Management Considerations for the Cribbing Horse
August 5, 2015
Without knowing the exact cause for cribbing behavior in horses, prevention can be difficult, explains Dr. Sara L. Mastellar, SDSU Equine Instructor.
"Horses that crib may spend anywhere from 15 to 65 percent of their day performing this stereotypy and approximately 4.4 percent of horses in the US are cribbers," Mastellar said.
Cribbing is a stereotypy or seemingly functionless repetitive behavior performed by horses which is characterized by grabbing an upright object with the teeth and pulling against the object with an arched neck and sucking air.
Causes of Cribbing
Cribbing has not been reported in feral horses that are free ranging explained Mastellar. "Therefore it is possible that aspects of management may cause the cribbing behavior," she said. "Specific causes of cribbing are yet to be determined and the behavior may be due to a combination of factors. Diet, genetics, boredom, stress, and copying another horse have all been suggested as causes of cribbing."
Below, Mastellar discusses possible causes as well as ways horse owners can curb cribbing.
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Horses that have more grain in their diet have been shown to be at an increased risk of developing stereotypies. "While research shows that increased roughage in the diet has been associated with a decreased risk of developing stereotypies," Mastellar said. "This holds true for cribbing, as one study found that feeding concentrate to young horses immediately after weaning was associated with a four-fold increase in manifestation of cribbing."
Mastellar added that the study showed that the type of grain seems to play a role as horses fed sweet feed have been known to crib more than horses fed oats.
Whether or not horses learn cribbing behavior from horses that already crib has not been substantiated. In a survey of horse owners, only 1 percent of horses were reported to have developed a cribbing habit after exposure to another cribbing horse, which Mastellar said makes it appear that horses are unlikely to learn cribbing behavior from one another.
Genetics could also play a role, as Thoroughbreds and warmbloods are more likely to crib compared to other breeds. "A study of horses in Finland found the heritability of cribbing has been estimated at 0.68, which means that cribbing is likely to be passed onto offspring," she said.
Potential ramifications for the cribbing horse
Horses that crib will have increased wear on their incisors. This wear may not cause problems for the horse until they are older and those teeth become in danger of falling out, Mastellar explained. "The additional wear on these teeth may ultimately shorten the life of the horse because they are not able to eat as effectively without these incisors," she said. "Additionally, cribbing horses may be harder keepers due to spending time cribbing instead of eating and the increased energy expenditure through the act of cribbing."
Cribbing is a risk factor for a variety of conditions. Most notably cribbing horses are at risk for colic. Additionally, Mastellar said it has been found that cribbing horses are more likely to have stomach ulcers than non-cribbing horses. "Cribbing is even a risk factor for equine motor neuron disease. All of these issues contribute to the unpopularity of cribbing horses and a potential reduction in market value," she said.
Preventing the onset of cribbing behavior
Cribbing manifests in young horses, Mastellar explained, typically around 20 weeks of age. "Many of these horses exhibited wood chewing behavior before manifestation of cribbing," she said.
Reduced risk of cribbing is associated with increased time spent outside, social contact with other horses and keeping foals solely on grass through the weaning process. "Once cribbing behavior is established, it is unlikely that a horse will ever completely cease to exhibit the behavior," she said.
Cribbers are different
There are some studies that suggest that cribbing horses may have some physiological and mental differences from their non-cribbing peers.
Horses that crib may also have atypical hormone levels when compared to non-cribbing horses, Mastellar explained. "They have lower plasma levels of leptin, which is a hormone in regulating appetite and the reward center of the brain. These horses were also found to have higher circulating levels of gastrin, a hormone involved in triggering the production of stomach acid ," she said.
These hormone levels may explain differences found between cribbing and non-cribbing horses in learning and stomach ulceration.
Horses that exhibit cribbing behavior may react to situations differently than their non-cribbing counterparts. One study suggests that cribbers learn differently than non-cribbing horses. However, owners responding to a survey reported that cribbing horses had less anxious temperaments and were equally trainable when compared to non-cribbing horses. "Another study found that cribbers tend to engage in oral activity when stressed, whereas non-cribbing horses toss their heads or paw when similarly stressed," Mastellar said.
When the cribbing horses were prevented from cribbing, some engaged in other oral activity.
"Cribbing may be a way that these horses cope with stress. Cribbing horses actually experience a slowing of heart rate during cribbing. Levels of plasma cortisol, a hormone associated with stress, in cribbers was found to be greater than that in non-cribbers," she said.
Mastellar added that researchers have conflicting opinions as to whether or not preventing a horse from cribbing is stressful for the horse.
"These differences should be considered when developing a management plan for these horses," she said.
Managing a horse that cribs
The decision on whether or not to inhibit a horse's ability to crib should weigh the possibility of increasing stress on the horse against the risk of colic and other health issues associated with cribbing, Mastellar explained. Many managers also consider the destructive nature of cribbing behavior on barns and fences.
"Cribbers are motivated to crib and will work as hard for an opportunity to crib as they will for a chance to eat sweet feed," she said. "This motivation makes keeping an established cribber from engaging in cribbing behavior particularly difficult."
Many horsemen have tried to prevent horses from cribbing and their creativity can be seen through the sheer variety of methods for preventing a horse from cribbing.
The characteristic cribbing collar is the most commonly used method. These collars generally consist of two straps. One goes in front of the ears and the other behind. The straps hold in place a piece of galvanized steel under the horse's neck. "With the piece of steel in position, it is uncomfortable to flex the neck and perform cribbing behavior," Mastellar said.
She added that care must be taken that the collar is properly fitted to reduce tissue damage. "Cribbing collars are effective in preventing cribbing in most horses, but they are only effective when the horse is wearing the collar," she said.
Hard Habit to Break
Horses that are allowed to crib, after being prevented from cribbing for some time, will have an increase in cribbing rate compared to before they were prevented from cribbing. "It's as if to make up for lost time," Mastellar said.
Feeding management is another way that the horse's manager can affect how often a horse cribs. "Cribbing rates increase after a concentrate meal, so if possible, formulating diets that contain more forage and less grain can help to mitigate cribbing behavior," Mastellar said.
Although feeding horses little and often is recommended, Mastellar said cribbing horses fed many small concentrate meals may actually crib more because cribbing is associated with feeding time. "They actually fixate on the feeders and spend more of their time cribbing," she said.
The energy and time spent cribbing may make them harder keepers than other horses. Excessive tooth wear may also affect the ability of older cribbers to utilize their diet.
Cribbers should have access to turnout and the opportunity to socialize with other horses. Although, cribbing behavior is not eliminated by providing turnout and companion horses, Mastellar said research shows that cribbing rates are reduced. "Some cribbers are isolated for fear of the behavior spreading to other horses. It is unlikely for one horse to learn cribbing from another and the cribber's welfare will benefit from having other horses with which to socialize," she said.
If there is a need to keep a cribber stabled, providing a toy has been shown to reduce cribbing rates slightly. Turnout, socialization, and prevention of boredom are all forms of stress reduction for these horses.
Other methods of preventing cribbing that are effective, but require intensive management include: elimination of cribbing surfaces, taste deterrents, electrification of cribbing surfaces, pharmaceuticals, oral antacids for foals, surgery, and increasing the time spent eating.
Take home message
Cribbing in horses is likely a permanent behavior pattern once established. "The exact cause of cribbing in horses remains to be determined, but may be related to management, nutrition, and genetics. Therefore, consider not breeding to a horse that cribs, providing plenty of forage at weaning, and allow horses plenty of turnout and interaction with other horses to reduce the chances of a horse becoming a cribber," she said.
Cribbers are more prone to certain health issues, including colic. They may have differences in their learning and how they cope with stressful situations when compared to non-cribbing horses. Due to this, Mastellar said a horse owner's decision to inhibit a horse from cribbing should weigh the possibility of increasing stress against the possible health risks of cribbing. "Besides inhibiting cribbing behavior, a manager can adjust feeding and turnout conditions to reduce cribbing rates," she said.