EOTRH Syndrome in Horses

Equine Odontoclastic Tooth Resorption and Hypercementosis, also known as EOTRH, is a syndrome in horses that results in resorptive lesions of the incisors and sometimes canine teeth.  It is usually gradual in onset, though often isn’t diagnosed until quite extensive lesions are present.  Most commonly it is a condition of older horses (15+), though we have seen it in horses as young as 13.

While this syndrome has probably existed for many years, it has only been in recent years that it has been properly identified and named.  Diagnosis is typically made through radiographs of the incisors.  This is the only way to know definitively how many teeth are affected, and how severe the lesions are.  We currently do not know the underlying cause for the syndrome.  Because of this, there is no known treatment at this time to help prevent this from happening.  The treatment for affected teeth is extraction.

As the disease progresses, the roots of the incisors (and sometimes canines) start to resorb, or basically dissolve.  In response to this, some horses develop hypercementosis, which is an ecessive buildup of cementum (calcified tissue) on the roots of one ore more teeth. This process can give the appearance of bulb-like swellings around around the roots of the affected teeth in response to try to stabilize these teeth.  Unfortunately, as the disease progresses these teeth eventually start to loosen and become painful.  As further resorption occurs, some horses may even fracture off weakened teeth.  Many of these teeth become infected as well, as the roots continue to degrade.  This can sometimes present with small red “dots” visible above the gum line of the incisors, or even small pimple-like draining tracts in this same area. 

Many older horses are fairly stoic, and don’t always exhibit obvious outward signs of oral pain until the clinical disease is quite progressed.  As severe changes occur, these horses can start to lose weight and go off feed.  Some horses will also exhibit irritable behaviors when being bridled or ridden.  Our goal is to avoid this from happening.  In our experience, horses that are diagnosed and treated earlier on will have more positive outcomes (avoid pain and loss of weight).  It is also interesting to note that many horses bounce back tenfold after extraction of these teeth, even those that end up having all of their incisors extracted at once.  Where their owner didn’t realize there was a painful component to their disease, the horses become much more bright, happy, and personable after the extractions.

If you have questions regarding your horse, please don’t hesitate to call our office. 

Why are radiographs important?

Radiographs are essential to making a diagnosis, because most of this process occurs below the gumline and can not be seen without proper radiographic evaluation.

Treatment of Affected Teeth:

We have extracted incisors on dozens of horses for this condition over the past several years.  What we have found is that extracting the most affected teeth first does seem to help slow down the progression of the resorption spreading to the other teeth.  Our theory is that by removing the source of inflammation, it allows the adjacent bone and neighboring teeth to “quiet” down, so to speak.  The number of teeth that should be extracted is entirely related to the stage of disease when the diagnosis is made.  If we can make an early diagnosis, there may only be 1-4 teeth affected.  As the disease becomes more progressive, all of the upper and/or lower incisors may be affected.  If all of these teeth are severely affected, there is no good clinical reason to leave any of them in place. 

What to Expect After Your Horse has had Teeth Extracted with this Condition:

The follow up care for horses that have incisors extracted typically includes antibiotics and a soft diet for several weeks.  Most horses are back to happily eating by the next day.  We usually recommend no riding with a bit for 2-4 weeks following the procedure.  After that, they can resume all former activities.  One common question that we get asked is whether or not the horse will be able to graze again after the extractions.  The answer is absolutely yes!  It doesn’t take very long for them to figure out how to rip the grasses off with their lips.  The incisors are actually not used for chewing or grinding the food, this is done by the cheek teeth.