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hormone gastrin, which is a stimulator of hydrochloric acid (HCL). When the horse has a meal with stomach stretch and protein in the diet, this stimulates production of gastrin, which in turn stimulates the parietal cells to produce HCL, making the stomach more acidic. In our cribbing horses there was a tendency toward a heightened gastrin response after feeding grain, compared to the non-cribbing horses,” she says.
“Since that study (in 2008-2009), another paper came out in 2012 from a research group that was looking at additional gastro- intestinal hormones in cribbing horses. They were looking at ghrelin and leptin, which are both tied to satiety (the feeling of being full and satisfied after eating). There were some differences between stereotypic and control horses, but when the same group of authors repeated that study in 2013, in the second group of horses they didn’t see significant differences. So this idea needs further investigation,” says Wickens.
RECENT RESEARCH
The traditional theory has been
that horses start cribbing as a coping mechanism. Recent studies have shown that when horses are allowed to perform stereotypic behavior there is reduction
in the stress hormone cortisol and/or
heart rate. Some researchers have seen a difference between cribbers and the control horses that do not perform stereotypic behaviors, while other researchers have found no difference.
“An abstract was presented a few years ago at the Equitation Science Society Conference, in which the study looked
at cribbers and non-cribbers that were all exposed to a stressor. The cribbers were divided into two groups; the researchers either prevented or allowed the cribbers to go ahead with their crib-biting activity during the stressor or immediately after the stressor. The study found that when the horses were allowed to crib, they were less stressed,” says Wickens. It relaxed them for a while.
This Swiss research group found that cribbers allowed to crib during training (using a wooden plank near where
they were being trained in hand, doing groundwork) had reduced stress levels, whereas their stress levels remained high when they were not allowed to crib. The study results suggest that cribbing is a coping strategy that helps these individuals reduce cortisol levels caused by stressful situations. The researchers concluded that preventing stereotypic horses from cribbing could be an inappropriate strategy to
control this behavior, as it prevents these horses from coping with situations that they perceive as stressful.
This is something for owners to think about, if cribbing is a coping mechanism. “As concerning as the behavior can be—with the noise, destruction of facilities, etc.—if
it does serve some function and has some purpose for the horse, we need to be careful about the way we approach it in terms of managing these horses. We also need to look at the broader picture and how we manage horses, especially young horses, to try to keep this from happening in the first place. This is important for young horses in training that need more calories, being fed concentrate feeds,” Wickens says.
It might be best to get the extra calories into them with more fat and fiber and less starch/sugar. “This also tends to have a calming effect (they aren’t as hyper) when there is more fat and fiber and less sugar. Many commercial feeds contain highly digestible fiber sources like beet pulp and alfalfa meal. These can provide more calories and help maintain body condition without creating behavioral and health issues like colic and laminitis,” says Wickens.
The behavioral issue also goes back to the question of best management for a cribber. “Should we be trying to thwart this behavior? The thought today is that maybe we should not try to halt it, unless the cribber is a hard keeper and spends too much time during meals cribbing instead of eating. If the horse
is not consuming enough calories to maintain body condition, he might need to wear a collar during mealtime so he can focus on eating instead of cribbing,” Wickens says.
“A 2017 article by Katherine Houpt and Julia Albright focuses on dietary taste and gastric stimuli in terms of how it relates to a highly palatable meal containing sweet feed with molasses and a higher sugar content. This may stimulate cribbing behavior. We do see more frequent cribbing during a grain meal. Horses tend to increase cribbing during or right after a grain meal. Very palatable feeds seem to stimulate them to want to crib, and they don’t crib as much while eating forage.”
A strategy that has met with some success is to make sure the horse has already had some forage before being given a grain meal. If you leave some hay in the stall when giving the grain meal, it may also help. It won’t stop the cribbing, but may give the horse something else to focus on when he finishes his grain.
Another recent study looked at providing cribbing horses with toys. Lick-it type toys can give the horse something to do and distract him from wanting to crib. “One toy is called
a tongue twister, designed for a horse to chew
If a cribbing horse is a hard keeper and has a history of colic or other health issues such as severe wear of their incisor teeth, Wickens suggests putting a collar on that horse during mealtime or when it is in a stall.
EQUINE HEALTH
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