Health & Wellness

Equine Odontoclastic Tooth Resorption – EOTRH

Dr. Michelle Roseburg DVM, McKinlay & Peters Equine Hospital

Equine Odontoclastic Tooth Resorption and Hypercementosis is a mouthful to say as well as a mouthful of problems for some horse patients. Never heard of it? Don’t feel bad, as it was first reported by a veterinarian in 2004 and awareness within our profession has slowly spread since then.

EOTRH is a chronic, progressive syndrome mainly of the incisor and canine teeth of older horses in which parts of the incisor teeth are resorbed (dissolved) by the body. These are the teeth at the front of the horse’s mouth. The tooth resorption process can lead to inflammation and pain, as well as weakening the tooth so it is more prone to fracture or infection. In some horses, the body tries to fix the resorption problem by repairing the roots with excessive amounts of cementum (hypercementosis), leading to bulbous, malformed roots. Horses can suffer from tooth resorption alone, or tooth resorption AND hypercementosis, but hypercementosis does not occur without tooth resorption.

Unfortunately, the disease must often be in very advanced stages before we can suspect it just by looking at the incisors. Signs of advanced disease might include painful, swollen gums, loose or fractured teeth, draining tracts in the gumline from infected tooth roots, or signs of pain. You might be able to tell that a horse has painful incisors by offering them the “carrot test”. This tests whether the horse will readily crunch through a carrot with their incisor teeth. A horse with painful incisors may hold the carrot in their mouth without biting down or suck it towards the back teeth without crunching it with the front teeth. Other signs of pain could include generally lower energy or grumpier mood, decreased appetite, holding the tongue between the front teeth to keep them from clacking together, or frequently holding their front teeth in the water trough without drinking. Trying to catch this problem in earlier stages and to definitively diagnose it requires x-ray evaluation, since many of the resorptive changes in these teeth start below the gumline. X-rays will tell us what negative changes are happening in the teeth and how advanced these changes are. Similar to when we go to the dentist and regularly have survey radiographs, horses older than 15 could benefit from survey x-rays of their incisors to identify potential problems early.

Treatment for affected teeth is extraction. Sometimes multiple or all the incisor teeth need to be pulled. One of the biggest concerns owners typically have is whether their horse will be able to eat without any incisors, and the answer is a resounding, “yes!”. Horses cope shockingly well without their front teeth, as their lips are extremely strong and agile. They quickly adapt to pick up their food in a modified fashion and can even graze by ripping the grass with their lips! One potential side effect of this surgery is that some horses will allow their tongue to hang out of their mouth slightly without the incisors holding it behind the lips, but this varies from horse to horse. Overall, many owners report a significant improvement in attitude and appetite once the affected teeth, which are a source of chronic pain, are removed.

We do not know why some horses are affected by this syndrome and some are not. There are ongoing research projects on the subject, with some theories include immune-mediated inflammation, trauma, bacterial infections, or a mixture of these causes.

If you suspect your horse could be suffering from EOTRH, call to schedule an oral exam with x-rays. We will be happy to help!

Related posts



Vesicular Stomatitis


Biosecurity for Equines