Surgical Removal of Bone Spurs Caused by Bit Damage

If your horse is tossing his head or hanging his tongue out while being ridden, going “behind the vertical,” or bearing into the bit, then bone spurs might be the reason. Bone spurs are inflammations of the membrane of fibrous connective tissue that covers the mandible. They usually occur between the corner incisor and second premolar (interdental space) of the lower jaw. The majority of these are caused by bit damage. However, with a simple surgery performed on the farm with the horse under sedation with local anesthesia, bone spurs can be removed and the horse returned to active work.

In his presentation at the American Association of Equine Practitioner's Convention (AAEP) called, “Surgical Removal of Mandibular Periostitis (Bone Spurs) Caused by Bit Damage,” Thomas Johnson, DVM, a practitioner at Advanced Equine Dentistry in Grass Lake, Mich., discussed the causes and diagnosis of bone spurs, how the surgery is performed, and what is involved during recovery.

Since lower jaw impacted wolf teeth, bone sequestra (separated dead bone), mandibular fracture, foreign body intrusion, and an aberrant tooth bud can also cause the above behaviors, it is best to have a veterinarian examine your horse. Performance horses ridden with a large amount of bit contact are most at risk, said Johnson. This includes dressage horses, gaited horses, Western working horses, Standardbred and Thoroughbred racehorses, gaming horses, and polo ponies. Horses with thin, tall bars instead of thick, round bars are more likely to develop bone spurs. In addition, an inexperienced rider or one with overzealous hands can unknowingly injure the horse’s mouth and cause this problem. He cited work done by Hilary Clayton, BVMS, PhD, a gait analysis specialist at Michigan State University’s Mary Anne McPhail Equine Performance Center, where she showed that bit pressure can range from five to 75 pounds, depending on the rider. W. Robert Cook FRCVS, PhD, professor of surgery emeritus at Tufts University’s School of Veterinary Medicine, recently performed a survey of 65 skulls of horses five years and older in museums.  Seventy-five percent of the skulls exhibited bone spurs of between teeth in the jawbone. Accidents such as a horse stepping on a rein, a horse being tied to itself from the bit, and damage from bitting rigs can also be a culprit. A complete oral exam performed under sedation is essential.  The veterinarian should check for proper dental maintenance of the teeth, including correct rounding of the premolars (bit seats), which might ensure comfort with the bit, according to Johnson.

A veterinarian will talk to the rider about the horse’s history, then he or she will palpate the interdental space. Active bone spurs will have a soft and thickened raised area, generally with soft tissue edema (fluid swelling) and possible erosion to the mucosa (mucous membrane in the mouth). Inactive bone spurs will palpate as bony calluses covered with a thin layer of mucosa, according to Johnson. A drainage tract might also be visible, or the horse might have bad breath. If the horse shows pain during palpation, further diagnostics might be in order. This might include radiographs, scintigraphy, computed tomography, and diagnostic nerve blocks. The veterinarian might also want to view the horse under saddle without a bit.

The treatment is a simple surgery to remove the bone spurs. The veterinarian should leave the incision open to heal, according to Johnson. Sutures can result in a bumpy scar with thickened tissue. If your horse undergoes surgery, you might be asked to flush the incision two times a day with salt water for up to 10 days. If feed enters the incision, an odor might be noticeable. The horse is usually placed on the antibiotic trimethoprim/sulfa for a week.

Healing takes about six to eight weeks. The horse can usually be ridden within three to five days without a bit, and it is very important that the horse not be ridden with a bit for the six- to eight-week recovery period. A bitless bridle, sidepull, or hackamore can be used during this recovery time. “This allows the horse and rider to feel what it is like to communicate without pain,” Johnson said.

The veterinarian will recheck the incision site after the recovery period. If it has healed properly, then the bit can be re-introduced. Out of 81 surgeries he has performed for bone spurs caused by bit damage, 79 horses improved dramatically and two had to have further surgery due to reoccurrence. 

“Most riders feel the horse gradually becomes more comfortable and accustomed to contact over several months,” he said. “Most horses stop pulling at the bit or flipping their head to decrease contact. Horses are visibly more accepting of contact on the bit and will actually reach for the bit rather than elude contact.”

He said that case selection is very important. “One should consider the intended use of the horse, the rider’s ability, and the rider or caretaker’s compliance,” he said. “If the horse is a retired dressage horse now being used as a trail horse, surgery may not be necessary. If the rider is not compliant and does not realize why the damage has occurred, the periostitis may reoccur again soon after surgery. As long as the reason for the damage is eliminated and the damaged tissue removed, the horse will gradually forget about the previous pain.”

Johnson warned that the horse might never be as comfortable with a bit as it could have been. He recommended using a bit with less contact on the bars, such as a French link type of snaffle or a low port or Mullen mouth curb bit. Loosening a curb strap can also prevent vise-like action. He recommended checking the bit to make sure that it is not putting pressure in undesired places.

About the Author

Sarah Evers Conrad

Sarah Evers Conrad has a bachelor’s of arts in journalism and equine science from Western Kentucky University. As a lifelong horse lover and equestrian, Conrad started her career at The Horse: Your Guide to Equine Health Care magazine. She has also worked for the United States Equestrian Federation as the managing editor of Equestrian magazine and director of e-communications and served as content manager/travel writer for a Caribbean travel agency. When she isn’t freelancing, Conrad spends her free time enjoying her family, reading, practicing photography, traveling, crocheting, and being around animals in her Lexington, Kentucky, home.

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