130 DISEASES OF THE TEETH. 



Horses, kindly and not prematurely used, sometimes live to be- 

 tween thirty-five and forty years of age ; and Mr. Percivall gives 

 an account of a barge horse that died in his sixty-second year.* 



DISEASES OF THE TEETH. 



Of the diseases of the teeth in the horse, we know little. Ca- 

 rious or hollow teeth are occasionally, but not often, seen ; but 

 the edges of the grinders, from the wearing off of the enamel, oi 



* Note by Mr. Spooner. — We have little to add. There are exceptions, 

 however, to the above rules. We have known a horse at twelve exhibit 

 the same appearance as another at six. In such instances, the age must be 

 judged by the length and shape of the teeth, and more particularly by the 

 shape of the faces of the teeth. 



A careful examination leads me to believe that the observation in the text, 

 that the teeth are developed much earlier in young animals that are corn- 

 fed and taken early into the stable, and that in thoroughbred horses, conse- 

 quently, the changes of the teeth are earlier than in animals that remain 

 more in a state of nature, is erroneous. I think them, of the two, rather 

 more backward. Many successful attempts have doubtless been made to 

 run four year old horses for three year olds, as in the celebrated-case of 

 Running Rein, which obtained such notoriety. An incisor tooth, when it is 

 first shed, and for some time afterwards, is higher on the outer or Tront 

 edge, than the inner or back edge. After some time, this outer edge is worr 

 down to the same level as the inner, and subsequently both edges wear 

 equally, till the bottom of the hole which forms the mark is reached, when, 

 of course, the mark disappears. It takes about three years to effect this 

 process, that is, from the time the tooth is cut to the disappearance of the 

 mark. In a four year old mouth, there are four permanent lower incisors, 

 and two corner temporary teeth. The outer and inner edge of the central 

 teeth are tolerably level, and the mark smaller than the middle teeth next 

 them, which present the appearance of younger teeth. Now, in a three-year 

 old mouth the central teeth have a younger appearance, the mark being 

 larger, and the outer edge higher, than the inner, whilst the middle teeth 

 are either in the act of being cut, or the temporary teeth have not yet dis- 

 appeared. By careful examination, therefore, the difference between a three 

 and four year old horse can be readily detected. The permanent teeth 

 differ from the temporary, being larger, less while, and having more depth 

 above the gums. 



After the marks have disappeared, the age of the horse may be judged 

 partly by the shape of the faces of tlie teeth, and partly by the horizontal 

 position in which the teeth proceed from the jaw. If we take a young in- 

 cisor tooth and saw it off below the bottom of the hole which forms the 

 mark, and again at a similar distance lower down, we shall find that the 

 several surfaces made by the sections resemble the shape of the face of the 

 tooth in a horse in which a similar quantity of the tooth has been naturally 

 worn down. The comparison also holds good with regard to the direction in 

 which the teeth proceed from the lower jaw, being in the young animal up- 

 right or curved, and in the old one nearly horizontal. Although the teeth 

 grow to supply the loss of that which wears away, yet the original shape 

 remains, so that the face of an incisor tooth at different periods is owing io 

 that particular part which, in ' 



