What equine researchers continue to learn about this perplexing and frustrating stereotypy in horses

Hup. Huupp. <Pause> Huuuppp. If you’re hearing noises in your barn that sound like they’re coming from a pig/toad hybrid, you’ve probably got a cribber. Cribbing horses bite onto a hard surface, such as wood, then pull back to suck in air across their oropharynx, creating that characteristic raspy, croaking noise.

Cribbing—also known as crib-biting—is a somewhat rhythmic, repetitive behavior that seems to have no purpose. Therefore, it fits the definition of stereotypy. And while cribbing might seem pointless, that doesn’t mean it causes no harm. Long-term, it’s associated with abnormal dental wear and possibly poor body condition, poor performance, and gastrointestinal disorders—as well as damage to barn structures.

Scientists have been talking about cribbing for the past 400 years, says Sebastian McBride, PhD, senior lecturer in biological science at Aberystwyth University, in England. And they’ve been homing in on domesticated equine life as its primary culprit since the 1800s—without fully understanding why domesticated life would cause the condition.

Since then, scientists have been getting to the root of equine cribbing as they explore brain anatomy, genetics, potential causes, health consequences, welfare, treatment, and more. With each decade they’re learning more about the whens, whys, and hows of this and other stereotypies in horses, humans, and other animals. Here’s what we’ve learned about cribbing since we published our last research update eight years ago.

1. Cribbing is a stress-coping mechanism, not a ‘vice.’

More than any other factor, it seems horses develop cribbing and other stereotypies when they experience intense and/or prolonged stress, says Jéssica Carvalho Seabra, PhD, of the Federal University of Paraná, in Curitiba, Brazil, and Colorado State University, in Fort Collins. In 2021 Seabra completed a systematic review of recent scientific studies on factors affecting the development of abnormal behaviors, involving 18,863 equids.

Her investigations revealed people don’t always realize it’s the stress of domestic life that’s provoking stereotypies. A luxurious barn can still be a place of solitary confinement for a roaming, herd-living animal. And weaning at six months—while traditional—is a highly stressful event for a species in which nursing naturally lasts much longer.

“This is a problem because people from the equine industry like traditions,” says Seabra. “They like to keep raising horses the same way their ancestors used to do. So you can go to a very fancy equestrian facility, and you think, ‘They’ve got all this nice stuff, but they don’t have the basics.’ ”

On the other side of the globe, Swiss researchers and sisters Elodie Briefer, PhD, and Sabrina Briefer Freymond, PhD, have been investigating cribbing for more than a decade. Among their discoveries about the condition, they’ve found cribbing horses have lower cortisol (stress hormone) levels than noncribbers when learning complex tasks, provided they’re allowed to crib during the training session. This confirms cribbing might be a stress-coping ­mechanism