638 THE EXTERIOR OF THE HORSE. 



gum is touched. Soon after, the anterior border of the replacing 

 tooth, which has compressed, thinned, worn out, so to speak, the gum 

 from its deep to its superficial face, gradually appears and perforates 

 the latter by commencing at its internal moiety. This border is not 

 always directed transversely to the median line; it is sometimes 

 oblique from before to behind and from within to without. Little by 

 little the tooth disengages itself from the alveolus, arrives on a level 

 with its neighbors, and, finally, opposes itself to that of the other jaw. 



2d. The Milk-Teeth still in Place. The phenomena in this case are 

 less visible. It is not sufficient to make an examination of the incisive 

 arcades by their anterior faces ; it is also necessary to separate the two 

 jaws to see if there is any particular evidence showing that the erup- 

 tion of the permanent teeth is about to take place. It happens, even, 

 in certain cases, that this has already been accomplished for the pincers, 

 as we have observed in the English horse Vade-Mecum. After sepa- 

 rating the lips of the horse, only the milk-teeth were perceived, but on 

 opening the mouth, the superior permanent pincers, well developed, 

 and even slightly used, were discovered, while the inferior still remained 

 covered by the gums. 



We will remark, in conclusion, that nearly always the eruption 

 of the superior incisors is earlier than that of the inferior. In both 

 jaws it takes place by pairs, commencing with the pincers and termi- 

 nating with the corners. 



Causes which may hasten or retard the Eruption of the 

 Incisors of the Second Dentition. We cannot take under con- 

 sideration here the extraction of the deciduous teeth, a fraudulent 

 practice which we will, however, study separately ; but will speak only 

 of the physiological causes which may hasten or retard the eruption of 

 the permanent teeth. 



According to Girard, 1 the precocity of the race, the vigor of the 

 temperament, and abundant assimilation are capable of hastening the 

 eruption of the incisors of the second dentition, and of advancing it 

 three or four months. 



According to Traeger, 2 pregnancy can retard this eruption for a 

 year, notably that of the corners : 



All the pregnant mares, born in 1841, were no more advanced in 

 relation to the dentition than the unimpregnated ones which were 

 foaled in 1842 ; while other mares, also born in 1841, but which were 



1 Girard, loc. cit., p. 58. 



2 Traeger, Magazin fur die gesammte Thierheilkunde, 1846, in Recueil de medecine veteri- 

 naire, 1849, p. 136. 



