Cribbing is a compulsive behaviour practiced by some horses. It consists of the horse biting an object (such as a stall door or fence) with its front teeth, arching its neck while pulling against the object, and sucking in air. The reasons behind this behaviour are not fully understood, but it is believed that this activity releases pleasure brain chemicals (endorphins). In some cases, horses learn to crib (arch neck and swallow air) without actually grasping an object with their teeth. However, this is relatively uncommon.
Cribbing and wood chewing are sometimes confused. A cribber who bites a wooden object can leave teeth marks and damage which may look similar to wood chewing. However, the two activities are very different. In cribbing, the horse bites an object (wooden or otherwise) but does not eat it; in wood chewing the horse is actually nibbling on the wood. If one sees the horse perform either activity it should be clear which one the horse is doing as they are very different. If one does not see the horse doing either but only the damaged wood, then one can tell by examining the wood to see if the damage is due to a firm bite or if it has been nibbled away.
This behaviour has a number of negative health implications and needs to be corrected as soon as possible. Grasping and pulling on hard objects can wear down the teeth or damage them. The pulling motion, if frequent and intense, can result in abnormal muscle development (thickening) in the neck. Various other illnesses (such as colic) are associated with cribbing but it has not been established what the relationship is (e.g. does cribbing cause colic or are both cribbing and colic independent results of unnatural feeding regimes).
Horse cribbing is also known as wind sucking or crib biting.
Cribbing is not a natural behaviour but rather a compulsive habit. It develops as a result of boredom or anxiety or a combination of the two; although not all bored or anxious horses develop this habit. It is most often seen in horses which are kept in their box for long periods and who consequently lack mental stimulation.
There have been claims that if a horse cribs, other horses will sometimes watch and eventually copy the behaviour, becoming cribbers themselves. These claims have been neither proven or disproven. However, if true, it is another reason for treating and curing this behavior as soon as possible.
Some people also claim that pain (e.g. from colic or ulcers) causes cribbing. These claims are based on the observation that horses that crib have a higher frequency of colic and ulcers than the normal horse population. Although analysis of various cases confirms the observation, the research suggests an alternative explanation: horses that have an unnatural feeding regime (e.g. grain rather than pasture, 1 or 2 feeds per day rather than multiple) are more likely to get ulcers or colic and are also more likely to develop cribbing due to the associated lack of mental stimulation. In other words, colic does not cause cribbing and cribbing does not cause colic, but both can be caused by unnatural feeding.
Once the habit becomes ingrained, it can be very difficult to correct. As cribbing releases pleasure chemicals in the brain, it is effectively a drug addition, even though the chemicals are produced by the body. As with any drug addiction, kicking the habit is hard.
Part of the treatment is to move the horse to a more enjoyable environment which removes the boredom issue. For a list of actions, see mental stimulation. In particular, providing a maximum of pasture time is beneficial. Normally, over time, this reduces the frequency and intensity of cribbing, but typically it does not stop completely just from an environmental change.
In addition to addressing the root environmental issues, there are a number of actions to address the habit directly. Certain horses respond to one approach, some to a different approach. No single solutions is successful with all horses so you may need to try more than one of the following to see what works with your horse:
- Unpleasant tasting chemicals. Painting the objects which the horse bites to crib with an unpleasant tasting paint may be enough to deter the horse from cribbing, especially when combined with providing it with a more satisifying environment (e.g. lots of pasture time). There are a number of speciality products designed for this purpose, as well as a number of home made recipes. Make sure that any paint you used is veterinarian approved as some paints are poisonous.
- Live Fencing Wire. If your horse cribs on fences, puting fencing wire (with electrical current) along the top of the rails can prevent this.
- Cribbing strap. A cribbing strap (also known as a cribbing collar) is fitted around the neck, preventing the horse from swelling its neck to suck in air, or at the least making it difficult and uncomfortable to do so.
- Medication. Some owners have also reported good results with calming medication (especially anti-depressants). It is unknown if this is because of the stress reducing aspects of such medication or whether it is because they replace to some extent the endorphins associated with cribbing.
- Muzzle. Fitting the horse with a muzzle which allow it to eat (through the openings) but not to grasp rails or other structures.
- Surgery. In extreme cases, there is a surgical solution which involves cutting the muscles used to arch the neck. However, one would normally resort to this only after other solutions have failed and if the cribbing was a health risk.
It is adviseable to address the root problem of boredom and also take one or move of the above steps to correct the habit. A cribbing collar may prevent cribbing but unless the underlying problem (boredom, stress) is addressed the horse may simply develop alternative bad habits as it seeks to cope. Alternatively, providing a better quality environment will reduce the habit but on its own is unlikely to cure it. Consequently, a cure requires both environmental improvement and habit prevention.