The head of a horse has been divided below the orbits, and a back view of the facial portion is here shown, the spectator being supposed to look into the cavities, which have been thereby exposed. a indicates the molar teeth on that side which was not the seat of disease, and they are of the natural length and obliquity. b denotes the teeth on that side where the disease was seated, and shows them to be not only unusually slanting on their grinding surfaces or tables, but also of considerable length. It was the last tooth on this side which was carious, and the shape of the molars has been occasioned by the animal during its life, being unable, because of pain, to freely use these organs in chewing its food. The effort to avoid any stress upon the diseased tooth, has caused those on the same side to suffer only partial attrition; hence they have become long and slanting, presenting sharp pointed edges, which lacerated the lining membrane of the mouth. The incisors, a distant view of which is given, likewise display the consequence of the animal’s mode of feeding. Turning from the teeth to the exposed cavities above them, it will be seen that these are not symmetrical, or of equal dimensions, which in the head of a healthy subject, they undoubtedly ought to be. Those on the diseased side are not only the largest, but differently formed. The alteration has resulted from the inflammation and accumulation of pus within them. Something besides pus, however, has been thrown out. e represents the healthy maxillary sinus as an empty space: d is the like part, but it is here filled by a fine cellular structure composed of bone, which has been produced by the action of disease. The plates which form the cells are delicately thin, and beautifully arranged: the little cavities were once full of a thick and sanguineous matter, and the larger spaces above them contained a very fetid but almost solid substance, which was pus, that, by being pent up, had become of a cheesy consistency. c indicates the nasal division, or cartilaginous wall, which separates the two chambers of the nose. As will be observed, it has been forced on one side by the enlargement of the affected parts.
60. The agents which are likely to injure the teeth, have been, perhaps, too little regarded, especially when the importance of these organs to the horse is considered. Some grooms, to increase the appetites of the animals under their care, sprinkle vitriol, or sulphuric acid upon the food; and the horse will ultimately become fond of this kind of seasoning to his corn. Some veterinary surgeons, even of high standing, will administer monstrous doses of the sulphates in solution; and others will mingle, for a lengthened period, large quantities of the acids in the animal’s water. No suspicion seems hitherto to have been entertained of the ill effects likely to ensue upon a mode of treatment, which is often prolonged for months. The human physician, however, has remarked, that most acids have a tendency to affect the teeth, and that sulphuric acid, whether in the diluted state, or in combination with substances of low affinity, is particularly destructive in this respect. The patient who now takes the soluble preparations of iron, is provided with an instrument to convey the liquid into the pharynx, and prevent any portion of it from coming in contact with the teeth. Those who swallow such a form of medicine, without employing the tube, soon exhibit the consequence in the general discolourization and decay of the mouth. The man, however, gulps his physic, and can rinse out his mouth if the taste be retained; the horse, when it takes a drench, holds the liquid for a considerable time before it swallows, and the administration of the fluid is not very quickly accomplished. Now, in proportion to the duration of contact would be the effect; and if the hasty deglutition of the one being cannot save the teeth from the ravage of the sulphate, is the prolonged retention of the substance likely to be without effect upon the same organs in the other? The horse, however, takes the sulphates of a strength which the human being would not survive—where the one for a dose swallows a grain, the other may imbibe a drachm. The consequences must bear some proportion to the quantity, nor will the composition of the horse’s tooth allow us to suppose that it is less affected by chemical agents. The enamel of the horse is more speedily acted upon than that of any other animal I am acquainted with; and the substance being unorganized, the results obtained by experiments tried on it when removed from the body, are as conclusive as any effects produced during the life of the animal. The sulphates are potent and valuable medicines; the Veterinary Pharmacopœia could not afford to discard them; but they can be administered in substance, and should with caution be exhibited in a liquid form. I am positive when promulgating this opinion, and nevertheless I have no instance of their injurious effects to adduce. I have not been able to trace caries in the horse to the use of the sulphates or of acids, but the mind often recognises what the senses fail to perceive; and the fact is so clear to reason, that it is not disproved, because it hitherto has not been rendered plain to the vision. Neither does it invalidate my conclusion to adduce instances where the horse had been observed to exhibit no affection subsequent to the use of these medicines. The negative can establish nothing. The cause has not been suspected, and the effect, of course, has not yet been observed; but we abuse our reason, if we refuse to listen to its teachings. I am not likely to have met with the proof it may be desirable I should adduce; for perceiving the evil I early forbore, to render possible any evidence of its tendency in my own practice. Herein lies my excuse; and though it may not be satisfactory to all, the arguments I have advanced, I think, must be plain to everybody. The sulphates, in substance, are as efficacious as when given in solution; and if so large doses cannot be administered in the former manner, the necessity for such prodigious quantities has never been demonstrated. Let it, therefore, only be admitted, that there is room for suspicion, and perseverance in the old practice is no longer justifiable. The number of horses that exhibit diseased teeth, teaches us to look for some cause. I cannot attribute every case to derangement of the digestive organs, or to idiosyncracy. The latter term rather avoids the question than elucidates it; and the former effect is as likely to be produced by imperfect mastication, consequent upon chemical injury to the teeth, as to be the primary cause of the disease of the masticatory organs.
61. The instruments used in connexion with the teeth of the horse are not very numerous. The gum lancet, shaped like that used by the human surgeon, and employed after the same manner, is seldom required, save for the tushes, when any knife will be found equally if not even more convenient. The rasp or file, for it is either, according to the taste of the surgeon, though most commonly the former, consists of the necessary part that gives the name to the instrument attached to a long lever, which is inserted into a handle. Its employment is rather laborious than difficult, and demands more endurance than skill on the part of the practitioner. Several of different degrees of coarseness should be used, and during the operation, a pail of water ought to be at hand, so that the roughened surface may be constantly washed and moistened, to increase its cutting power, and prevent it becoming clogged. The rasp, however, though fitted to reduce any slight inequality, or take down the sharp edges of the teeth, is not sufficiently operative to level the long projections that are often found in the horse’s mouth. For that purpose a guarded chisel has been employed; but the blow of the hammer or mallet very often fractures the alveolar cavities, and the cutting edge, despite the guard, generally wounds the mouth. The rasp may be tedious, but the chisel is dangerous; and neither one or the other are proper for the purpose, though till lately, these rude tools were the only dental instruments the veterinary surgeon could boast of. A want of some more surgical and appropriate means of shortening the projecting molars has long been seriously felt; and that want the ingenuity of Mr. T. W. Gowing, the esteemed practitioner of Camden Town, to whose inventive genius the members of the veterinary profession are so largely indebted, has at length supplied. The instruments he has constructed have two grand recommendations: they are equally simple and effective. Seeing how little complexity they exhibit, it seems strange that no one should have previously thought of them; but the same thing is generally said of every invention of real utility. The only difficulty in these matters is to catch the idea, and this Mr. Gowing has most happily accomplished. He has produced a complete set of veterinary dental instruments; discarding all of those which have hitherto been employed, with the exception of the mouth rasp, which he leaves untouched. Instead of the old tooth key which was so formidable to look at, but so difficult and often impossible to use, he employs a pair of forceps, of which the following wood-cut will give the reader some idea.
They are about twenty-two inches long, in order that they may be applied, if required, to the most backward of the grinders, and of such substance, as renders impossible any springy action which might cause the bite to be lost when the force was applied. As will be imagined, forceps of such dimensions are not to be used by the unassisted hand. The reader, by looking at the end of the handles, will observe that one is comparatively large: the smaller of the two contains within it a female screw, and the other is only a plain eye. To act on these, a cross handle or lever is added, and of this the following is an outline.
This, as is shown in the wood-cut, consists of two pieces, the smaller of which works freely in a hole made for its reception, and being curved at one end, can be either extended in the manner represented above, or laid close to the lever in the way depicted in the next view of the instrument. It is what is technically called a “tommy,” and its use is to gain dispatch and power in the employment of the forceps. The main part consists of a rod of steel, having in the centre a screw, which at the end towards the “tommy” exhibits an enlargement or shoulder. Such are the various parts, and when using them, the operator having fixed the claws of the forceps upon the tooth he wishes to extract, gives the forceps to an assistant, whom he orders to hold them firmly in their situation. He then takes the handle, and introducing it through the open eye with the “tommy” as rapidly as possible, winds it round until he feels the grasp is secure. Any amount of power can be thus obtained; for as the screw threads through one handle, the shoulder presses against the other, and thus forcing the claws together, fixes them upon the substance which may be placed between them. When this is done, the operator closes or folds up the free lever, and using both hands, has at his command a power which will not necessitate employment of his utmost strength.
The above wood-cut depicts the forceps as they appear when put together; and to render their mode of action more clear, a body indicative of the situation which the tooth would occupy, has been introduced. The advantages which these forceps have over the tooth-key in common use, are so obvious, that the reader will not require they should be pointed out. The benefits which this instrument confers, are indeed great; neither can it be supposed that the principle can be changed, or its adaptation improved upon. For its purpose, the thing appears perfect; and I can speak confidently as to the admirable manner in which it acts. One caution, however, may not be unnecessary. All surgical instruments are capable of being abused, and in exact proportion to their utility is their liability to abuse. With Mr. Gowing’s forceps a horse’s jaw could be easily broken, or he who did not know the power of the screw, would, if he kept on winding the handle, crush the tooth it was his intention to secure. So much strength is gained that the judgment must be employed to regulate it. Huge as the instrument looks, it requires delicacy in the hand which uses it. With such a tool at his command, a child is in power equal to a giant; and the man therefore must exercise his mind rather than strain his muscles, when he has to operate with it. In cautious hands it gives every facility that could be desired, and is both more certain in its action, and more expeditious in its results than anything of the kind which we at present possess, besides having the further advantage of not requiring those adjustments and unsatisfactory changes which the common instruments necessitate to be made. For extraction, nothing beyond these forceps is wanted: they answer every purpose; but the veterinary surgeon is less frequently called upon to extract, than to shorten the horse’s teeth. To this subject Mr. Gowing has likewise given his attention, and it is pleasant to state he has equally succeeded. The ordinary chisel was alike inefficient and dangerous. The guard was not sufficient to prevent the edge from seriously wounding the mouth, and the chisel could remove but a small portion at a time. The shock, moreover, was sustained by the tooth itself, which, transferring the force to the alveolar cavity, was too often the cause of fracture. When cautiously conducted, the operation was tedious, and the struggles of the horse were not devoid of danger. We were possessed of nothing which, at a single blow, could remove the entire bulk of a projecting tooth. To supply this desideratum was Mr. Gowing’s object, and the annexed wood-cut will, at a glance, convince the reader that the requirement has been satisfactorily complied with.