Page 57 - The Veterinary Care of the Horse

Step mouth

This is the name given to an abrupt variation in height of the adjacent teeth (Figure 2.12). It
VetBooks.ir arises owing to missing teeth in the opposite jaw or abnormalities of eruption. Regular and

appropriate rasping can correct the problem. Where a tooth is missing, the opposite tooth
must be reduced every 6–12 months.

Figure 2.12 Step mouth

Shear mouth

This is the name given to the condition where the grinding surfaces of the molars are

abnormally slanted between the cheek and the tongue. The angle of the grinding surface or
tables is normally 15 degrees to the horizontal. In a horse with shear mouth, the inside edge

of the lower cheek teeth and the outer edge of the upper cheek teeth grow abnormally long
and the grinding surfaces become steeper than normal (up to 45 degrees). This can be the
consequence of any condition which causes pain and prevents normal side-to-side chewing.

It also occurs in horses with abnormally narrow mandibles. The chewing action becomes
more of an up-and-down movement. High concentrate diets with little forage may contribute

to the development of this condition.