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Equine Health Resource

Equine Odontoclastic Tooth Resorption & Hypercementosis, EOTRH

Synonyms: Hypercementosis

The normal equine tooth erupts (moves out of the socket) throughout the life of the horse. In order for this to happen, the attachment between tooth and bony socket must be repeatedly broken down and re-established, with the tooth fixed in its new position.

In EOTRH, this process of release and reattachment is dysfunctional. Either excessive breakdown of the attachment (resorption) or excessive reattachment (cementum production or hypercementosis) occurs. Cementum is the “grout” that lines the tooth and adheres it within the bony socket.

EOTRH was first defined as a syndrome in 2004. It’s causes are poorly understood but there is some thought that it may be brought on by increasing torsional forces as the teeth meet in an increasingly angular way with age.

EOTRH is a disease of the front teeth, the incisors and the canine teeth. It is a very painful condition and usually causes difficulty eating, resistance to bitting, and sometimes salivation, gum recession, and draining tracts or ulcers on the gums overlying the tooth roots. There is a fine line between what is considered normal aging changes versus EOTRH.

Diagnosis requires clinical exam by a vet with dentistry knowledge. Radiographs are diagnostic for the condition. They show the clubbing of the tooth roots and/or resorption of the root or socket as is visible in the accompanying image.

Treatment involves removal of the affected teeth, starting with the worst ones. Whether teeth are removed depends on radiographic appearance and the degree of pain the horse seems to be experiencing. Removal of affected teeth may prevent “spread” to adjacent teeth.

Prognosis & Relevant Factors

The prognosis is poor and the horse will endure ongoing pain if the teeth are not removed. The prognosis is good once the teeth have been removed, with complete healing and resolution of pain in a few weeks.


  • Are you sure that the diagnosis is EOTRH?
  • At what point should the teeth be removed?
  • Will removal of the teeth now prevent this condition in adjacent teeth?
  • How much pain do you think my horse is experiencing?

    Since we don't completely understand EOTRH, it is difficult to know how to prevent it. There is thought that the excessive angulation of incisors in older horse teeth may predispose to the condition by placing excessive torque on the attachments. Overzealous dentistry with heating and repetitive vibration of the teeth has been postulated to be a factor.

    Other factors that may play a role include insulin resistance, PPID and other hormonal disorders seen in older horses, and the aging process itself.

    Helpful Terms & Topics in HSVGWritten, Reviewed or Shared by Experts in Equine Health

    Helpful Outside ResourcesCredible Equine Health Information on the Internet

    Author: Doug Thal DVM Dipl. ABVP


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