Crib-Biting & Windsucking.
‘Vice’ is a word commonly used to describe an undesirable behaviour performed by horses and ponies. There are a range of different vices with multiple causes and treatments. This article will provide an overview of crib-biting and windsucking, covering the causes and some of the treatments. Other vices will be covered in other articles.
Crib-biting and windsucking are two closely related vices, which are not always confined to the stable. Crib-biting is characterised by a horse which will bite onto a surface, most often wood, and then suck in air. Windsuckers are very similar but they do not necessarily need a surface to bite onto in order to perform the sucking action. 
Classic signs that there is a ‘cribber’ on your yard will be chewing marks on wooden items, in extreme circumstances there may be chunks out of doors and fencing. Another common sign that your horse is crib-biting is abnormal wear to their front teeth. The action of biting the surface can cause the bottom of their top incisors to become angled rather than straight.
There are currently a few causes of crib-biting which are known. Firstly a horse may initially begin crib-biting if they are suffering from a nutritional deficiency, this is usually due to the horse not having enough access to forage, and therefore an acidic gut. Another cause could be boredom, mainly with horses that tend to be confined to the same spaces over extended periods. Crib-biting can also be induced by stress, this can be as a result to changes in environment or management routines. However, regardless of the initial cause it can quite quickly become a deep set behavioural issue, meaning that even if those causes that began the vice are resolved, the horse may continue to crib. This can be the case in some horses as crib-biting releases endorphins in the brain, even if the trigger is removed, the horse will still continue with the behaviour to get the same feeling.

Some believe that crib-biting is a behaviour which can be learnt through imitation, we do not believe that this is true. Whilst having a crib-biter on your yard does not necessarily mean that all of the horses will begin cribbing, it does mean that they may be a predisposed to learning the behaviour if they are exposed to any of the other causes.
Treatments and Preventatives
If your horse is crib-biting purely due to a nutritional deficiency, then correct supplementation of its diet should be enough to resolve the issue. If you are unsure how to go about this then the best thing to do would be to speak to nutritionist, feed or supplement company who may be able to advise further. 
A basic treatment for crib-biting is to minimise the number of surfaces on which the horse can crib. This can be done in a few different ways for example, you can place metal strips across the top of wooden stable doors or the wood can be coated with substances designed to give the wood a bad taste (products like this can usually be found at your local tack shop). Both of these methods should put the horse off continuing to crib. You can also buy a cribbing collar which could stop your horse cribbing.
A basic preventative measure is to try and make your horse’s environment more interesting to keep boredom at bay. This could involve making sure they always have a companion, or you could provide them with one of the many boredom busters on the market. Boredom busters are designed to keep your horse occupied either in the stable or in the field (depending on the product), however if you cannot afford one of these items, then often a football or a swede on a string can be a good substitute. 
It should be noted that some treatment methods can cause the horse to display other stereotypical behaviours, for example box walking, so the best way to prevent your horse from displaying these behaviours is to talk to a nutritional advisor or to take away the stress trigger.
Please note that this piece has not been written as a comprehensive list of the signs, causes and treatments/preventatives of crib-biting and windsucking. It is simply here to provide a little background on the vices.
As always, if ever you are at all concerned about your horse’s health and wellbeing, please do consult your vet.
Further Reading:
Veterinary Notes for Horse Owners. Hayes, H. (2002).