Why Do Horses Weave?

Why Do Horses Weave?

Horses that weave often do so while standing at the stall door. Increasing visual or physical contact with other horses and optimizing turnout time can help reduce weaving.

Photo: Anne M. Eberhardt/The Horse

Q. I’m curious about my horse’s weaving. I know that excess calories/energy can play a factor, as can stress or some other trigger (though I haven’t really been able to spot a consistent “trigger” for my horse’s episodes—it can range from being handled in his stall to standing and the apparent anticipation of being tacked up), but what I’m most curious about is at how early of an age would a horse begin weaving, and why would he pick that over some other habit—is weaving simply something that just “felt right” to him, when he was scanning the stereotypy catalog? Is it the kind of thing where one kid might start chewing her nails in class while the other taps his foot? And, while I’m on the topic of foot-tapping, are some horses more “rhythmic” than others? I know this might sound strange, but I’ve noticed my horse sways ever so slightly (though not with his head/neck) when his feet are being handled by the farrier. It reminds me a little of the YouTube video of the horse bobbing his head to a song on YouTube, for instance, only not as charming (to the farrier, at least!).

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A. Weaving is a rhythmic swaying in place that usually involves a lateral excursion of the head and neck and a concurrent shifting of weight between the front feet, such that the entire front end of the horse is usually involved, as well as sometimes the hindquarters. Usually the horse does this standing right at the stall door. A number of researchers are working hard to better understand weaving in horses but realize our knowledge of all stereotypies is ever evolving. Always remember horses are built to walk and eat and have social relationships, and when these are thwarted, behaviors that we find undesirable or disconcerting can result. 

Why did your horse "pick" weaving out of the catalog? Weaving and other locomotory stereotypies seem to be associated with the urge to walk, forage, and socialize. In part, we think this because one thing that seems to reduce weaving is the placement of a mirror in the horse's stall. Increasing visual or physical contact with other horses and optimizing turnout time also can reduce weaving. And, interestingly, bedding on straw may reduce weaving, perhaps because the horse can forage on straw when other feed isn't available. So this is opposed to an oral stereotypy suck as cribbing, which we tend to link with early (like creep feeding) and contemporary high concentrate diets more than thwarted movement and socialization. 

Many believe that the genesis of stereotypies is some management factor or stressor in young horses, often around weaning time and around the 2-year-old mark when early training begins. Certain diet and feeding regimens (such as high concentrates and limited foraging) seem to be a common factor in the development of stereotypies. Weaving specifically has been associated with foals weaned alone, in a box stall, as opposed to a group-weaning scheme. I saw one study that reported 60 months (5 years) as the median age for weaving to begin. Obviously, not all horses will develop a stereotypy even though exposed to early "risk factors." Genetics, predispositions, and intervening management all might play a role. 

Researchers think more proximate triggers can be any one of the following, as you have already experienced. A big factor is predictability in routine and his ensuing anticipation of an activity. Another is a too short duration of a rewarding or natural activity, such as turnout or feeding, so he will weave after these events are over. Another is frustrated access to something he wants, such as exercise or social contact.

Early on, there could be a learned element, such an inadvertent reward when he's weaving. Then the horse weaves because of anticipation or frustration. Finally, the weaving becomes "emancipated" from any specific triggers and, perhaps as you are seeing, he just does it with no apparent trigger at all. Remember too, all stereotypies seem to become internally rewarding to the horse.

In summary, the origin of the weaving might have been long ago and, as such, is well out of your control. Trigger factors might be hard to identify and not feasible to really change. There are management schemes that could serve to reduce the urge to weave.

As far as the subtle swaying with the farrier, it could be that is your horse's manner of weaving with a foot held up in the air. But I always have to consider a horse that shifts or sways when one foot is held up that maybe there's some discomfort either with flexion of the up leg, or more weight-bearing on the other legs. Not a red alert, just something to tuck away for future reference.

About the Author

Nancy Diehl, VMD, MS

Prior to attending veterinary school, Dr. Nancy Diehl completed a master’s degree in animal science while studying stallion sexual behavior. Later, she completed a residency in large animal internal medicine at the University of Pennsylvania’s New Bolton Center and worked in equine practices in Missouri and Pennsylvania. Diehl also spent six years on faculty at Penn State, where she taught equine science and behavior courses and advised graduate students completing equine behavior research. Additionally, Diehl has co-authored scientific papers on stallion behavior, early intensive handling of foals, and feral horse contraception. Currently she is a practicing veterinarian in central Pennsylvania.

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