The pretty bay mare who arrived at the University of Guelph equine clinic was bright, alert and didn't appear to be in any pain. Despite the newborn foal at her side, she was easy-going and friendly with the staff. Her vital signs were normal, and she didn't have an elevated temperature.
"She really looked fine," says Nicola Cribb, VetMB, DVSc, who admitted her and performed the initial examination. "She didn't seem to be bothered by anything." If Cribb hadn't already been told why the mare was there, she never would have guessed anything was wrong at all.
But, in fact, the Standardbred mare presented a potentially life-threatening problem: During a routine part of an examination for a mild colic the night before, she had somehow managed to bite off nearly 30 inches of a nasogastric tube, which now lay in her stomach.
"We had been given her history beforehand, but we still weren't sure what to expect," says Cribb. The previous day, only two days after foaling, the mare had developed some signs of colic. The farm veterinarian had treated her with flunixin meglumine and, suspecting an impaction, decided to "tube" her to check for reflux.
Nasogastric intubation is a routine and important procedure in colic cases. A nasogastric tube is a long, flexible hose that is inserted into a horse's nostril to the pharynx, the structure that serves as the entrance to both the esophagus and the trachea. Carefully, the veterinarian encourages the horse to swallow and then guides the tube down into the stomach.
In a case of suspected colic, this simple tool can provide both diagnosis and treatment: If fluids immediately gush out of the tube once it enters the stomach---a condition called "reflux"---the veterinarian knows that the stomach is not emptying, due to an impaction or possibly a stoppage of the gut called ileus. This release of fluids and/or gas also instantly relieves pain and lessens the immediate danger the horse is in.
The procedure is normally uneventful. Nasogastric intubation is one of the first skills taught in veterinary school, and it's something an equine veterinarian will do hundreds, if not thousands, of times in a career.
This time, however, was different. While the veterinarian was inserting the tube, the bay mare struggled and resisted. Unable to keep the tube moving down her esophagus, the veterinarian decided to withdraw it and try again once the mare settled down. But to his shock, the tube that he pulled out was only about half as long as what he'd pushed in---and the ragged edges on the end of the hose suggested that it had been bitten off.
Apparently, the tube had met resistance at the pharynx, and a loop had formed in the back of the mare's mouth that got caught between her back molars. A quick check of the mare's mouth, trachea and nasal passages confirmed that the missing section wasn't there: She had swallowed it.
Weighing the options
"Of course, this all occurred late at night," says Cribb, "which is always the way it seems to happen with horses." As the veterinarian and the owner discussed the situation in the darkened barn, the mare's colic signs resolved. Because she was comfortable, with strong vital signs, they decided to monitor her until morning, then ship her and her foal to the?university during the daylight hours, when it would be safer.
After her initial examination on admitting the mare, Cribb passed an endoscope---a long, flexible tube equipped with a light and a camera---down the mare's esophagus to look directly into her stomach. There, in clear view coiled up on the floor of the stomach, was the long length of nasogastric tube.
Leaving the tube in the stomach wasn't an option. "If it had been a very small fragment of tube with obviously smooth and rounded edges, we may have considered just leaving it or helping it along with mineral oil," says Cribb. "But what we saw was far too long to pass out on its own. Leaving it would have caused an obstruction or it could have traveled farther back into the intestines and possibly perforated them. All sorts of bad stuff could happen, so we knew we had to take it out."
Cribb, however, had no experience retrieving lost nasogastric tubes from equine stomachs. "This was the first case my colleagues and I had ever encountered," says Cribb. "We took some time to look into the literature and found only five other horses that had been reported on."
In two of those cases, the tube was not fully in the stomach and could easily be reached with an endoscope. In the other three, surgery was needed to access the tube. All the horses had survived, which was good news, but the downside was that all five had also been placed under general anesthesia, which can carry the risk of serious complications.
Cribb's team decided to let the bay mare lead them through various approaches to the problem. "We always try the least invasive procedure first," says Cribb. "Even though she'd managed to chew through one tube, she had been pretty calm with us, so we thought we'd try to retrieve it without anesthesia first, just sedation. If that didn't work, we could always escalate to doing it under anesthesia and even surgery if necessary."
Improvisation pays off
Cribb's next problem was deciding how to retrieve the broken tube. "It became a matter of trying to determine which instrument we could use to most effectively grab and bring it back up the length of her esophagus," she says. They also needed to avoid inadvertently lacerating or puncturing the stomach wall in the process. "There is no instrument made for this purpose, so we were going to have to improvise."
With some trial and error, Cribb sought the right combination of tools. First, she needed one of the longest endoscopes available---a little over six feet long---to reach the stomach. In addition to the camera and light, endoscopes are often equipped with a small channel that different instruments can be passed through so that a surgeon can manipulate the organs or tissues he is looking at.
With the mare under sedation, the team first tried to grab the tube with a style t fashioned into a loop, but they were unsuccessful. Next, they decided to try a snare. "Snares are simply wires shaped into a loop at the end and are often used in other types of surgery," she says. "For instance, if there was a cyst on the side of the uterus, you could use [the endoscope] to visualize it, then reach in and pull it off."
Cribb closely watched the endoscopic images on the monitor while she patiently tried to work the wire around a piece of the tube. "It was a bit like a strange video game," she says.
It wasn't an easy task, and she had to make multiple attempts. "The trouble we would have is that the tube would keep slipping back to the rear of the stomach, and then we couldn't see it," she says. Each time, blowing a bit of air into the endoscope inflated the stomach to bring the tube back into view so she could try again. During this process, another veterinarian monitored the bay mare to make sure her vital signs were steady and she wasn't getting overly stressed.
Finally, after an hour of trying, Cribb secured the snare around the tube. "Once we had it, it was pretty straightforward bringing it back up the esophagus," she says. "We had a bit of trouble directing it back out through the correct nostril, but that was easy enough to fix with some long forceps."
Cribb compared the recovered fragment to the top half of the tube, which had been brought in with the mare. The ends lined up perfectly, which assured her that the tube had been broken in only one place, and no stray fragments remained inside the mare.
Just to be certain, Cribb took a second, quick look around the mare's stomach with the endoscope. "I was looking for ulcers or other signs of trauma from her ordeal, but I didn't see anything," she says. "Her stomach looked perfectly normal." The mare stayed at the clinic another two days for observation before being sent home with her foal.
Cribb's experience with the bay mare was unique enough to inspire her to write up the case for a veterinary journal. "This was on account of the tube being recovered with the horse only sedated," she says. "We thought this was important to share, to let people know that while this type of accident isn't likely to happen, if it does, it doesn't automatically mean anesthesia and surgery."
And, as if fate was proving her point, Cribb has since seen three more cases of lost tubes---all of which she recovered without the need for surgery.
This article first appeared in EQUUS issue #429.