Are cribbers better competition horses?

Cribbing is the most common stable vice, or stereotypy. It is where a horse grasps a solid object, such as a stable door, and inhales air. It is usually a stress response to management conditions.

What makes cribbers different?

A small bundle of nerve cells in the horse’s forebrain known as the nucleus accumbens (NA), and an even smaller group of cells in the midbrain known as the ventral tegmental area (VTA), are key regions responsible for controlling behaviour.

In response to events that horses find naturally rewarding, such as eating, the VTA releases a chemical messenger, dopamine, which binds to docking sites within the NA known as dopamine receptors. It is thought that this binding effect may well be what produces the feelings of pleasure.

In humans, repeated activation of this system by illicit drugs such as cocaine causes such receptor sites to multiply and become more sensitive.

Interestingly, laboratory-based experiments indicate that where the dopamine receptors are concerned, brains from cribbing horses show similar alterations to those of people who have taken cocaine.

Cribbing is therefore likely to have rewarding consequences for the horse and, in this respect, could be used to counter the effects of stress.

Training cribbers

Young horses learn through trial and error. A stimulus, such as leg pressure, motivates a range of responses, one of which will be correct.

Through the timely delivery of a reward, a good trainer will bring about precise activation of the NA and appropriate brain stimulation, which encourages the responses that we need in a competition horse.

Masters students at the Royal Agricultural College in Cirencester, United Kingdom,  set up an experiment to assess whether there was any difference in the way cribbing and non-cribbing horses tackled a simple task and learned from it.

Ten cribbers and 10 “control” horses had to select a large playing card marked with a circle and ignore one marked with a cross in order to obtain a food reward.

Cribbers required fewer tries to reliably select the correct card. However, when the cards were switched, cribbers took much longer to cotton on.

So, if subjected to excessive repetition and positive reinforcement, cribbers seem to become quite fixed in their response and can find it difficult to progress to more complex tasks.

It must be stressed that buying horses that crib should not be discouraged. In fact, aspects of their behavioural repertoire could be favourable.

Translated into an everyday competition scenario, whether this is teaching a new dressage movement or negotiating a technical cross-country fence, a cribber’s ability to react quickly to his rider’s instructions could be a help rather than a hindrance.

Horse and Hound, 3 September 2009

1 Response

  1. I have a OTTB cribber, he is a “steady eddy” out on the trail, and wonderfully responsive in the schooling ring. In researching, I found that it is an endorphin release, he mainly does it after eating. Some genetic lines are also prone to it. I give Boss as natural environment as possible, with room to run, a shelter, other horses for company. He’s worth having around!

Leave a comment

Time limit is exhausted. Please reload CAPTCHA.