Denise A. Gorondy, DVM
A: Equine Odontoclastic Tooth Resorption and Hypercementosis, also known as EOTRH, is a syndrome in horses that results in mild to severe changes in the incisor teeth and possibly the canine teeth. The disease process results in the resorption or dissolving of both internal and external dental structures to include the periodontal ligament, the pulp, and the surrounding alveolar bone of the incisor (or canine) teeth. In a healthy mouth, these structures are responsible for anchoring the teeth in place. In the natural disease progression of EOTRH, these supporting structures become inflamed and possibly infected and eventually undergo a slow necrosis or dying off. This process results in loosening of the teeth and severe pain. In an attempt to stabilize the affected teeth, the body produces excessive cementum on the exterior of the tooth. Additionally, the gingiva (gums) degrade, the angle of the incisors change, draining tracts or fistulas form, and the affected teeth may become fractured.
EOTRH is typically diagnosed in horses over 15 years of age and there does appear to be a higher incidence in geldings and in Thoroughbreds and Warmbloods. For owners, one of the most commonly observed initial sign of trouble is the horse’s disinterest or inability to grasp and bite off apples or carrots. Other suggestive signs include a change in acceptance of the bridle, resistance to proper head engagement or carriage during work, head shaking, partial inappetance, weight loss, and decreased time spent grazing. With the gradual progression of the disease, many horses learn to grasp and pull off grass with their lips and slide grass and other types of feed past the incisors with the tongue. Since the incisors are not used in the chewing of feed, affected horses may go with the problem undiagnosed for quiet sometime.
Although there are external signs diagnostic of EOTRH, it is required to take radiographs of the incisors to accurately identify the stage of the disease process affecting each individual tooth. It is possible to have different incisors at varying stages of the disease in a horses’ mouth. In early stages, the disease should be monitored every 12 months with a complete oral exam and radiographs. In more severe cases or cases that seem to be progressing rapidly, more frequent evaluation is recommended. It should be noted that horses suffering from EOTRH will be extremely painful when placed in a standard oral speculum and may react adversely or dangerously even under heavy sedation.
Currently the only effective treatment is removal of the affected teeth. Although this may seem like a dramatic measure, owners of horses with EOTRH that have had their horses’ incisors removed all report how exceptional the horses do following the extraction(s). Because of the gradual progression of the disease, most owners don’t realize the extent to which the pain of the condition has negatively changed their horses behavior and quality of life. Post extraction, these horses quickly adapt and can return to eating normal grain and grazing. Based on current research, there appears to be no difference in recovery between removing affected teeth in a staged fashion versus extraction of all affected teeth in a single procedure. Research suggests that some predisposing factors to the development of EOTRH are lack of adequate grazing time over a horses’ lifetime and overly aggressive dental procedures.
So for Meghan and her friend with the retiring Thoroughbred gelding…He absolutely can live turned out on a green pasture. He should be watched closely to make sure that he maintains his weight and adjusts to pasture living well. Depending on the stage of his EOTRH, he may need to have his affected teeth extracted. If he is in the early stages of the disease, he should be routinely monitored and cared for appropriately.