An Equine Eye Injury Mystery

What was causing a gelding's eye to water wasn't nearly as baffling as how it got where it did.
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During his first 14 years of life, Jake came to be known as an easygoing and reliable horse. The Rocky Mountain gelding seemed to get along with every-one and his levelheadedness helped him excel as a trail horse.

A healthy eye is clear and bright©any discharge is cause for concern.

A healthy eye is clear and bright©any discharge is cause for concern.

In fact, recalls owner Danielle Heistand, Jake remained unflappable even after a run-in with a porcupine. "We ended up having to pull quills out of his muzzle with a pair of pliers," says Heistand. "Even then, he just stood there while we pulled, and he recovered without a problem."

But Jake's no-drama nature would be put to the test after he developed a mysterious but persistent problem. It started in the summer of 2009, when the gelding's right eye began to water. What at first appeared to be a simple issue---a teary eye---turned out to be a problem that defied conventional diagnostic and treatment efforts and required some of the most advanced technology in veterinary medicine to finally be resolved.

Initially, the discharge from Jake's eye seemed innocuous. "It was just a watery fluid," says Heistand. "But the eye itself was clear and he didn't seem to be in any pain. We weren't particularly concerned at first."

But the tearing continued, and within a week the fluid took on a foamy appearance. Heistand called her veterinarian who, after performing a full exam, agreed that Jake didn't seem to be in much pain, nor was the globe of the eye damaged. The veterinarian suspected a blocked tear duct: Normally, the lubricating fluids the eye produces drain downward through a duct that empties through the nose. If that duct is obstructed, however, the tears can back up under the lower lid and spill down the side of the face. This problem is not uncommon and relatively simple to treat.

The veterinarian flushed out the duct and asked Heistand to call him back in a few days if the problem persisted. It did.

On the next farm visit, Jake's veterinarian still found no evidence of an eye injury, uveitis or any other problems. Concerned that the ongoing discharge might be a sign of infection, he prescribed an antibiotic ointment and asked Heistand to keep him updated. "Jake was great about the ointment," she says. "He just stood there as I put it in his eye three times a day."

But the treatment didn't seem to help. If anything, the foamy discharge was increasing.

On his third visit, Jake's veterinarian decided to increase the antibiotic firepower with a systemic assault. "The foam didn't smell bad like you'd expect an infection to," says Heistand. "But we really had no other clues. His eye still looked perfectly fine and he wasn't squinting or acting as if it hurt."

While he was on the systemic anti-biotics, Jake's eye did stop watering, only to start again when the course was complete. A second round of antibiotics followed the same pattern. By now, Heistand and her veterinarian were looking for any other possible explanation.

"We had a dog once that had gotten a wheat seed head lodged under his eyelid," says Heistand. "And his eye really watered and looked irritated. I suggested maybe Jake had something like that going on."

Other than the discharge everything still looked normal with a typical exam, so the veterinarian used an ultrasound probe to explore a little deeper. Still, he found nothing unusual. The non-invasive options available to him on the farm now exhausted, the veterinarian numbed the area and made a small incision through Jake's eyelid to look for a foreign object underneath.

"He found a blade of grass embedded in the tissues around the upper part of the eye," says Heistand. The veterinarian removed the grass and carefully cleaned the area. With a few sutures, Jake's eyelid was repaired, and he was started on a new round of anti-biotics. Everyone expected the issue was now taken care of. "I was pretty certain that would be the end of it," says Heistand.

But they hadn't yet discovered the real problem.

Probable cause
Almost as soon as the course of antibiotics ended, the discharge from Jake's eye returned. This time, however, it was thicker and creamier than before. And there were new signs of trouble---the eyelid began to swell, and Jake was getting sensitive about having it handled.

"At this point I think the veterinarian mentioned we might have to remove his eye," says Heistand. "But I knew that was the very last thing I wanted to do." Determined to exhaust all other options, Heistand decided to take Jake to Hagyard Equine Medical Institute in Lexington, Kentucky. They were met there by Marcos Santos, DVM.

"We knew he had a history of unexplained eye discharge, but that was about it," says Santos. "We did a full workup on him when he arrived, including an eye exam, and I remember he was a very friendly horse who was easy to work with."

With Jake sedated, the team at Hagyard used ultrasound to look at the structures around the eye, but, like the referring veterinarian, didn't see anything of note. They also took a series of head x-rays, which also turned up nothing unusual.

"It was then that we began to consider MRI," says Santos. Magnetic resonance imaging uses large magnets to produce images of internal body structures. Unlike radiography, which detects only bone and other "harder" surfaces, such as metal implants, MRI creates clear, highly detailed cross sections of both soft and bony structures.

But getting those images would entail some risk: For an MRI scan of the head, a horse has to be placed under general anesthesia for up to three hours. "You need to work quickly because having a horse out for that long can lead to muscle damage from the pressure of lying down," says Santos.

But Heistand was eager for answers, so she gave her consent for the procedure to be performed the following day.

As Jake lay with his head inserted into the giant tube of the MRI chamber, Santos watched the video screen anxiously for any sign of what might be troubling the gelding. Then it appeared: A large mass in the tissues directly
behind his eye.

"It would be very unusual for a tumor---particularly one that size---to be in that location," says Santos. "We figured it had to be a foreign object of some sort, but we wouldn't know for sure until we did surgery to get at it."

By that time Jake had already been under anesthesia for two hours, so it would have been too dangerous to keep him unconscious long enough to perform the surgery just then. Instead, he was taken to a recovery stall and allowed to wake up while Santos discussed the findings with Heistand.

The next day the gelding was again prepped for general anesthesia, this time laid out on his left side on a surgical table. Using the MRI images as a guide, Santos made an incision four centimeters long just behind the outside corner of Jake's right eye and pulled back the tissues below the skin. Deep down in the opening he spotted something dark and solid. Grabbing the object with forceps he pulled it out carefully. Holding it up in the brightly lit surgical suite, Santos finally identified the source of Jake's eye woes---a piece of wood, about two inches long and the diameter of a pencil.

"It was in the soft tissue right behind the eyeball," says Santos. "As it will with any foreign object, the body had encapsulated it and was attempting to push it to the surface and out. It couldn't push it out through the eye, so all we were seeing was the drainage from that effort." Santos cleaned the wound thoroughly and left it to heal without sutures. Jake recovered uneventfully and was sent home with a course of antibiotics the following day.

Round two
But Jake's troubles still weren't over. Heistand was told the drainage from the eye would stop within a few days, so she was concerned when it did not. "It got better, but it never really resolved," she said.

Ten weeks after the first surgery, Jake was back at Hagyard. "They went back in the same area to see what was going on," says Heistand, who watched as Santos pulled yet another two-inch long stick from the tissues directly
behind Jake's eyeball.

"We may have broken a single stick in two during the first procedure, or it may have been a second stick that migrated to that spot after we removed the first one," says Santos. Nevertheless, after exploring the area thoroughly, he was confident that the second stick was the last one. The incision was again left open to heal, and Jake was sent back to Tennessee with yet another round of antibiotics. This time, finally, everything went as expected. The incision healed with no visible scar, and the drainage from the eye stopped within a week.

One last question still loomed: How had Jake managed to get two large pieces of wood lodged behind his eye?

"The eye itself was entirely uninjured," says Santos. "My best guess is that he was scratching on a tree and poked himself with a stick, which then broke and remained lodged in his head."

But that scenario would have meant that there would have been an entry wound where the stick went in, and Heistand, who has owned Jake his entire life, never saw an injury like that: "He never had a cut on his head." She has a different theory: "The pieces of wood match the color of our fence line. It's possible the grass blade he had in his eye was so irritating that he rubbed his face on a fence post and somehow rubbed the wood into his eye. I really don't remember any injury to his head or eye, though. It's really baffling."

Regardless of the cause, the outcome of Jake's case might have been very different without the MRI. "As the discharge worsened, we probably would have ended up removing the eye," Santos says. "But that wouldn't have solved the problem because the wood was in the tissues behind the globe. He still would have had the discharge even after he lost the eye. It may have even eventually led to him being put down."

Instead, Jake's story ends happily, with him safe at home with his herd. "You'd never know he had such an unusual problem," says Heistand. "He's back to being Jake."