In this particular,

the horse differs entirely from animals in
general: for, generally speaking, as animals grow older their teeth
get blacker, but the horse's teeth grow whiter with age.

The so-called 'canines' come in between the sharp teeth and the
broad or blunt ones, partaking of the form of both kinds; for they are
broad at the base and sharp at the tip.

Males have more teeth than females in the case of men, sheep,
goats, and swine; in the case of other animals observations have not
yet been made: but the more teeth they have the more long-lived are
they, as a rule, while those are short-lived in proportion that have
teeth fewer in number and thinly set.