Equine Odontoclastic Tooth Resorption and Hypercementosis (EOTRH) 
That's A Mouthful!
X-ray of lower incisors in oral speculum exhibiting EOTRH

EOTRH is a newly recognized dental disease typically affecting horses 15 years or older.  It most commonly affects the teeth in the front of the mouth, the incisors and canine teeth.  The cause of this syndrome is not fully understood, but affected teeth begin to resorb, or dissolve. In an attempt to stabilize the dissolving tooth structures, the horse's body lays down excessive amounts of cementum, the calcified substance on the outside of the tooth.  This gives the tooth a bulbous, irregular appearance and the surrounding tissues become inflamed. As the teeth become more unstable they may shift position, fracture, and become infected. Receding gums and draining tracts may also be present.  It is an extremely painful disorder, especially once lesions become infected.


What are the clinical signs of this disease? 

Draining tract over corner incisor

Owners often report a decreased ability to grasp carrots or apples.  Eventually affected horses may refuse these treats altogether.  Other signs include head shaking, excessive salivation, resistance to turning during work, decreased appetite, head shyness, or weight loss.These horses will often be very uncomfortable if a dental speculum is used for examination and can be resistant to manipulation of the lips and pressure on gums.  In spite of heavy sedation, affected horses may still show signs of discomfort. 



Some risk factors for EOTRH have been identified. 

X-ray of bulbous, irregular incisors in horse with EOTRH
  • Lack of grazing time combined with a diet of alfalfa hay greatly increases chances.
  • Horses with underlying endocrine conditions such as Cushing's disease and Equine Metabolic Syndrome (EMS) were twice as likely to develop EOTRH.
  • The disease is seen more often in thoroughbreds, warmbloods, and Arabians. 
  • Some studies have showed an increase of disease in horses 15 years and older.



Diagnosis of EOTRH is made by compiling a thorough history and performing a complete oral examination with x-rays.  Radiographs allow evaluation of the tooth, tooth roots, and surrounding bone.  Since only a portion of the horse's tooth is visible, x-rays help to reveal what is going on below the gum line.

Draining tract with receding gum line



Currently the only treatment for this painful condition is extraction of the affected teeth.  Extraction of all the incisors and canines may be necessary.  Although the tongue may protrude slightly through the lips after incisor removal, the horses do quite well and learn to graze on soft pasture.  These horses should be maintained on a complete pelleted feed and hay with shortened fiber length (chopped hay, hay stretcher or soaked hay cubes) in order to ensure adequate nutrition.  Owners will often report that their horses seem much happier following extraction.





Regular dental care performed by your veterinarian is the best way to detect EOTRH.  If you notice excess salivation, abnormal chewing of carrots, apples, or hay, or head shaking, please schedule an appointment for a complete oral exam.  Horses diagnosed and treated early will have better quality of life and can avoid needless suffering with extreme tooth pain.