This may be defined as a sinuous wound on the wither, or that part between the neck and back at the top of the shoulder-blade.
These are similar to those of poll evil, viz. injuries, and are usually inflicted by the collar or saddle bruising the skin and tissues beneath, on the top, or at the side of the withers. It may be caused by the structures being pinched between the collar and a badly-fitting saddle.
A very common cause is the chafing produced by the edge of the rug, especially when it is fixed by a buckle or strap at the breast and the rug shifts back until its edge is drawn tight over the withers and chafes the skin at this part; or it may result from injury inflicted while rolling, or being cast in the stable, or from a bite from another horse.
The symptoms at first are usually a small swelling, which is rather sore and tense, on the top of the withers, or it may be to one side. If this is neglected and the cause not removed, the skin will very soon be broken, and then matter (pus) is formed and oozes from it. When only the skin and the tissue immediately under it are affected, little trouble need be anticipated, but if the cause is not removed the deeper structures (muscle and fascia) and even the bones (vertebral spines) may become diseased. Horses that have very high withers, and those poor in flesh, are most liable to be chafed by ill-fitting harness. Animals also of the heavier class are more often affected, probably because the harness of such animals is not so carefully fitted, nor kept in such good condition, the loads are heavier, and the work much rougher than with those of the lighter breeds.
Fig. 425. - Fistulous Withers.
Frequently the bruise is so severe that matter forms (abscess), which after a time burrows amongst the muscles, and finally breaks out through the skin on one side of the wither. The matter is assisted in finding its way between the muscles by the movement of the parts during progression. In this way pipes (sinuses) are formed in various directions leading to the open wound at the surface.
The treatment consists in the first place of removing the irritant, whatever it may be, and keeping the animal as quiet as possible, to prevent the muscles moving on each other. If the skin is not broken, and the swelling appears tense, hot, and painful, cold applications may be applied to try and reduce the inflammation and the swelling. These may be in the form of cold-water douches and cooling lotions applied by soaking linen cloths and placing them across the wither. If in the course of a few days the swelling does not disappear and the pain subside, but on the contrary continue to increase, we may expect that suppuration is taking place and that an abscess is about to form; that being so, the sooner we get the matter to the surface the better. To this end, hot water fomentations must be diligently applied, together with some stimulating liniment, such as that of ammonia and turpentine. When this does not succeed, a blister will often be beneficial. As soon as the swelling points, it should be lanced and well opened up to the lowest part of the cavity, so as to give free exit to the matter (pus) and allow of the removal of any dead tissues that may exist, and drainage of the abscess may be effected by passing a piece of tape (seton) through the wound, being careful to bring it out at a lower level than the floor of the cavity, so that no matter may be allowed to accumulate there.
Sometimes the pus will have burrowed behind the shoulder-blade, in which case a depending opening must be made or a seton passed through it. At other times the projections of the backbones (vertebral spines) will be diseased, in which case they must be freely scraped or removed by the veterinary surgeon.
Fistulous withers, like poll evil and quittor, are tedious cases at the best of times, especially if the deeper structures are involved, particularly the bones and fibrous tissue (fascia). In all cases where the diseased part can be found - which is not always an easy task - it is best to remove it with the knife. When this cannot be determined, the wound throughout should be well cauterized, with the hope of bringing away the injured and offending tissue. If this is not accomplished and the wound heals up on the outside, as it frequently will, a fresh abscess will form sooner or later, and the whole process will have to be gone through again; therefore it is useless to let the wound heal at the surface before the inside has grown up sound, or, in other words, the wound should be made to heal from the bottom. It is an old but sometimes successful practice to "plug" the sinus to the very bottom with some caustic, such as corrosive sublimate, or arsenic, or a mixture of the two. This destroys the tissues for some distance around, and frequently brings away the damaged structure that prevented healing in the first instance. When this happens the result is very satisfactory, because as soon as the dead part (slough) is removed, the wound at once begins to close, and only requires to be kept clean and have antiseptic lotions applied at frequent intervals to ensure a cure. When the wound has healed, two or three weeks should be allowed to pass over before the animal is again put to work, so that the injured part may become thoroughly restored.
Always have well-padded and properly-fitting harness and clothing, and as soon as any sign of chafing occurs, at once remove the offending agent. In this way many tedious and painful wounds may be avoided.