Equine Odontoclastic Tooth Resorption & Hypercementosis (EOTRH)

Equine Odontoclastic Tooth Resorption and Hypercementosis, or EOTRH, is a painful, progressive, dental disease affecting the incisors (and less frequently, the canines) in older horses. As the name suggests, EOTRH is characterized by the gradual resorption of internal and external tooth structure and subsequent build up of cementum on the exterior of the tooth. As the disease progresses, the pulp, alveolar bone, and periodontal ligament that holds the tooth in place within the socket become inflamed and infected, thereby reducing the structural security of the tooth. Severe disease may lead to fracturing of the affected teeth. Excessive production of cementum (hypercementosis), often in a bulbous shape, serves as the body’s natural defense to provide added structure to the diseased tooth. It is the loosening of the diseased teeth that is the source of great pain to the horse.

In early stages of EOTRH, where subtle to no signs may be grossly visible, horse owners may notice their horse is less willing or able to bite a carrot or apple, decreased grazing, periodic inappetance, resistance to the bit, head shyness and weight loss. Diligent oral examination performed at least annually by your veterinarian is the key to early diagnosis of the disease. Because tooth resorption below the gumline is often the first stage of the disease and hidden from plain site, radiographic evaluation of the incisors and canines is paramount in helping your veterinarian determine the extent of the disease and how to best provide treatment for your horse.

EOTRH is most common in horses over the age of 15, who are geldings, particularly of the Thoroughbred and Warmblood breeds. Although the exact cause of EOTRH remains unknown, some studies have suggested that horses with a history of floating performed by lay dentists or a history of aggressive incisor reduction, along with horses with limited access to grazing, horses fed forages that don’t require as much chewing to digest (such as alfalfa), and those with endocrine diseases are at higher risk for developing EOTRH. Once the disease begins, there are currently no successful therapies known to slow down its progression. Treatment involves extraction of all diseased teeth, thereby relieving the associated pain and potentially reducing the spread to adjacent unaffected incisors. After extraction, horses are usually placed on a short-term course of antibiotic and anti-inflammatory medications and fed soft mashes until the extraction sites heal. Horses tend to cope very well without incisors, as they don’t need them for chewing/grinding their food (the premolars and molars do that job)! They quickly learn to grasp hay and grass with their lips and are happy eaters once the painful incisors are removed.

For more information about EOTRH, or to have your horse evaluated for this disease, we recommend scheduling an oral examination with your veterinarian.

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