Page 390 - Anatomy and Physiology of Farm Animals, 8th Edition

Anatomy of the Digestive System / 375

against which the lower incisors abut Unlike the other equine cheek teeth, the
first upper premolar is very small, brachy­
when the jaws are closed. Permanent
VetBooks.ir incisors are preceded by a like number of dont, and does not come into wear. This
tooth is called the wolf tooth, and some
deciduous teeth.
Canine teeth (abbreviated C) are also horse owners prefer to have it removed
called eyeteeth, bridle teeth, tusks, and because of the perception that it may make
tushes. Ruminants lack canine teeth, and unwanted contact with the bit (Fig. 20‐4).
although they can be well developed in In the young horse, only a small part
stallions, they are typically small or absent of each cheek tooth is visible, as most of
in mares and geldings. The canine teeth of the crown lies developed but unerupted
pigs are large, especially in boars, and in beneath the gum (Fig. 20‐5). Throughout
this species they are usually called tusks. the horse’s life, these teeth continue to
Porcine tusks are described as open rooted, erupt, maintaining their intraoral
meaning that they continue to grow height even as they are worn down by
throughout life. The lower tusk is generally the coarse forage the horse eats. Equine
much larger than its partner in the upper cheek teeth are not open rooted; no new
arcade. In pigs, the permanent canines are dental tissues are created after the tooth
preceded by analogous deciduous teeth; in is initially formed. They are instead
the horse, the deciduous canines are often described as slowly erupting. Because
absent or so small that their crowns do of this phenomenon, horses are prone
not erupt. to develop sharp, elongated ridges of
Cheek teeth comprise premolars (P) enamel on their cheek teeth. These are
and molars (M), which in herbivores are variously called points and hooks, and
morphologically similar. Only premolars they may cause the horse considerable
are preceded by deciduous teeth; the pain if they cut the soft cheeks, tongue,
molars have no precursors. In the pig, the and gums. For this reason, it is consid-
molars are larger than the premolars and ered good husbandry to check for and
have a flatter occlusal surface. file down the points and hooks periodi-
The first premolar of horses is often cally, a procedure called floating the
absent, and when present, it is almost always teeth that is done with a special rasp
seen only in the upper (maxillary) arcade. called a float.

Figure 20-4. The first premolar or “wolf tooth” of the horse.