SMOOTH MOUTH.--In old age the tables of the molar teeth may become so
smooth that the horse cannot grind or masticate the feed. When all of the
molars are in this condition, a rubbing sound may be noted when the animal
is masticating hay. After attempting to chew the hay, it may be dropped
from the mouth. Innutrition always occurs.

_The treatment_ consists in feeding chops and soft feeds.

DENTAL DISEASES.--Inflammation of the alveolar periosteum is a common
dental disease in domestic animals. This is an inflammation of the alveolar
dental membrane that fixes the tooth in the tooth cavity.

Injuries to the gums and cracks or fissures in the tooth are the _common
causes_. Caries or tooth decay is not uncommon. The predisposing factor is
a poor quality of enamel and dentine. The process of decay is assisted by
microorganisms.

The _early symptoms_ may escape notice. Slobbering, masticating on one
side, holding the head to one side, retained masses of food in the mouth
and a disagreeable odor frequently occur. Caries may be indicated at first
by a dark spot on the table of the tooth, later by a cavity. In horses,
inflammation of the alveolar membrane results in a bony enlargement on the
side of the face if the superior molar is involved. A swelling of the jaw
and fistula may result if a lower molar is involved (Fig. 57).

[Illustration: FIG. 57.--Fistula of jaw. This condition was the result of
neglected treatment of decayed teeth.]

_The treatment_ consists in the prompt removal of the tooth. This is more
difficult in young animals than it is in the middle-aged or old. Unless the