Cribbing: Presumed Causes

Cribbing is a stable vice.
Cribbing is a stable vice. Unlike wood chewing, the horse grabs a surface with its teeth and inhales air.

Many horse owners simply won’t buy a horse that cribs. Partially it is because they are harder to board (some barns won’t take them). Other owners worry too much that a horse that cribs is more prone health issues (such as colic) or harder to keep weight on.

However, according to Cornell Veterinary School, cribbing affects approximately 300,000 horses in the U.S., including 2.5% of all Thoroughbreds so you are likely to come across one sooner or later.

I’d never thought about it much before I got Freedom. He was supposed be a short-term foster horse so when I found out he was a cribber, I didn’t care. Of course, he never left and over the past four years I’ve learned a lot about horses that crib. And I’m still learning because theories about why horses crib keep evolving.

What is cribbing?

Cribbing is when a horse swallows air which is why this vice is also called “wind sucking”. Usually, the horse grabs a stationary object (like a fence) with its teeth, arches its neck, tenses the muscles along its back and neck and sucks air into its esophagus. Typically the horse makes a strange grunting sound while the swallow the air.

It differs from wood chewing (another bad habit) in that the horse doesn’t actually chew on wood but cribbing horses can damage fences and wooden surfaces which is why many barn owners ban horses that crib.

Why do horses crib?

No one knows for sure why horses crib. One thing most people agree on is that it’s an obsessive compulsive disorder that is very difficult (if not impossible) to “cure”.

Here are some of the most common theories:

  • It’s a reaction to stress: sometimes horses start to crib when they are in intense training. Perhaps alleviating the gastric acidity caused by stress.
  • It releases endorphins: some people believe that cribbing releases an endorphin that gives a horse a natural “high” so that once the behavior is learned it is reinforced by a pleasurable sensation. Recent research disproves this theory.
  • It’s caused by boredom: virtually unknown among wild horses cribbing is a habit that only occurs among horses that are stalled. Certainly increasing turnout seems to decrease the amount most horses crib, but I’ve still seen cribbers out on grass that are cribbing on the fence.
  • It’s a learned behavior: people worry that stabling near a cribber will cause another horse to crib. I suppose this can happen but my cribber didn’t teach my non cribber the habit during the nearly four years they were stabled together, nor did the other three horses turned out with him pick up this habit. While many barns have one or two cribbers, it’s very unusual for other horses to pick up the vice.
  • It’s caused by dietary issues: horses on a high concentrate diet are more likely to crib.
  • It’s a reaction to pain in its stomach: many people think that horses crib to relieve the pain caused by ulcers or excessively acidic conditions. However, studies where horses were fed the antibiotic Virginiamycin, which increases the pH in the hindgut of horses made no difference in cribbing behavior.
  • It is a genetic condition. There are several factors that lend credence to a genetic predisposition to crib. Research conducted in Japan by Hosada in the 1950s showed that while cribbing rates across the equine population was less than 1%, in some lines of thoroughbreds the cribbing rate was as high 7%. For example 8.3% of the offspring and 6.4% of the next generation of the stallion Ryopan (a cribber) also cribbed. It appears that 25% of offspring of one cribbing parent and 50% of offspring of two cribbing parents cribbed. Similar results were discovered by Italian researchers Vecchioti and Galanti in 1986. They found that in a population of 1035 thoroughbred horses the incidence of cribbing overall was 2.4%. However, among certain “family” lines the incidence was as high as 44%.

My money is on a combination of genetic predisposition and environmental factors. We have two OTTBs at our barn right now and both crib even though they now have 24/7 turnout, free choice hay and have low concentrate diets.

Tune in tomorrow for more on the health issues associated with cribbing and ways to prevent horses from cribbing.

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