When a horse is limping, it’s an obvious indicator he is in pain. Oral pain, on the other hand, can cause just as much (or more) discomfort but is often invisible.

“There is no advantage to a horse to stop eating, so they find ways to chew around the pain,” said Ian Bishop, DVM, owner of Northern Equine Veterinary Services, in Kirkfield, Ontario. “I’ve been called out to see horses that must have had broken jaws for weeks or months standing out at the round bale eating with everybody else.” Weight loss was the only sign something was amiss.

During regular oral exams, veterinarians often find painful dental diseases no one expected because the horse’s behavior had not changed. “We know that in dogs, you’ll find something important on radiographs about 30% of the time. And it’s about 40% of the time in cats,” Bishop said. “In our study, 20% of patients had signs of disease on a radiograph that were not predicted based on an oral exam.”

Before compiling data on the 248 horses in his study, Bishop estimated that full-mouth radiographs would reveal only one in 10 or one in 20 horses had a dental disease. Instead, full-mouth radiographs revealed one in five horses had an undiagnosed dental issue.

“Sometimes, we found a painful dental disease that would progress into complications if left too long,” he said. “In other cases we found abnormalities that we wanted to monitor because they may lead to the horse requiring surgery in the future. “In older horses, a common unexpected finding was a painful disease called equine odontoclastic tooth resorption and hypercementosis (EOTRH).”

By taking dental radiographs to screen for disease, veterinarians might find issues months or even years before they become externally noticeable, potentially making treatment easier and cheaper, preventing consequences such as secondary infections, and saving the horse from additional time spent in pain.

Bishop recommends taking dental radiographs after oral examination almost any time a horse exhibits signs of oral pain or the veterinarian finds something concerning on an oral exam. He believes the images are invaluable for gathering more information about problems found during oral exams as well as discovering or ruling out a disease that might not be immediately apparent.

“The costs and practical challenges of taking dental radiographs can vary a lot, and whether they become part of a routine dental exam will come down to discussions between individual horse owners and their veterinarians,” he said. “Horse owners and veterinarians may also wish to consider including an oral exam and dental radiographs as part of prepurchase exams.”

Full-mouth radiographs offer a snapshot of the horse’s dental health at a specific point in time. Bishop says the next question research needs to address is how long it makes sense to wait before retaking dental radiographs and how frequently to repeat them over the horse’s lifetime.