The full-grown dog has twenty teeth in the upper jaw, and twenty-two in the lower one. The central front teeth and the tushes pierce the gums before, or very shortly after, the birth, and the others protrude very rapidly. They remain only a very short period compared with the horse or with cattle, for by the time he is four or five months old the mastiff has all his permanent teeth complete, but the teething of the spaniel is not over until he is seven or eight months old.

The teeth preserve their freshness and whiteness until the dog is twenty months or two years old, when they begin to be tarnished, and the fteur-de-lis shape of the front teeth is changed to a more rounded one. This is hastened or retarded by the general health of the dog, and by the kind of food on which he lives, so that there is nothing about them that will indicate the age with any degree of certainty. The dog of five years old, who has plenty of exercise, and is fed on soft meat, will have a mouth full two years younger than another who has been in constant confinement, or who has been fed on bones; and the difficulty of judging of the precise age increases every year. In the general course of things the middle front teeth of the lower jaw begin to be rounded in large dogs at sixteen months, and in smaller dogs, at between twenty and two-and-twenty months, and the central lobe of the fleur-de-lis is gone, and the whole of the edge is level, at between three and four years old.

The same process commences in the next incisors between two years and a half and three years, and terminates between four and five; and in the corner front teeth it commences at four years, and is completed at five. The wearing away of the upper front teeth begins at a later period, and that has not been so carefully noted.

The tushes do not generally appear to be rounded until the front teeth are more or less changed, and they longer retain their freshness of appearance. The indications of age in them are vague and variable, and depend still more on the habits and food of the dog than do those of the other teeth.

The diseases of the teeth of petted dogs are often difficult and disgusting to treat. Before the inmate of the drawing-room becomes three years old, tartar begins to accumulate round the roots of many of the teeth. While it grows downward on the teeth, it also presses upward against the gums, and inflames and corrodes them, and the breath becomes offensive.

If the case is now neglected, the dog soon becomes a perfect nuisance to all about him. The tartar will be collected thickly about the teeth; it will eat deeply into the gums; it will form extensive and fcelid ulcers on the inside of the lips; many of the teeth will become loose, or drop out; and the breath of the animal is absolutely poisonous.

As a local application, healing the gums and sweetening the breath, equal parts of the tincture of myrrh and water will be most excellent. It should be daily applied until the cleanness of the teeth, and the healthiness of the gums, show that the evil is got rid of. A weak solution of the chlorides of lime and soda will also be found very useful for removing the present foetor; but they must not be continued longer than is necessary, for they are of a caustic nature, and corrode and destroy the enamel