why do horses crib (sway side to side) when they are hungry?

The Deep Dive

When observing horses, it is crucial to distinguish between crib-biting and weaving, as they are separate behaviors often confused. Crib-biting involves the horse grasping a solid object with its incisor teeth, arching its neck, and sucking in air, producing a characteristic grunting sound. Weaving, conversely, is a rhythmic side-to-side swaying of the head, neck, and forequarters while standing in place. Both are classified as stereotypies, which are repetitive, invariant, and functionless behaviors often developed in response to suboptimal environments or chronic stress. The underlying causes for these behaviors are complex and multifactorial. Factors contributing to their development include restricted access to forage, which can lead to gastric ulcers due to prolonged periods without food buffering stomach acid. Confinement, social isolation, and insufficient exercise also play significant roles, as horses are naturally grazing animals evolved for constant movement and herd interaction. These environmental stressors can lead to physiological changes, including altered neurotransmitter levels, prompting the horse to seek an outlet for tension. Stereotypies like crib-biting and weaving are thought to release endorphins, providing a temporary sense of relief or pleasure, thus becoming self-reinforcing. While hunger or forage restriction can be a contributing factor, these behaviors are rarely solely about an immediate lack of food but rather a deeper manifestation of welfare issues.

Why It Matters

Understanding why horses exhibit behaviors like crib-biting and weaving is crucial for ensuring their welfare and optimizing management practices. These stereotypies are not merely bad habits but significant indicators of environmental or physiological distress, prompting owners to investigate and address root causes such as inadequate forage, lack of turnout, social deprivation, or even gastric ulcers. Early identification and intervention can prevent the behaviors from becoming deeply ingrained, which can be challenging to reverse. Addressing these issues improves the horse's quality of life, reduces the risk of associated health problems like dental wear from crib-biting or joint strain from weaving, and can save owners substantial veterinary costs. Ultimately, recognizing the complex etiology behind these behaviors fosters a more empathetic and science-based approach to equine care.

Common Misconceptions

A major misconception is that "cribbing" is synonymous with a horse swaying side-to-side when hungry. In reality, crib-biting is an oral stereotypy where a horse grips an object and sucks air, while weaving is the side-to-side swaying motion. While lack of forage can contribute to both, especially due to digestive discomfort like ulcers, neither behavior is simply an immediate hunger response. Another myth is that horses learn crib-biting or weaving by observing other horses, making it "contagious." While social facilitation can occur, a horse's predisposition to develop these behaviors is primarily linked to individual genetics, temperament, and their specific environmental stressors, not merely imitation. Removing a cribber from a stable will not prevent other horses from developing the behavior if their welfare needs are not met.

Fun Facts

• Horses are hindgut fermenters, meaning they digest fiber in their large intestine, and their digestive system is designed for almost continuous grazing.
• Some studies suggest a genetic predisposition for stereotypies like crib-biting, with certain breeds showing higher incidences than others.