When a middle-aged mare with a mysterious mass in her mouth came under the care of Palm Beach Equine Clinic in Wellington, FL, Dr. Weston Davis pulled out all the stops to find a definitive diagnosis. The oral mass was growing at a rapid rate and was positioned just behind the bottom incisors on the left bar of the horse’s mouth.
A view of the oral mass being examined by Dr. Davis.
First, Dr. Davis turned to the use of PBEC’s state-of-the-art computed tomography (CT) machine to obtain an image of the mass and its exact location within the horse’s mouth. Then, a surgical biopsy was performed and the histopathology, or microscopic examination of the biopsied tissue, revealed the manifestation of an ameloblastic fibroma. An ameloblastic fibroma is a mixed odontogenic (dental) tumor composed of soft tissues.
“Although this tumor type rarely metastasizes, it tends to be locally invasive and aggressive, requiring the complete removal and/or aggressive radiation therapy,” said Dr. Davis, who is a board-certified surgeon at PBEC.
The CT scan revealed a tumor.
A tumor of dental origin is rarely found in humans and is extremely rare in equines, but upon diagnosis, Dr. Davis quickly identified a treatment plan, saying, “In this case, the CT mapping that was performed enabled us to completely remove the tumor via a rostral mandibulectomy with preservation of the mandibular symphysis (the joint between the two halves of the mandible).”
Dr. Davis ready to begin the rostral mandibulectomy.
The horse underwent surgery at PBEC and Dr. Davis removed the tumor along with the rostral (front) mandible, which includes the lower incisor teeth and essentially the entire front portion of the lower jaw of the horse.
A view of the lower lip of the horse after surgery.
A view of the inside of the horse’s mouth at the two-week check.
The obvious question that arises from a rostral mandibulectomy is “how effectively will the horse be able to eat without bottom teeth?” For this patient, however, the answer came quickly and it was nothing short of encouraging. The mare returned to eating just hours after surgery and, at her two-week checkup with Dr. Davis, was back on a normal diet of hay, grain, and – of course – treats.
According to Dr. Davis, the majority of animals that undergo this type of surgery often compensate well and have little trouble eating. For this mare, her only struggle in the future may be the prehension of very short and/or tough pasture.
Two weeks post-surgery and no visible signs of a rostral mandibulectomy.
Also at two weeks post-surgery, Dr. Davis approved the mare for light riding activity with a hackamore. The mare competed in the jumper ranks before surgery and at a four-week checkup, Dr. Davis gave the all-clear and the mare returned to full work. She even made a comeback in the competition ring at Palm Beach International Equestrian Center with very little visual evidence that a mandibulectomy was ever performed.
“This was a rare tumor and a rare surgery, but the horse recovered incredibly well and fast!” said Dr. Davis. “It was an excellent patient outcome. “I gave her the all-clear at four weeks post-surgery and she is already back to winning classes.”
All Photos Courtesy of Dr. Weston Davis