EOTRH Syndrome in Horses

EORTH = Equine Odontoclastic Tooth Resorption and Hypercementosis 

The onset of EOTRH is gradual and most common in horses over 15 years old.

EORTH is a syndrome that results in loss of  tooth material and/or excess tooth material of the incisors and canine teeth of horses.

The other name for this is “Ugly Old Horse Teeth” and you can see why in the photos below.

When the normal process of tooth ligament breakdown that allows for continual eruption gets excessive EOTRH can occur. This causes the tooth roots to disappear, the incisors and canines become loose and shift around. The loose tooth can be extremely painful for the horse.  Some horses will have difficulty eating or even stop eating altogether but most will maintain their weight. The canine teeth many times will have exposed pulp but still only painful on palpation of the tooth but eating feed okay. Extraction of the loose tooth brings complete relief in all cases.


Photo: Courtesy Dr. Ann Pearson

Hypercementosis, roots creating extra bony cement protruding from the gums, can also occur. The affected teeth appear discolored and irregular. This is exaggerated re-attachment of the periodontal ligament as the tooth erupts.  The process becomes embellished by the addition of extra cementum on the tooth surface. The upper incisors will look If this happens and the tooth is non-painful, non-mobile and there is no gingivitis then no further action needs to be taken. In this case, monitoring for gingivitis, pain and/or mobility should be done during regular scheduled dental visits. If any of these occur, then x-rays should be taken.


Sometimes both resorption and hypercementosis are are seen together. Then it is determined whether or not to extract the tooth based on clinical symptoms as many horses are comfortable until the tooth becomes loose and even then most will still eat and maintain weight  but are painful on palpation of the affected tooth. At that point extraction is easy and will relieve the pain.


Photo: Courtesy Dr. Ann Pearson

Recently, researchers in Austria determined that red complex bacteria can be an indicator that a horse will have EOTRH. This may be important for early diagnosis of the periodontal disease if a good testing procedure can be developed. It can also lead to better preventive care. Meanwhile decreasing other risk factors and keeping gingivitis at bay may help prevent the condition from occurring in your horse.

There are many other risk factors for EOTRH including tarter build up and gingivitis, lack of grazing time, a diet of primarily alfalfa hay, and endocrine diseases. EOTRH also seems to appear more in Thoroughbreds,  Warmbloods, and Arabians than other breeds. These breeds tend to be on a high alfalfa diet many times, so perhaps it is not so much about breed predilection but again about diet? The other factor is regular dental care, horses whose mouths are comfortable and whose tongues move freely and are free to wear normally have a lower risk level.


The most common initial sign of incisor pain reported by owners is a reduced ability in grasping apples and carrots. Many horses over time will eventually become completely disinterested in accepting these treats. Some will resist bitting and even speculum placement. Sometimes even under sedation the horse will fight placing the speculum due to pain. Some horses are very stoic and early on will show no outward signs of an issue. Diagnosis needs to include radiographs if there is pain, evidence of a draining tract or loose teeth.

If you think your horse may have signs of EOTRH, or if they are 15 years and over and have not had a dental evaluation within the past year, it is time for the dentist to pay them a visit! Get Your Horse Scheduled Today !