain and lameness which can be compared to a bruise under the fingernail.
The affected horse usually becomes suddenly lame, often in one limb. The lameness can be severe and may appear to improve, only to reoccur several days later. A bruised sole is diagnosed by your veterinary surgeon or farrier by the careful application of hoof testers to establish solar pain. In addition, there is often a bounding digital pulse. At this point the sole is carefully pared and examined to check for the presence of a subsolar abscess, whose symptoms can mimic those of a bruise. Paring may reveal a visible red patch, the bruise. Often the vet or farrier will remove the shoe and apply a poultice and protective padding, which is replaced every 24 hours. Non-steroidal anti-inflammatory drugs are administered and the horse is box rested. Rapid progress is usually made within 48 hours. If lameness persists the foot should be re-examined and even radiographed, in case of an abscess or pedal bone fracture.
The risk of solar bruising can be reduced by; regular farriery, shoeing, care to pick out the feet before exercise, avoidance of exercise on stony or hard ground and the use of protective hoof pads for thin soled horses.