Treatment - Preventive. - Seeing that at any rate the majority of cases of coronitis result from injuries inflicted by the shoes, we may look at once to that particular for a means of prevention.
Take first the case of 'treads'. There is no doubt that they are most common in animals shod with heavy shoes and with high and sharp calkins. This suggests at once that a preventive is to be found in substituting a calkin that is low and square.
Where the injury is an overreach, and where, on account of the animal's pace and manner of gait it is in risk of being constantly inflicted, the shoeing should be seen to at once.
We have already pointed out that it is the inner border of the lower surface of the toe of the hind-shoe which, in the act of being drawn backwards, inflicts the injury. (See Fig. 110).
In this case prevention may be brought about either by shoeing with a shoe whose ground surface is wholly concave, or by bevelling off the sharp border (see Fig. 110, a, p. 236). When the tendency to overreach is not excessive, prevention may in many cases be effected by simply placing the shoe of the hind-foot a trifle further backwards than would ordinarily be correct, thus allowing the horn of the toe to project beyond the shoe. This at the same time does away with the annoyance of 'forging' or 'clacking,' which, as a rule, accompanies this condition.
While recognising the value of shoeing in these cases, we must not forget that a great deal may be brought about by careful horsemanship. The animal should be held together and kept well up to the bit, but should not be allowed to push forward at the top of his pace. With many animals of fast pace and free action overreach is more an indiscretion of youth than any defect in action or conformation, and his powers should therefore be husbanded by the driver until the animal has settled down into a convenient and steady manner of going.
Fig. 110. - Under Surface Of The Toe Of A Hind-Shoe. A, Marks The Portion Of The Inner Margin That Inflicts Overreach.
Fig. 111. - The Inner Margin Of The Inferior Surface Of The Hind-Shoe Bevelled To Prevent Overreach.
Curative. - Although in some cases it is so small as to go undetected, we may take it that in all cases of coronitis there is a wound, with consequent danger of septic infection of the surrounding parts. Therefore, after attention to the shoeing and removal of the cause, the first indication in the treatment will be to render the parts aseptic. This is best done by removing the hair from the coronet and soaking the whole foot in a cold antiseptic solution. After removal from the bath, the coronet may be dressed with a moderately strong solution of carbolic acid or perchloride of mercury. When the injury is slight and recent, such is sufficient to effect resolution.
When marked swelling persists, however, and the increase in heat and tenderness denotes the formation of pus, recovery is not so easily obtained. In this case the application of hot poultices or hot baths is called for. By these means suppuration is promoted and induced to early break through in the most favourable position - namely, the softened skin of the coronet. The pus so escaping is always more or less blood-stained, and contains both large and small pieces of broken down and decomposed tissue. After discharge of the pus, the cavity remaining should be mopped out with an antiseptic solution, and a pledget of antiseptic tow or other material left in position. All that is then needed is constant dressing in a suitable manner. We prefer in this instance washing some three or four times a day with hot water until a perfectly clean wound is obtained, and, after the washing, painting the raw surface with a strong solution (1 in 200, or 1 in 100) of perchloride of mercury.
When the abscess we have described as forming is extremely large, or where it is more than ordinarily slow in 'pointing,' the likelihood of its having burrowed for some distance below the upper margin of the wall must be suspected. Here it is sometimes wise to thin the wall with the rasp immediately below the point of greatest swelling of the coronet. This will serve to lessen pressure on the sensitive structures beneath.
Immediately the abscess contents have found exit at the coronet, the cavity formerly occupied by the pus should be explored. If to any extent it is found then to have 'pocketed' beneath the upper border of the wall, a counter-opening should be made where the horn of the wall has been thinned with the rasp.
When it so happens, either from extensive bruising or from the action of excessive cold, that we have or suspect the condition of sloughing, then the first indication is to aid the live tissues to throw off the necrosed portion. In spite of what is sometimes urged to the contrary, a hot poultice is, perhaps, the best means of bringing this about. Directly the necrosed piece is shed, a wound remains which, so far as treatment is concerned, may be regarded exactly as that left by the formation of pus. Hot water applications, some three or four times daily, will serve both to cleanse the wound and also to maintain vitality in the tissues immediately surrounding it. After each washing, the use of a strong antiseptic solution to the wound is again beneficial.
In the case of an actual wound, whether, as in overreach, affecting the coronet alone or involving destruction of part of the wall, or, as in the case of toe-tread, penetrating the pedal articulation, the treatment to be followed is simple enough, in theory, if not always easy to carry out. It consists solely in maintaining a rigid asepsis of the parts until healing is well advanced or complete. The whole foot, including the coronet, should first be thoroughly washed in warm water. At the same time there should be used some agent that will tend to remove the natural grease of the parts. In this manner cleansing will be rendered more thorough, and penetration of the antiseptic solution to be afterwards applied made the more certain. The most ready way of effecting this is to use the ordinary stable 'water'-brush, and plenty of a freely-lathering soap.
This done, the foot should be rinsed in cold water, and afterwards constantly soaked in a cold antiseptic bath. Where it is inconvenient or impossible to have the constant bathing carried out, a dry antiseptic dressing may be tried in its stead. In this case the foot should first be thoroughly washed and dressed as before. Afterwards an antiseptic powder in the shape of a mixture of iodoform 1 part, boracic acid 10 parts, should be freely dusted on the wound, a pledget of carbolized tow or cotton-wool placed over it, and the whole maintained in position with a bandage previously soaked in a 1 in 500 solution of perchloride of mercury. Once on, this dressing should be allowed to remain until healing is complete. Should the animal manifest pain, however, by constantly pawing, or should swelling and heat of the parts be suspected, the bandage should be removed, and the condition of the wound ascertained.
An excellent example of the value of this method of treatment is that given below:
'I call to mind a valuable hunter in my practice a few seasons since, who, whilst hunting, we suppose, struck himself in the way we suggest. He not only removed the superior portion of the inner heel, but tore about 3 inches of the hoof from the top nearly to the bottom. This was clapped back by the owner, tied with a handkerchief, and the horse removed home. When the handkerchief was removed, I confess I did not think the horse looked at all like hunting again. The heel was fairly pulled down, the portion of the hoof that was hanging to it I could easily have wrenched off. The parts were fomented, however, with warm water which was slightly carbolized. I then removed a great portion of the heel and the lateral cartilage, which was split; placed the portion of hoof again on the laminae, smothered the wound with iodoform pulv., covered it with cotton-wool packing, and all the boracic acid I could get it to hold. A piece of linen bandage was then tightly wrapped a few times round, and the lot enclosed in a plaster-of-Paris bandage. I did not undo it for a fortnight, when, to my great pleasure, the heel and hoof presented a highly satisfactory appearance. I did it up in much the same way for another ten days, then put the sand-crack clamps into the hoof and fixed it to the sound part. The hoof remained in position while the new horn grew from the top, and the horse hunted again the same season.'[A]
[Footnote A: Veterinary Record, vol. ix., p. 501 (Bower).]