Shannon Tieke purchased shadow, a 4-year-old Quarter Horse, three years ago as a pasture buddy for her Palomino, who was living alone at her Lafayette, Indiana farm. At the time, Tieke admittedly didn't have a whole lot of horse experience. That's why she was taken aback by her new horse's habit of latching onto his feed bucket with his front teeth and making a hollow, gulping sound. After all, she'd had her other horse for several years and had never seen this behavior before. She wondered if there was something wrong.
Shadow, like an estimated 5% of horses, is a cribber.
A cribbing horse grasps a surface with his incisors, flexes his neck, and swallows air. As the air passes through his throat, it makes a gasping, grunting, or groaning sound.
Sink Your Teeth into Cribbing Research
- Genetics, diet, personality, and weaning methods seem to play strong roles in determining whether a horse will crib.
- Horses are unlikely to learn to crib from other horses.
- Cribbing can pose an increased risk of colic.
- Regular turnout and a forage and oats-based diet can reduce the frequency of cribbing.
- Cribbing collars and muzzles can stop horses from cribbing, although
- experts disagree about whether we should try to prevent cribbing around-the-clock.
The behavior can be hazardous to the horse's health, and there is no "cure" for the condition. Once a horse starts to crib, he might feel the need to latch onto any surface in his reach. Most often, horses will crib on fence boards, stall doors, and feed tubs. Auburn University professor and Extension horse specialist Cindy McCall has even had reports of horses cribbing on crossties in a barn aisle and-one particularly determined cribber-on his own shoulder.
There are ways to manage a horse's cribbing, and research is underway to better understand and work with cribbers.
In reality, a horse doesn't crib because he wants to be a bad horse. Some researchers now believe that horses do it to relieve pain, anxiety, or frustration.
Researchers call an activity that's repeated without variation and without goal or function a "stereotypic behavior" or "stereotype"-which more accurately describes a horse's need to crib.
"They're really highly motivated to crib. They will work as hard to crib as they will for food," says Katherine Houpt, a professor of behavioral medicine at the Cornell University College of Veterinary Medicine.
Research into endorphin levels-the "feel good" chemicals in the bloodstream-has not yielded consistent results as to whether cribbing horses actually get a high from their actions.
One possibility Dr. Houpt suggests is horses might not crib because of the endorphins; rather, the endorphins that are already present from another source-such as a type of feed-might be a cause for the action.
What kicks off a horse's cribbing behavior may be fairly complex.
"There are a range of risk factors that come together, so personality, breed, diet, early experience-including weaning method-all have a role to play," says Dr. Daniel Mills, a well-known equine behaviorist who is researching stereotypes at the Royal College of Veterinary Surgeons in the United Kingdom.
A primary factor in determining whether a horse will crib is the breed. Thoroughbreds are the number-one breed for cribbing, with 8% of them exhibiting the behavior. Quarter Horses are next most likely. Evidence points to a genetic link for cribbing.
The belief that horses learn to crib from other cribbers is untrue, says Dr. Houpt. Research shows only 10% of cribbers pick up the habit from others, and those horses were probably genetically predisposed.
"It starts usually at weaning or when you change the horse's diet. When you bring him off of pasture, stick him in a stall, and give him sweet feed, that continues to be the main stimulus," according to Dr. Houpt.
The role that sweet feed plays in triggering cribbing is still unknown. Feeding straight oats, however, seems to decrease the frequency of cribbing in horses exhibiting the behavior.
Dr. Mills believes half of all cribbing horses start within 20 weeks of age, the typical weaning period. There are so many variables-change in feed types, change in feeding routine, often a change in environment, and stress-that it's difficult to exactly pinpoint the cause. Cribbing has not been reported in wild horse populations, strengthening the idea that humans' management of horses may be to blame for the behavior.
Weaning horses using careful management can reduce their likelihood of becoming cribbers: "Ensuring good turnout, gradual weaning, and minimizing the use of concentrates, especially early in life," can aid in prevention, says Dr. Mills.
The idea that horses crib because they're bored may also be untrue. Dr. Houpt has found that enriching their environment and providing regular exercise isn't a help. Other experts disagree, saying cribbing horses that receive regular exercise and other types of environmental stimulation, such as mirrors and toys, are less likely to crib.
Some horses are naturally more anxious and stress prone, and Dr. Mills says that could be a predisposition for cribbing. In fact, the behavior is least often found in cold-blooded horses such as ponies and draft breeds, which tend to have less worrisome personalities.
There is some disagreement among researchers over whether a horse receives a physical or mental benefit from cribbing.
As far back as 1888, researchers hypothesized that horses cribbed because of stomach upset. They treated them then with blocks of salt and chalk in feed mangers and magnesium and ground oak bark on the feed. In his research since the late 1990s, Dr. Mills has explored this theory further. He treated cribbing horses with antacids and found this might significantly reduce the behavior. His team's research is ongoing.
At the same time, Christine Nichol of the Centre for Behavioral Biology at the University of Bristol in the United Kingdom found an association between gastric ulcers and cribbing. Studies by other teams of researchers, including several to which Auburn University's McCall has contributed, also link gastric ulcers with cribbers and show a lower gastric pH in cribbing horses, indicating they have a more acidic gastric environment.
McCall and her research teams have found the act of cribbing produces saliva. Other than that production, though, cribbing horses tend to produce less saliva throughout the day.
McCall says they haven't reached a conclusion as to whether cribbing causes stomach issues or whether the presence of stomach issues is the impetus for cribbing.
There is not much that can be done to ward off cribbing behavior once it's started. "The only horses I could cure were the horses that had just started," Dr. Houpt says. That was by letting the horses out of their stalls and putting them back on pasture.
"Once it has been going on, it's very hard to stop, even if you make the environment perfect, although the rate at which horses become cribbers will be less when they're on pasture. If you feed them nothing but hay and oats, they will crib at the lowest rate," Dr. Houpt says.
In addition to adjusting the horse's environment, there are other options for enriching a cribbing horse's environment and managing his behavior:
Forage. Horses kept on pasture and those with free-choice access to hay may crib less.
Antacids. If cribbing really is related to ulcers, providing an antacid in a horse's diet could be beneficial.
Cribbing collars. Dr. Houpt says these popular neck collars do seem to work, but "you have to make it so tight that often the horse develops lesions." Fitted around the horse's jowl at the throatlatch, a cribbing collar doesn't affect a horse's breathing, eating, or drinking when he isn't attempting to crib. When the horse does attempt to crib, the collar applies pressure to the throatlatch so he can't arch his neck and suck in air.
Shock collars. Both the kind that automatically shock the horse when he flexes his neck and those that are controlled by people via a remote control often are viewed as cruel. Their effectiveness has been debated.
Cribbing muzzles. Muzzles do work, although horses will try their hardest to remove them. A metal and nylon muzzle clips to the horse's halter and allows the horse to graze and drink, but the horse can't get his mouth around a solid object to crib.
Cribbing rings. "They're copper hog rings that you put around the horse's teeth so they can't make contact with the fence. It works, but they don't stay in very long, and it does slow down their grazing," says Dr. Houpt, who has used these in her research.
Premises paint. Several wood coatings are produced with the intention of preventing cribbing. Some people swear by using grocery-store hot pepper sauce. But they may not always do the trick. Tieke found the pepper sauce she painted on Shadow's feed bucket wasn't a deterrent at all.
Modified Forssell's procedure. A surgery designed to prevent cribbing is the modified Forssell's procedure. A surgeon cuts muscles and nerves in the horse's neck and removes some muscle tissue. This makes it difficult for the horse to arch his neck and suck in air.
Experts differ in their opinions on whether to let the horse crib because it's a hard-wired behavior or to prevent the cribbing. "I would generally say, unless the horse colics recurrently, that it's better to allow him to crib than to prevent it through collars or surgery," says Dr. Mills. "These interventions do nothing for the motivation."
Some experts think the dangers posed to the cribbing horse require management. Others say cribbing should be reduced using a cribbing collar, but the control should be removed for short periods of time so a horse can occasionally act on his need to crib without incurring too much physical damage.
Cribbing horses can damage equipment and facilities with their grasping and pulling behavior. Shadow has torn down numerous feed buckets that were bolted to the stall wall and even broken a wheelbarrow that was within his reach. "They pull so hard, it's like exerting 125 pounds of force every time they flex their necks," Dr. Houpt says.
The real dangers, however, are the dangers that the horse poses to himself. "Cribbing does present a big risk factor for colic," said Dr. Houpt.
She hasn't found a direct correlation between the frequency of cribbing and the risk of colic, although she has lost one-third of the cribbing horses she has studied due to colic.
Cribbers also wear down their front teeth. They'll crib on any solid surface, very often including metal surfaces.
Cribbing horses tend to build thick necks from flexing their neck muscles so often. Many also appear thin. "Our skinny ones are skinny because they'll crib at the expense of eating," says McCall.
"We have a lot of researchers working on cribbing. It's going on worldwide," McCall says.
"I'm sure that within the next three to five years, we're going to find the gene for cribbing," Dr. Houpt says.
Medications have not been a successful method for control so far, but by finding the gene responsible for cribbing, the proper protocol should become clearer.
"I think there are some exciting developments, and with the right investment, we could gain much greater insight," says Dr. Mills. "If it was a physical disease that was affecting 5% of the population, you could be sure people would see the welfare significance. But because it is thought of as an endemic problem of the horse rather than a welfare problem, there is very little funding. And what research has been done has largely been done by self-funding, dedicated individuals."
Until there is a definite method for eliminating cribbing, horse owners must be diligent in managing the behavior. "It's not that he is an evil horse, it's that he's been afflicted with this genetic problem, and it's up to you to try to maintain an environment where he's least likely to crib," Dr. Houpt says.
Many cribbing horses make wonderful equine partners as performance and trail horses. "If the horse is functional otherwise, you've got to work with it," McCall says.
When raising a horse from birth, owners should pay special attention to the environment and management surrounding the foal's weaning experience to reduce the likelihood that such stereotypic behaviors as cribbing become an issue