Tale of two mandibles - The Horse Owner's Resource

Tale of two mandibles

Two incidents on the same farm illustrate how well horses can recover from jaw injuries, even when the causes and treatments are very different.
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The words “broken jaw” summon images of gruesome injuries, uncomfortable treatments and long, uncertain recovery periods. And, when it comes to people, that often isn’t too far off. But for horses, jaw fractures are not necessarily debilitating injuries. In fact, most broken equine jaws are relatively easy to treat, with minimal pain and a good prognosis. 

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This fortunate fact is illustrated by the tale of two jaw fractures that happened to occur, just weeks apart, at A and O Stables in McCoy, Virginia, last year. The farm is owned by Ashley Roberts, DVM, an associate veterinarian at Appalachian Veterinary Services in nearby Riner, Virginia. The horses, their injuries and the treatments they required were about as different as could be, but the end result in both cases was a full recovery.

Buddy: One bad move

Buddy, a big, bay Quarter Horse gelding boarded at Roberts’ farm, is an easygoing horse with a history of good health. He was 18 years old when Roberts found him early one November morning standing over his bucket just looking at his grain. 

“When I see a horse not eating the first thing I think about is a colic,” says Roberts. But Buddy was definitely not colicking; he was bright and alert. “It was like he wanted to eat but he just couldn’t,” she says. “He was showing interest in his grain but he just couldn’t take a bite and chew.”

Taking a closer look at the gelding, Roberts noticed that the left side of his face was swollen. Feeling carefully, she determined that the left underside of his jaw---just a few inches behind his lower lip---was dramatically different in size than the same area on the right. 

“At that time I was pretty sure [his mandible] was broken,” Roberts says. The mandible is the lower bone of the jaw; the bone above is called the maxilla. The lower incisors are anchored to the front portion of the mandible, with the cheek teeth and molars embedded along its length. Behind the teeth, the bone curves upward to form what might colloquially be referred to as the horse’s “cheek.” 

Buddy resisted Roberts’ efforts to examine him. “He was reluctant to let me look in his mouth,” she says. “I gave him some bute and called his owner to tell her what was going on.” She decided to head into her office to retrieve a radiograph machine and a second set of hands to help. 

Roberts returned with Kent Adams, DVM, the founder of Appalachian Veterinary Services, and together the pair took a series of radiographs of Buddy’s swollen, tender jaw. 

The images showed a fracture in the portion of the mandible called the “interdental space,” where there are no teeth, but only on the left side. 

“Usually if [the mandible] breaks in that section, it breaks on both sides,” says Roberts. “So the fact that we could only see one break on his radiographs made it kind of peculiar.”

Seeing no evidence of a flesh wound on Buddy’s jaw, Roberts ruled out a kick from a pasturemate or a similar “battle injury.” Instead, she thought the gelding might have broken his jaw by grabbing onto something---the stall door or even the edge of his water bucket---with his teeth and then pulling back suddenly, perhaps because he was startled. 

“That’s a pretty common injury in young horses. Foals and yearlings, they’ll kind of latch onto something and then spook and jerk back and it just snaps their bottom jaw,” she says. Even though Buddy was older, this seemed the most likely explanation,

Roberts and Adams talked to Buddy’s owner and recommended a referral to the Virginia–Maryland College of Veterinary Medicine hospital in nearby Blacksburg, Virginia, for potential surgery to stabilize the fracture. Buddy’s owner agreed and made arrangements to have him shipped the next day. 

In the meantime, Roberts kept Buddy on bute through the night and soaked his evening grain in water to create a slurry. “By that time, he was eating a little bit,” she says. 

The next morning, Roberts accompanied Buddy and his owner to the uni- versity clinic, where surgery resident Ricky Trahan, DVM, was part of the team managing the case. He reassured them about Buddy’s prospects: “Horses can do surprisingly well with broken jaws,” says Trahan. “If you can stabilize the area, they have the capacity to eat just fine and generally heal very well.” 

Good blood circulation in the area contributes to the speedy healing of jaw fractures, he adds: “The face and mouth and generally most tissues in that area have a good blood supply, which promotes healing and keeps infections at bay. Sure, you can get infected teeth and sinuses, but injuries to the face, like a torn eyelid or a broken jaw, typically heal very well if the blood supply is not compromised.”

A second set of radiographs confirmed that Buddy’s mandible was broken only on the left side, which made a fairly straightforward repair possible. “Because the right side of his jaw was stable, we were able to use that to our advantage,” Trahan says. 

With Buddy standing and sedated, the surgeons anchored a wire to the canine tooth on the right side of the jaw. Then they ran that wire across the front of the mouth---weaving through the front teeth---and attached it to the second premolar on the left side just past the fracture site. “The purpose of the wire is to stabilize the mouth,” explains Trahan. “People with broken jaws often have them wired shut, but that’s not necessary with horses. You can just run wire from one side to the other and they continue to happily eat and drink.”

Sure enough, by evening on the day of the surgery, Buddy had fully recovered from sedation and happily ate some soaked feed. He remained at the veterinary school for three days, mainly so that his food and water intake, as well as his level of discomfort, could be closely monitored. 

When Buddy came home, there was one significant change to his daily routine: “You can’t let a horse graze with a broken jaw,” says Roberts. “If they pull on grass it will stress the area and break the wire. He went on stall rest, essentially, but he could go out in our indoor arena because it doesn’t have any grass.”

To offset the lack of grazing, Roberts made some adjustments to Buddy’s diet. “To get enough fiber into him we started adding alfalfa pellets and beet pulp and rice bran---all soaked as well ---in with his feed. He was getting between a gallon and a half and two gallons of mush per feeding. He could have hay, but it had to be chopped.”

Trahan prescribed the nonsteroidal anti-inflammatory firocoxib for Buddy instead of bute to reduce the risk of ulcers or other side effects. The gelding stayed on that medication for a week, along with a course of antibiotics. Each day, Roberts inspected the wire in Buddy’s mouth and rinsed the area with a mild antiseptic solution. 

Three months after he was injured, Buddy returned to the university clinic for a recheck. By now the wire was gone---having broken and fallen away on its own---but it didn’t matter: Radiographs revealed the site was healing well. 

Back at home, Buddy slowly made the transition from chopped forage and soaked grain to his regular diet, and his owner began riding him, first in a bitless bridle and then with his regular snaffle. 

“He has done great and has never looked back,” Roberts says. “He actually went to his first dressage show recently.”

Star: Just for kicks

Only 15 days after Roberts discovered Buddy’s injury, she found Star, another Quarter Horse gelding boarded on her property, hovering over his full feed bucket one morning without taking a bite. The age of this horse made the sight particularly troubling: He was 33 at the time.

Mentally running through the list of ailments that could stop an older horse from eating, Roberts examined Star. She quickly found the likely source of the problem. 

“He had a large wound, about two inches across, at the corner of his left mandible---where it began to curve upward. At the time, there was no swelling. So I just thought it was a wound and his mouth was sore.”

Roberts gave Star a dose of bute to ward off inflammation and help alleviate pain and left him with his br-eakfast to see if he would eat anything once the medication kicked in. Because of his age and missing teeth, the gelding already was getting a slurry of complete feed twice a day.

“A couple of hours later I went back to check on him and he had eaten everything,” Roberts says, noting that, even so, a thorough examination was necessary. “I called Star’s owner and told him that he had a wound that I needed to look at so I needed to sedate him.”

With Star sedated and the area numbed, Roberts began exploring the wound and discovered it to be much more extensive than it appeared. “I realized the wound was three or four inches deep and it basically traveled straight up to the inside. If you feel a horse’s jaw there, it’s basically skin and bone. There’s not really any muscle there.” Using her fingers and sterile gloves to carefully explore the depths of the wound, Roberts began finding and removing fragments of bone. 

“Some of them were as big as two or three inches across and some of them were tiny---just a few millimeters across,” she says. As best she could surmise, Star had been kicked on the side of the face by a herdmate and the blow had broken his jaw. 

“Surgery wasn’t really an option---even if we did want to wire his jaw, he didn’t have enough teeth left to anchor it to,” says Roberts. “But he didn’t necessarily need that. The best I could tell from palpation was the main part of the mandible was stable. The bone fragments were from a fracture, but not one that was affecting the function or stability of the jaw itself.” 

Roberts continued to pull bone pieces out of Star’s wound until she had about 15 to 20, a pile large enough to nearly fill a shot glass. “I got as many as I possibly could,” she says, “and it was just a wound treatment from there.” 

Star’s advanced age made him more prone to infection, even on his face, so in addition to a standard course of oral antibiotics, Roberts employed a wound-care technique developed for dairy cattle. 

“I used an intra-mammary treatment that is for dairy cows,” Roberts explains. “It’s an antibiotic [cephapirin sodium] we use when they have mastitis, but it comes in a sterile syringe with a long sterile tip applicator that goes in the teat. What I would do is squirt that intra-mammary treatment up into the wound.”

Although unconventional for horses, Roberts was confident in this approach: “If it can go into the mammary gland it’s obviously gentle enough to come into direct contact with the bone.” Roberts treated Star with the cephapirin sodium every other day, and the wound gradually healed. Roberts believes this additional antibiotic treatment helped prevent infection and facilitated Star’s steady recovery.

Just as with Buddy, Star’s healing jaw could not withstand the torque forces of grazing, so the gelding was kept off pasture. But, because of his age, he was already receiving complete pelleted feed that included roughage so his nutritional needs were not a concern.

Throughout his ordeal, Star was a model patient. “Other than right when I found it, he never stopped eating,” says Roberts. “That is really the key to why he did so well. He is known here at the barn as the Energizer Bunny---nothing gets in his way. He’s going to do his daily routine or bust.”

Star’s wound was completely closed about a month later, and the gelding healed without any problems. “I was anticipating him developing a sequestrum, which is a piece of dead bone that migrates to the surface, but he never did. I palpate his mandibles now, because it’s amazing to me, and I can still feel a concave area,” says Roberts. “But he’ll let you mess with it and he’s fine.” 

Two horses, two broken jaws, two full recoveries. These successes were a result of prompt care, dedicated nursing and, says Roberts, the good appetites of the patients. “Horses generally recover from jaw fractures really well, but some have a really hard time,” she says. “I think the key is eating. If a fractured jaw stops a horse from eating, things get very complicated very quickly and the outlook isn’t so good. In both cases, the horses kept eating and I think that made a huge difference. It’s always nice when things turn out this well.” 

This article was originally published the March 2016 issue, Volume #474 of EQUUS magazine