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Equine Odontoclastic Tooth Resorption and Hypercementosis



Normal Incisors

normal incisors.jpg

Moderate EOTRH

LINN, ALLI.BRISTOL.6-5-Jun-2018.jpg

Severe EOTRH

Severe EOTRH.jpg

EOTRH is a syndrome we see in mostly older equids (horses, donkeys). Because this is a fairly new area of study, we do not have a complete understanding of what causes this disease and therefore, we are limited in our treatment options. EOTRH is most commonly seen in older horses (15+), but has been reported in some less than 10 years of age. The disease is progressive, meaning it gets worse with time and mainly affects the incisors, canine teeth and the tissues surrounding them.

The name is a mouthful, but it describes how the disease works and what is happening:


Odontoclastic Tooth Resorption means that there are cells eating away the tooth. As stated, we do not know why. This usually occurs in the roots of the front teeth and is visible as holes on x-rays. This part of the syndrome is seen in humans and cats, and is poorly understood in them as well. Human patients indicate that these lesions are very painful – a difficult thing to appreciate in horses as they are so stoic.


Hypercementosis means excessive cementum (a material that normally covers the outside of the tooth). This leads to big lumpy roots of the teeth, often visible as protuberant gums of the incisors. In some horses, this process is occurring without tooth resorption and is not thought to be painful.


Clinical Signs: 

Due to the disease process, clinical findings often include fractured teeth, mobile teeth, protubert (or lumpy) gums, gingivitis, recession of the gums, excessive tooth material visible, oozing pustules, red areas of the gums and excessive tartar. Owners sometimes describe a shift in behavior involving the front of the mouth. You may notice your horse stops biting off hard treats such as carrots or apples, suddenly resists bridling or begins rubbing lips/teeth on walls/stall bars etc.



The clinical findings described above are highly suggestive of EOTRH, but radiographs (x-rays) are needed to diagnose the disease and determine which treatment plan is indicated for each individual.



Because we do not understand why this process occurs, we do not know how to stop or slow the progression of the syndrome. Many things have been tried with no success (antibiotics, anti-inflammatories, immune-suppressants, bone-builders, dental bridges, diet changes etc etc etc). In all three species (humans, cats and horses) the only proven treatment is extraction. Sometimes, depending on the tooth, if the visible crown is amputated, the remaining root can be left behind and does not cause a problem (this approach is successfully taken in many cats, but is very case-specific in horses).



Believe it or not, horses do well without those teeth. They graze and do not require a special diet. However, at rest, many horses allow their tongues to hang out of their mouths. The majority of horses still in work hold the tongue in during work, but it is not a guarantee. Horses that have had teeth with these lesions extracted, often undergo a significant personality shift – owners describe rolling the clock back ten years, suddenly playing/eating/interacting more etc, when they had sworn that the horse was not acting differently or exhibiting signs of pain prior to treatment.

Further Information:

Ask us:, call us: 218-343-3474

Article and Images from Dr. David Klugh

SmartPak EOTRH Article by Dr. Leah Limone

Search the web for EOTRH, there is a wealth of information from other doctors, universities and publications.

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