TEETH.
No fact is more discreditable to humanity than the small attention it has wasted upon the beautiful lives entrusted to its charge. Mortal pride asserts these creatures are given man for his use. Yes. But is the full use obtained? Are not the lives sacrificed? The horse has been the partner of mankind from the earliest period. For centuries at least the animal has been watched throughout the day; yet, even at this time, equine disorders are only beginning to be understood. Does this fact denote that care which such a charge demanded?
Cutting the permanent teeth seems, in the horse, to be effected at some expense to the system; it was a favorite custom with the farriers of the last century to trace numerous affections to the teething of the animal. Further inquiries have proved our grandfathers knew positively nothing about those growths, concerning which they assumed so much. The late W. Percivall traced sickness in the horse to irritation, arising from cutting of the tushes; there, however, our knowledge ends. Veterinarians have not, as a rule, either leisure or the necessary power to observe those animals it is their province to treat; they generally are but passing visitors to the stables into which they are called. Those who have studs of horses nominally placed under their charge feel they are retained not to watch, but to physic the animals to which the groom directs their attention.
The tushes of the upper jaw may, however, be fully up, and yet not have appeared in the mouth; this fact is easily explained. The advent of the tushes provoked acute inflammation of the membrane covering the jaw. The horse was cured of the attendant constitutional symptoms, but the cause of the disorder was mistaken. The acute inflammation changed into chronic irritation. The membrane, which in the first instance should have been lanced, thickened and imprisoned the tush beneath it; an incision is even now the only remedy, and should instantly be made.
Neither tushes nor incisors are known to be exposed to other accidents; it is, however, different with the molar teeth. These teeth consist of three components; bone or ivory constitutes the chief bulk of the organ, and over that is spread a thin covering of inorganic enamel, the whole being invested with a fibrous coating of crusta petrosa. The enamel is the material on which the tooth depends for its cutting properties; the manner in which the edge is preserved deserves attention, for the brick-layer's trowel appears to have been suggested by it. A thin coat of hard but brittle enamel is held between the two other bulky and tough substances, just as a thin layer of steel is protected by coatings of yielding iron in the house-builder's instrument.
The highly organized crusta petrosa is often injured; to understand this, we must first comprehend the vast power which urges the jaw of the horse. The motion resides entirely in the lower portion of the skull, which is moved by strong, very strong muscles, going direct from their attachments to their insertions. No force is lost by the arrangement, and no less a motor power was required to comminute the hays and oats on which the horse subsists. The machinery seems to be admirably adapted to its purposes; and to be so strongly framed as to defy all chance of injury. Man, however, has a mighty talent for evil; it does not always suit the convenience of the groom to sift the pebbles from the grain; corn and stones are hastily cast into the manger, and the poor horse, having no hands to select with, must masticate all alike. The reader can imagine the wrench which will ensue, when a flint suddenly checks the movement of the molar teeth. The crusta petrosa is bruised upon the large fang of the tooth. Disease is established, and sad toothache has soon to be endured.
A HORSE WITH TOOTHACHE.
Then there are the effects of the powerful acids in much favor with most grooms and too many veterinary surgeons; moreover, there are the sulphates, which in every possible form enter into veterinary medicine; the nitrates, likewise, are much esteemed, and are given in enormous doses. All of these much affect the crystalline enamel of the molar tooth; a small hole is first formed; into this the food enters and there putrifies; caries and toothache are the result.