The Horse's Mouth, Showing the age by the teeth

by Edward Mayhew

SEVEN YEARS OFF.
The Corner Teeth without showing age,
exhibit further evidence of wear.

EIGHT YEARS OFF.
The Gum of the lower Corner Teeth has
become Square, and the lower Tush blunt.

51. At eight years off, the gum of the lower corner tooth has become square, and the lower tush blunt. The original drawing was made from the teeth of that noted horse, Oakley; and in order to render it as perfect as possible, the mouths of mares (Meal, Edgworth, Bess, &c.) have been compared. The departure from the circular form of the gum, as depicted in the coloured engraving, is even more marked than it was at the seventh year. Added to this change of figure, the gums appear more hard and less delicate; the mouth looks more firm, and seems to have attained the perfection of its strength. The margin of the lower jaw is now comparatively sharp, and the cheeks are flat. The crusta petrosa on the upper teeth is in a great degree removed; the enamel not yet, however, having a marked yellow tinge. On the lower corner incisors the crusta petrosa may still continue, but it no longer has a dull brown aspect: it is never prominent at this age, but rather speckled over the outer surface, than regularly enveloping any portion of it. It has a somewhat rough and worm-eaten aspect, and in colour is nearer to a dirty yellow than a dull brown. If the posterior angle of the upper corner incisor is pendant, or exhibits that species of notch, which was alluded to in the previous paragraph, it is at the eighth year well shown, and the table has undergone considerable alteration. There is now on the shell tooth, a full table, the infundibulum of which, if not obliterated, is always of lessened size, well marked out, and on all sides surrounded by a broad and a flattened surface. The other teeth have also changed their figures. The tables of the centre nippers have taken on a decided angular shape, and those of the lateral display no dubious tendency to assume that form. The infundibula may be obliterated, but more generally those in the lateral and corner teeth are retained, or if now absent, the circle of enamel will, on inspection, show that the cavity is only filled up by crusta petrosa, not absolutely worn out. The following wood-cuts exhibit the changes which the tables undergo; and as the eighth year is an important one, inasmuch as the horse which has attained it is called “aged,” a double set is here introduced, to show the difference of figure which these parts may present. In those tables, it will be seen the infundibulum has gone from a central nipper only; but even in that instance, a white mark indicates that the cavity is merely filled up by crusta petrosa, the enamelled lining not being yet worn out. The alteration in the form and magnitude of the infundibula cannot, if the accompanying wood-cut be compared with those which have preceded it, fail to strike the reader; indeed these changes, aided by the worn appearance of tables of the shell teeth, are now the principal guides when judging of the age by the mouth.

52. After the eighth year, there is no certainty in any opinion drawn from the teeth. A guess may be hazarded, and very often that guess will prove correct, but at the same time it should be received only as a conjecture. The chance of naming the age decreases as the number of years increase. After the twelfth, the probability of hitting the exact year is very small. After the sixteenth year, all is confusion, and there remains no sign which could warrant any person in pretending he could pronounce the age by the teeth. It is true that certain tokens may induce a conviction that an animal is much older than sixteen, and this conviction may be so justified as to amount almost to a certainty; but no man, I imagine, could form any opinion with regard to the number of years by which a horse exceeded sixteen, or pronounce a decision that should have any appearance of exactitude. They who pretend to an ability of this kind, may, in a few solitary instances, strike the point; but repeated failures will show that there is no positive principle in operation to guide the judgment. Indeed the age is most correctly told during the periods of dentition, and up to the sixth year. After the sixth year, the certainty is not so great, but a very fair, if not a positive judgment can be pronounced until the eighth year is accomplished. After the eighth year, no man should give an unqualified opinion concerning the age of a horse. After the twelfth, whatever may be pronounced should be offered only as a conjecture; and, after the sixteenth, the practitioner had better be silent. When stating this the author must be understood as expressing the conviction at which almost exclusive attention to the subject, and much necessary consideration, has enabled him to arrive. It must not, however, be thought that he is arrogating a power of measuring the capabilities of genius; his wish is only to declare the truth as he perceives it. The intention to publish a work upon the teeth has not been concealed; opinions have been solicited and information sought; the author has many obligations to acknowledge; all to whom he has made application have been liberal in their communications; but from no one has he been able to obtain anything opposed to the conclusions he has here promulgated. It may be that hereafter the power of judging of the age shall be extended. Pessina and the Girards thought it could be done with exactitude up to an extreme point, and saw a principle in the latest changes which the teeth undergo. The general experience in this country, however, seems to have decided that, after the eighth year, there is no certainty. With that decision the author is reluctantly obliged to acquiesce, and even to add that certainty is not to be obtained after the sixth year. This limitation, coupled as it is with a confession of inability, may seem to be a backward movement; but truth cannot retrograde. By ascertaining how far our present knowledge leads us, a motive is given to genius by the opportunity created for its exercise. No pains have been spared to investigate the hypotheses which have been made known; they have been candidly put to the test, and on the proof of their inefficiency discarded. That the reader may judge for himself, the tables of teeth, and mouths of various ages are presented. The altered aspect of the tables at the ninth year is indicated in the following wood-cut, which exhibits these surfaces as gaining depth and narrowing from side to side. This appearance they generally assume, and at the same time the infundibula are either lost or much contracted.

The next wood-cut, which depicts the form of the tables at the tenth year, though true in its general character, will serve to show how far dependence may be placed in ordinary signs, since the infundibulum of the lateral nipper shows a well-marked cavity, while from the other teeth it seems to be upon the eve of disappearing. On inspection, however, it will be seen that in figures the tables approach more towards the square, which is the last form these surfaces assume.

53. At twelve years old, there may be tartar on the lower tush. The teeth are longer, narrower, and the enamel darker. The coloured engraving, which was, on the last occasion justified by a comparison with the mouth of that famous horse, Charles the Twelfth, will convey a general idea of the prevailing characteristics of this age. The teeth have lost the white and firm set aspect they bore at the eighth year. Often, at this period, they have, by wear, become irregular generally, as exhibited in the plate; the grooves, extending down the length of the upper incisors, contain the remnants of the crusta petrosa, which is almost black. The upper tush is usually much diminished, while the lower is long, especially in stallions kept for service. The teeth project more outward and begin to arrange themselves more in a line, no longer showing the crescentic order which they assumed at five years old. Also, by the twelfth year, the tongue, when the jaws are closed, protrudes from the open space between the incisors and molars. The degree in which these alterations have taken place, together with the protrusion of the incisors, is all that is present to guide the judgment; and practical experience is needed, to give him, who attempts to decide upon such weak evidence, any chance of success. As in cases of this description every thing that can help the judgment is eagerly seized upon, the general appearance of the animal is always to be considered; and that may warn the practitioner to modify his opinion. The lower jaw is sharp, the cheeks flat, and around the tushes there may be an accumulation of tartar. It is true the tables, consequent on the wear of the teeth, will have undergone some change, but that alteration is now so slightly marked as not to enforce itself upon the observation. It is easily overlooked, and by no means easily recognised. The annexed wood-cut will suggest the nature of the change. In it will be seen a further remove from the oval form of these parts in the young mouth. The surfaces have become square or angular, and the corners are only sufficiently rounded to indicate what once was the shape which they exhibited.