The tusks, four in number, in both sets are strong, elongated organs, conical in form, and curved in an outward and backward direction. The upper fangs are the strongest, and there is a small space between them and the corner incisor teeth, in which the lower tusks are situated when the mouth is closed. Most of the molars terminate in sharp lobes, and, consequently, are well adapted for tearing and crushing. They are, as a rule, twenty-six in number, seven on each side of the lower jaw, and six on each side of the upper one; but sometimes there are seven on each side of the upper jaw, the same as the lower. It is not an uncommon occurrence for a dog with a short face, like bulldogs, spaniels, and pugs, to have only five upper molars, and six lower molars. But there are only twelve temporary molars—three on each side of both jaws.
A puppy, when born, has no teeth visible, though the milk ones are formed and in the gums, and in some cases, their outline may be seen through the mucous membrane.
The milk teeth are smaller, softer, and more pointed than the permanent ones, and they are not situated so closely together. The tusks, too, are slightly pink in colour just above the neck, which is not the case with the second ones.
Puppies of different breeds vary in the time when they cut their teeth, those of the larger kinds cutting them earlier than small dogs; and though a fox-terrier puppy’s teeth appear earlier than a toy terrier’s, yet St. Bernards have them still earlier.
The process of dentition of the milk teeth is usually carried on without any trouble at all to the puppy. Such is not the case with respect to the cutting of the permanent ones, for it is a very common occurrence for puppies at this time to have convulsions. In other cases, at this period, eczema is very often troublesome, which, in some instances, continues after dentition is completed.
With regard to the cutting of the deciduous teeth, the first that appear, in most cases, is the middle molar on each side of the lower jaw. These pierce the gums in puppies of large breeds like St. Bernards, about the eighteenth or nineteenth day after birth. Puppies, like greyhounds, retrievers, fox-terriers, and others of similar size, do not cut these same teeth until about four days later, whilst puppies of the toy class are often a week later still.
About a day after the second lower molars have appeared, the upper incisors show themselves; the nippers and intermediates are the first to make their appearance. These are followed the next day by the upper corner incisors, and about the same time the lower corner incisors pass through the gums, and the tusks are erupted; but it often happens that all the incisors pass through the gums together, and the tusks at the same time, or just a day or so later.
About the fourth week, the last or third lower molar, and also the first one, have been cut, and are fairly well up; and about two days later, the middle upper molar is just appearing. In a day or two more, the last upper molar is erupted; and a couple of days afterwards, the first upper molar, which is the last to be cut, now makes its appearance.
By this, it will be seen that large puppies, like St. Bernards, have a complete set of milk teeth by the fifth week. Puppies of the smaller breeds are, as previously stated, a few days later.
It may be here remarked, that bitch puppies invariably cut their teeth rather better, and somewhat earlier, than dogs. Winter puppies are a little later in getting their teeth than those born in the spring.