GENERAL DISCUSSION.--The teeth are the passive organs of digestion. They
are hard organs, implanted in the superior and inferior jaws in the form of
a long and narrow arch that is open posteriorly. The free portions of the
teeth project into the mouth, and present sharp or roughened table surfaces
for the crushing and tearing of food. In solipeds and ruminants the arch is
interrupted on each side by the inter-dental space or bars (Fig. 51). The
teeth that form the middle and anterior portion of the arch are termed
incisors (Fig. 52). Posterior to the incisors are the canines or tusks, and
forming the arms of the arch are the molar teeth. Animals have two sets of
teeth, temporary and permanent. The following table gives the number of the
different kinds of temporary and permanent teeth.

Temporary Teeth Permanent Teeth
Incisors Canines Molars Incisors Canines Molars

Solipeds 12 12 12 4 24
Ox 8 12 8 0 24
Sheep 8 12 8 0 24
Hog 12 12 12 4 24

The tusks or canine teeth are not always present in the female. Ruminants
do not have upper incisor teeth. The temporary teeth are erupted either
before or within a few days to a few months after birth. The eruption of
the permanent teeth and the replacement of the temporary teeth occur at
different periods up to the age of four and one-half years (Fig. 53). It is
well to keep the following table of dentition in mind when examining the
mouths of animals for the purpose of determining their age.[1]

Horses Cattle Hogs