The feet, notwithstanding their dense horny covering, are by no means proof against pricks and other penetrating wounds. In the operation of shoeing, a misdirected nail is often accountable for the former, and the sole of the foot is frequently injured by forcible contact with sharp substances such as glass, wire, nails, and other sharp pieces of metal, stick, etc.
Pricks in shoeing, although mostly referred to want of care on the part of the shoeing-smith, are by no means so frequently due to this cause as is generally alleged. Horses with shelly, weak feet, or feet whose crust is much broken away, sometimes render the safe lodgment of a nail an almost impossible task, and, however careful a man may be, such feet can only be shod at great risk. It is, however, true that badly-driven nails, the careless stamping of nail-holes, defective pointing of nails, and badly-fitted shoes are not infrequently responsible for injuries to the feet by pricking and binding. It is, however, to be borne in mind that some horses are of such a vicious and uncontrollable character as to render such accidents possible in the hands of the most careful workman. Apart from shoeing, horses doing town work frequently pick up nails on the road, in the forge, or in yards or sheds where packing is going on, or in other places where nails, fragments of metal or glass are always to be found.
The frog, its commissures and cleft, being the softer parts of the sole, offer the least resistance to penetrating substances, and for this reason it is here that injury most frequently occurs. The danger attaching to pricks to the foot is not confined to the puncture alone, but is materially added to by any septic matter which may at the time be conveyed to the "quick " or vascular structures within.
The injury may be comparatively harmless, or serious, or even fatal, in its effects, according to the depth of penetration and the nature of the structures concerned in it. This will vary from a mere puncture of the sensitive sole or frog to a more extensive and penetrating wound involving the pedal-bone, the perforans tendon, the navicular joint, or the navicular bone itself.
The immediate effects of a prick to the foot are not always such as to attract attention at once, and it sometimes occurs that several days elapse before its existence is suspected; but as time goes on, and the injured part inflames and suppurates, pain and lameness are developed, and a search after the cause is provoked.
It is good practice, in all cases of lameness where the cause is obscure, to remove the shoe and thoroughly explore the foot, and especially so where the lameness is sudden in its onset or the animal has been recently shod.
Not infrequently this task is omitted because the fetlock is enlarged, hot, and tender, and the conclusion is too hastily arrived at that the joint has been subjected to sprain. After days of acute suffering, the error is made known by the appearance of an abscess at the coronet, when it becomes clear that the swollen joint was the result of extension of inflammation from the injured foot.
In searching the foot every nail and nail-hole should be closely examined as the shoe is removed, and any moisture upon the one or oozing from the other must be taken to indicate mischief. A thin layer of horn should then be removed from the sole and frog, and the foot pinched round its outer edge, the operator noting at the time any flinching which may be evinced at any particular point. Where a prick is found to exist, all horn must be taken away from around it until the bottom is reached and the sensitive structures laid bare. If it is found that a piece of nail, or glass, or wire has been broken off and become embedded in the tissues, it can then be removed. Any neglect or oversight in this connection is likely to be followed by most serious results.
The wound must now be treated antiseptically. In the first place the foot should be immersed in a pail of warm carbolized water or a 3-per-cent creolin solution and thoroughly cleansed, after which the wound should be irrigated with a solution of bichloride of mercury of the strength of 2 parts in 1000. A thick pad of cotton-wool or some other suitable well-baked dressing should then be applied to the part and secured by a bandage or strips of wood stretching across from one side of the foot to the other, and fixed between the shoe and the crust. The foot may now be enclosed in a clean leather boot.
When overlooked or neglected these penetrating wounds give rise to serious complications, of which abscess in the foot is the most frequent development. As a result the horn becomes separated from the sensitive parts beneath, giving rise to that condition known as "quittor", which is treated of elsewhere. Necrosis or sloughing of injured bone may also be among the results. Joints may be laid open, tendons and their sheaths inflamed, and the leg may swell as the result of inflammation extending along the cellular tissue (cellulitis) from the foot upwards.
In all these conditions the lameness is severe, and in some no weight can be borne on the foot. The animal stands with the toe lightly resting on the ground, lifting up the leg now and again and holding it suspended in the air as the result of pain.
The slighter injuries, when promptly attended to, readily yield to treatment and a few days' rest.
In all cases of pricks to the foot in which swelling of the coronet or persistent lameness remains after subsidence of the acute symptoms, a repetition of blisters over the pastern during a rest at grass will prove beneficial.