IT MIGHT BE HARD to find a nail in a haystack, but sometimes horses do just that — with unhealthy results.

Consider the case of the horse in Indiana that apparently swallowed a shoeing nail with its feed. The nail sat in the animal’s intestinal tract for a long time, perhaps years, without puncturing  any organs. The horse’s system gradually built layer upon layer of a hard shell on the nail, and eventually the nail was encased in what amounted to a rock.

“It’s called an enterolith,” says Nickie Baird, a veterinarian at Purdue University in West Lafeyette, Ind. He notes that enteroliths can grow around any foreign object (shoeing nails are an uncommon source) or even without one.

A Recurring Problem

“Eventually in such cases, the horses show signs of colic,” Baird says. “While these horses might require surgery the first time they colic, more often they experience recurring colic episodes.

“The enterolith acts like a ball valve, obstructing the large intestine, wedging in a narrow point in the digestive tract. The flow of feedstuffs is blocked by the obstruction. Many horses respond to treatment with pain medication and mineral oil to loosen up the feces, and everything seems fine.

“The enterolith may fall back down into the dorsal colon and open up the pathway, and the horses will go on about their business,” Baird notes. “But a week or a month or so later, they may colic again. It’s not unusual to see a horse do that two or three times.

“Usually at some point, the enterolith gets wedged in there to the degree that it’s not going to drop back out, and it’s a complete obstruction. Then the horse will feel more and more pain and become more distended, and surgery is needed,” Baird says.

“Sometimes we open up a horse and find two or three of these things inside. We had a horse here with two of them, and they both had gotten flat on one side from rubbing against each other for so long.”

The long-term presence of enteroliths does not mean they should be taken lightly, Baird says, because they can lead to serious discomfort and death.

Severe obstructions caused by the enterolith being wedged tightly in the intestine can lead to a rupture of the intestinal wall and fatal gross contamination of the abdominal cavity with feces. Symptoms in such cases include a heart rate in the 90s and sweating. The horse might thrash about or throw itself to the ground.

In milder cases, the heart rate reaches the 60s, and the horse rarely thrashes. “It’s a blockage that won’t let feedstuffs through,” Baird notes. “The horse gets uncomfortable because it’s getting full.”

Farrier Advises Caution

Farrier Jim Keith of Wingate, Ind., brought the case of the Indiana horse to the attention of American Farriers Journal after learning about it from Baird.  Keith said the case demonstrates the importance of horseshoers cleaning up after themselves, especially sweeping up shoeing nails.

“A lot of farriers are excellent about this, but some think it’s not their job,” says Keith. “They think it’s work for the stable crew. Personally, I was raised to believe that if you make a mess, you should clean it up. It should be a part of your service.”

Keith points out that hand-held wand magnets and rolling magnets pick up loose nails better than brooms and are widely available.

Nails found on the ground have usually been pulled off a horseshoe or been scattered when old shoes were removed, Keith notes. “Those nails are bent and they’re more likely to stand up, with points waiting to stick into a soft surface,” he says. “The horse in this radiograph had swallowed an old nail; thankfully it didn’t have a bent clinch or it could have caused even worse problems.”

Baird says horses don’t often swallow nails, though foreign objects in the intestines are fairly common. He recalls a surge in such cases a few years ago, when rubber fencing made from old auto tires was gaining popularity.  Horses chewed on the rubber, swallowing the indigestible radial cords, many of which became enteroliths.

Enteroliths also are more common in California, he says, possibly because of the presence of grains of sand that can be ingested.

Horses provide their own defense against swallowing foreign objects, Baird notes. “If a horse is really hungry, it might gobble down its hay or grain, and then this can be a problem,” he says. “But usually, if they’re just grazing, they’ll do a good job of sifting through their food. Still, it’s a good idea if we can help them with a bit of caution.”