Many horses are kept in an unnatural environment–confined in stalls or small pens. Some of them resort to repetitive behaviors such as cribbing, weaving, or stall walking. Most of these horses are fed concentrated, high-energy rations they consume quickly, leaving them with lots of energy, but little to do. Horses raised on pasture, grazing continually on high-fiber, low-energy feed, are less likely to develop these habits.

Cribbing is an activity in which a horse grips a horizontal surface such as a rail, fence, or stall manger (in earlier years called a crib, thus the name of the problem) with the top incisors. The horse anchors his top teeth over the object or presses them into the wood, letting the lower jaw hang slack. He then flexes his neck, opens his throat, pulls back with his mouth open, and swallows air with a grunting sound.

The cribbing horse wears down his top incisors (the teeth often become so worn the top and bottom incisors do not meet when the mouth is closed), and he develops unsightly large muscles under the neck. This can interfere with proper head flexion when ridden.

Serious cribbers can lose weight; they become so addicted to their habit they prefer to crib than eat. Destruction of facilities is a frustration to horse owners. Once the habit starts, many horses keep cribbing–even if given access to pasture and grass. They kill trees, damage fences, and destroy stall dividers and feed boxes