Ah, the big "C". Cribbing. It's always a hot topic among equestrians, and for good reason. Cribbing, or crib-biting, is a stereotype that leads to almost certain and unsightly destruction of fencing and other objects around the stable - but more importantly, can have an effect on the horse's health. What's more, there's a pretty pervasive rumor going around the horse world that horses can learn to crib from other horses. It's hard to locate the origin, but seems one of those traditional horseman's tales that has stuck around over time. I've noticed from conversations that the issue seems to lead to tensions between barn owners and boarders who own cribbers, and also between some people who own non-cribbers and are afraid their horses will learn to crib from the cribbers. (Say that ten times fast.) I recently noticed the topic crop back up in a popular Facebook group for horse folks, so I thought I'd dedicate a post to offering a more solid answer to the question: "Do horses learn to crib from other horses?".
The "Big C"
First, let's define cribbing. Sometimes confused with wind-sucking or wood-chewing, it is actually very distinct: the horse grasps an object (oftentimes a fence board) with its teeth and sucks inward rapidly, making a grunting noise. Known as a stereotypy, it's repetitive in nature, extremely difficult to stop, and has a few known possible causes. In Equine Behavior: A Guide for Veterinarians and Equine Scientists (Second Edition), author Paul McGreevy lists the potential causes as: trauma from an abrupt weaning process, the feeding of concentrates (grains) to foals directly after weaning, small amounts of daily forage, and stable designs that limit communication between neighboring horses. Genetic predisposition is another commonly noted risk factor. Of course, it's often impossible to know what caused cribbing in the first place for each individual horse. Most of us end up with cribbers way after they started cribbing, and by that time, the cause is less important than learning to deal with it.
Because ultimately, we do end up dealing with it. Broken boards are annoying, but the health issues to our horses (worn-down teeth, weight loss, stomach ulcers, colic, etc.) are of real concern. Though some horse owners say they've found success with cribbing collars, it seems to be the rare case that anyone has found a lasting "solution". The problem, of course, is that horses who crib become truly "hooked" on cribbing because they discover an instant chemical reward in the form of endorphins and dopamine. They want the feeling, so they keep doing it. And our addition of devices to try to stop the cribbing - cribbing collars, physical barriers to surfaces that the horse cribs on, etc. - has been found in studies to actually increase the stress level in horses, thereby increasing their urge to crib. I could really go on and on about all the studies that have been done on possible "cures" for cribbing - shots of blockers that inhibit the release of dopamine by endorphins*, changes in diet, and more. But that's not why we're here today.
"They want the feeling, so they keep doing it."
So, back to this rumor about horses learning to crib from other horses. We've already discussed all of the currently researched factors for cribbing above. And notably, watching another horse crib has not been listed as a factor by the current science, as of yet. But I want to take it a step further and talk about why it doesn't seem that horses can just pick up cribbing like human teenagers pick up smoking at parties.
When we talk about horses learning to do things from watching other horses, we're talking about something called social learning. Unfortunately, the vast majority of research studies done on social learning in horses have disproven the theory. Although most of these studies are done by asking control groups and demonstrator groups to fulfill some sort of task, like opening a box or navigating an obstacle in an arena, the same general science applies to cribbing, which you could argue is a more intricate task and even more difficult to figure out how to perform just by observing.
"But what about the stories of horses that started cribbing after they saw another horse crib?", you want to know. I've definitely heard those stories, too. Well, if the science largely disproves social learning, then we have to look at what other common factors could be causing the same stereotypy across different horses. Genetic predisposition is certainly a component. But let's not ignore possible management factors: if all horses are receiving too little forage, or if they are all in a stable environment where they can't see one another and have very little turnout to fulfill their social needs, then it's possible for multiple horses to begin cribbing. Not because of one another, but because they are all living within the same environment.
With all of this considered - the current knowledge of what risk factors lead to cribbing, and the research on social learning - there is only one clear conclusion:
Cribbing is a not a contagious behavior, and cannot be learned by horses who watch other horses crib.
*Regina A Rendon, Louis Shuster, Nicholas H Dodman,
The effect of the NMDA receptor blocker, dextromethorphan, on cribbing in horses,
Pharmacology Biochemistry and Behavior,
Volume 68, Issue 1, 2001, Pages 49-51, ISSN 0091-3057,