By cracked heel is understood a crack or breach in the skin of the heel. It is to all intents and purposes a wound, but owing to its peculiar position it requires to be specially considered. Wounds of the skin are not as a rule difficult to deal with; but when they occur in parts of the body where movement is constantly going on, the healing process is always more or less delayed, and sometimes rendered difficult to effect.
Cracks in the heel almost invariably run crossways, sometimes extending from one side of the heel to the other, at others being much shorter, when they are situated to the inner or the outer side of the heel just below the fetlocks; or a crack may occur in both positions, or it may be placed lower down in or towards the hollow of the heel.
Hind-legs and fore-legs alike are subject to this affection, but it is more common in the former than the latter. This difference is probably due -to the facts: (l) that the hind-legs are farther from the centre of circulation than the fore ones, and therefore more liable to aggravated attacks of congestion and inflammation of the heels; (2) that in badly-regulated stables they are more exposed to moisture and filth, conditions which contribute so much to the production of the disease.
In large numbers of cases predisposing influences play an important part in the cause of cracked heels. In this connection it is noticed that horses of lymphatic temperament, whose limbs are prone to swell from slight disturbing causes, are specially liable to the disease.
Animals in whom the circulation is enfeebled by age or poverty, and others of a plethoric habit of body, are equally susceptible.
The exciting causes of cracked heels are such as produce inflammation of the skin, hence it follows upon injuries done by ropes in casting either for operations, or by accident in the stables, and as the result of an extension of inflammation from the foot in certain forms of disease and accident.
The most common exciting cause, however, is the repeated exposure of the heels to wet and snow during the prevalence of biting easterly winds. Snow when mixed with salt and dirt, as sometimes encountered on the streets of our large towns, is a common inducing cause of inflammation and cracking of the skin of the heels. The disease is also produced by washing the legs in cold weather and leaving them exposed to dry.
The action of cold and wet in the induction of cracked heels may be stated as follows: - Cold, whether it is produced by cold air or the rapid evaporation of water, causes the blood-vessels of the skin to contract, and the quantity of blood circulating in the part is consequently reduced. If the application be continued for a lengthened period, or made repeatedly at short intervals, as when a horse's legs are allowed to become wet again and again and to dry under the influence of cold winds, the contracting power of the vessels is gradually reduced, and sooner or later becomes for the time being exhausted. As a result of this, the pressure of the blood within the vessels begins to assert itself and to overcome their resistance.
A reaction now sets in, and the vessels wliich have been caused to contract under the influence of cold open out and become widely dilated and at the same time morbidly distended with blood. This state of things continuing, results in inflammation, when the skin, before cool, now becomes red, swollen, hot, and tender. At the same time moisture oozes through the surface, and the tissues having lost their cohesion, split across in consequence of the frequent bending of the joint.
Cracked heels are invariably attended with more or less lameness. In progression, and especially at starting, the legs are raised some distance from the ground, and are sometimes sharply caught up and suspended in the air. The limb about the fetlock-joint, and maybe as high as the knee or hock, is swollen and more or less painful to the touch. A discharge of a sticky and sometimes of an offensive character flows from the wound, and the horse stands with the fetlock-joint* in a semi-flexed condition.
The objects of treatment will be to subdue existing inflammation and bring about healing of the wound. The first of these indications will be best accomplished by the prompt administration of a dose of physic; at the same time the diet should be carefully regulated, and consist for the most part of bran and a little crushed corn. After the physic has ceased to operate, a little green food, carrots, or other roots should be supplied morning and evening.
In the matter of local treatment, a poultice of linseed-meal or boiled carrots should be placed on the heel and secured by a long flannel bandage wound round the leg as high as the knee. The bandage should- be so adjusted that the pastern cannot be flexed, or the lips of the wound will be repeatedly drawn apart during movement, and healing thereby delayed.
The poultice should be changed not less than three times daily, as when allowed to get foul it tends to irritate rather than soothe.
When the inflammation has subsided, the wound should be dressed two or three times a day with some antiseptic powder or solution, and covered by a pledget of cotton-wool and secured by a bandage as before. As soon as may be, the wool and bandage should be discontinued, and the part kept freely dusted over with a powder composed at first of boracic acid and flour or prepared chalk, to which a little alum may be added later. Where, as is sometimes the case, the edges of the wound become callous and refuse to heal, a little caustic must be freely applied to them, so as to excite a fresh granulating or healing surface.
When the wound has healed, and the skin resumes its normal condition, it should be carefully guarded against undue exposure to wet and dirt, as a return of the mischief may be easily provoked by these means.