Equine Odontoclastic Tooth Resorption and Hypercementosis (EOTRH)

August 4, 2021

By Laura Waitt D.V.M., DACVIM

“Equine Odontoclastic Tooth Resorption and Hypercementosis (EOTRH)” is possibly the most intimidating phrase that your veterinarian could throw at you while performing an oral examination on your beloved horse. Equine owners have become comfortable with things named after people like ‘Cushing’s disease’ or getting a ‘Coggins’ test. They are less comfortable with Pituitary Pars Intermedia Dysfunction (Cushing’s) and an Equine Infectious Anemia (Coggins) test. When you break it down, the name EOTRH just describes what is happening to your horse’s teeth physiologically. It currently does not have a layman’s name.

  • Odontoclastic means the alveolar (bone that holds the tooth in place) is being resorbed by the body.
  • Hypercementosis is the term for inappropriate thickening of the hard substance that makes up teeth (cementum).

Typically, EOTRH affects the incisors and canines and is slowly progressive. It has only been reported in the past 20 years and the trigger that starts the process is currently unknown. Theories include endocrine causes like Cushing’s disease, vitamin and mineral imbalances, horses living longer, food allergies, or an autoimmune disease. There are supplements available on the market that suggest they may help treat EOTRH, but there is no evidence that this is true.

EOTRH is an insidious disease that begins well before owners and veterinarians first start to recognize its signs. It is typically diagnosed on a routine veterinary dental exam when it is well advanced and is mostly identified in older horses (age 15+ years). Intraoral radiography (see above image) helps to identify potential dental problems via x-ray image much earlier than would be possible with standard visual examination of the teeth and gums. Often radiographic changes show more severity than would be expected by an examination of the teeth and gums.

The disease process begins as the alveolar bone loses strength and starts being resorbed while an infiltrate of inflammatory cells destroys the periodontal ligament (soft tissue that holds the tooth in place). Then the tooth itself starts to enlarge with extra cementum. Because horses are quite stoic and adapt to this chronic pain, initially the signs can be very subtle. Chronically affected horses can have weight loss, lack of appetite, attitude changes, hypersalivation, head shaking, discomfort in the bridle, and general ‘grumpiness.’

Mild cases of EOTRH may simply be monitored with regular oral exams and radiographs as needed to follow the progression of the disease. However, staged or complete tooth extraction is recommended for horses that are showing signs of discomfort. Horses tolerate extractions very well. It is typically not until the pain is gone that the owner realizes how much it was affecting the horse. If you suspect EOTRH in your horse, contact your veterinarian to perform an examination and potentially perform radiographs for a more complete diagnosis.

The information contained in this article is not intended to be a substitute for professional medical advice, diagnosis, care, or treatment. Always consult your veterinarian for any questions regarding any possible medical condition.

Laura Waitt, D.V.M., DACVIM, is board-certified in large animal internal medicine and serves as Clinical Assistant Professor at the Equine and Bovine Center at Midwestern University’s College of Veterinary Medicine in Glendale, Arizona. Dr. Waitt supervises veterinary students in their last two years of clinical training at the Equine and Bovine Center, part of the Midwestern University Animal Health Institute in Glendale, Arizona. The Equine and Bovine Center provides veterinary diagnostic and treatment services both at the Glendale clinic and on location, utilizing the latest technology to provide high-quality care at affordable prices. For more information, call 623-806-7375 or visit: www.mwuanimalhealth.com

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