Feeding Horses with EOTRH

Most horse owners are aware that regular dental care is critical to their horse’s health and wellbeing. What is less known are dental diseases, like Equine Odontoclastic Tooth Resorption and Hypercementosis, which is known as EOTRH. This disease typically affects older horses and can severely impact their ability to eat. It can also result in lasting and permanent damage to a horse’s teeth and even loss of individual teeth. Thankfully, there are treatments available for horse owners. However, horses suffering from EOTRH need to have carefully managed diets.     

What is Equine Odontoclastic Tooth Resorption and Hypercementosis (EOTRH)?

EOTRH is a disease that was first classified in 2008, but has most likely been around for much longer. In essence, EOTRH is a painful disease that primarily impacts the incisors and canine teeth in horses. In rare cases, the molars (cheek teeth) of horses can also be impacted by EOTRH.  

The damage done to a horse’s teeth due to EOTRH can range from mild to severe. Generally, this is a progressive disease affecting horses older than 15 years of age. Yet, there are cases of EOTRH in horses as young as 10 years old. Researchers have identified three patterns of EOTRH, which are:

  • Predominant tooth resorption. This is when the afflicted teeth start to break down at the roots and be reabsorbed, leading to breaking or complete loss of a tooth.
  • Predominant hypercementosis. In response to breakdown of the teeth, the horse’s body responds by producing irregular patterns of cementum (hard outer layer) on the afflicted tooth.
  • Combined tooth resorption and hypercementosis. Both breakdown of teeth at the roots with irregular patterns of cementum.

In the early stages of this disease, horses usually do not show any signs or symptoms. This can be quite frustrating to owners, as you will have no warning until the disease is in its later stages. This underlines why annual or bi-annual dental exams are so critical for your horses. As the disease progresses, more outward clinical signs of EOTRH can include:

  • Loss in body condition (weight)
  • Loss of interest in eating or decreased appetite
  • Feed falling from the mouth
  • Drooling
  • Foul breath
  • Behavioral problems, like shyness with mouth
  • Swelling and redness along gums, with bulging tooth roots
  • Small red dots along gums
  • Receding gumline
  • Loose or broken teeth

Scientists are unsure of the exact cause of EOTRH, but it has been proposed to have an immunological basis. What we do know is that it usually only affects older horses. Data also suggests that geldings may be more susceptible. While all breeds of horses can be affected, EOTRH is seen more commonly in Thoroughbreds and Warmbloods.

If you suspect EOTRH in your horses, it is important that you schedule a veterinary exam as soon as possible. While clinical signs can be a good indicator of EOTRH, radiographs are needed to make a solid diagnosis.

Feeding Horses with EOTRH

With any dental disorders in horses, managing their diets to ensure they receive adequate nutrition can be frustrating. This is why managing a horse’s dental health is so important to their wellbeing.  When it comes to dental diseases, like EOTRH, this can be even more difficult to manage. While a simple teeth float of sharp points or hooks in a horse’s mouth can resolve many issues, EOTRH differs. Here, the only current treatment of severe EOTRH is to remove the afflicted teeth. This can result in the loss of a few or all of the horse’s incisor teeth, which are important in selecting forage. In some circumstances, EOTRH can also impact the molars (cheek teeth).

In the stages of the disease where a horse has pain and discomfort in their teeth, there are steps you can take to help them. Due to the pain in their mouth, affected horses may eat less forage or may even completely ignore or eat little of their feed. The goal of your feeding program should be to ensure your horse still receives their daily nutrients, while working with your veterinarian to diagnose and treat your horse. Things to consider include:

  • For horses having difficulty chewing forage, introducing a complete feed that is greater than 15% crude fiber. Here, the goal is to ensure your horse is receiving enough fiber each day, while also getting all other necessary nutrients. Our article on What Is a Complete Feed and Does Your Horse Need One is worth a review.
  • For horses having difficulty chewing their feed, adding water can help turn it into a mash. This will reduce the incidence of mouth pain in chewing pelleted feed.
  • Ensure the horse maintains good digestive health with pre- and probiotics. Specialty products, like Constant Comfort® Plus, can be used in a mash to help during times of stress. This is important, as stress can be a leading cause of colic in many horses.

Even with the afflicted teeth removed, many horses that suffer from EOTRH go on to live healthy and happy lives. This is why teeth removal is the current treatment of choice. Often, this requires the removal of the horse’s incisors, which are important in grasping and cutting long-stem forage. In some circumstances, an EOTRH horse may also have some of their molars (grinding) teeth removed, if afflicted.

Generally, horses that have some or all of their incisors removed can go on to eat long-stem forage with little difficulty. They learn to grasp and tear with their lips and tongue. However, there are still some considerations for these horses:

  • Pastures that have either been heavily grazed or mowed can be difficult for horses without incisors. They will have difficulty grasping forage. Thus, these horses need pastures with longer forage (i.e., > 6 inches).
  • For those having difficulty either grasping or chewing forage, consider introducing a complete feed.
  • Consider feeding chopped hay or cubes. If having difficulty due to loss of molars, soaked hay or cubes make chewing easier.
  • For horses with significant loss of molars, soft mash of a complete feed would be a wise choice.

Finally, it would be advisable to discuss your feeding plan with a nutritional expert. Since many horses in the later stages of EOTRH usually are underweight or losing body condition, adjustments will be needed to ensure your horse is receiving adequate nutrients in their diet. They can also help suggest feed alternatives for these horses. You can contact our team HERE to receive advice or help anytime you need.

Take Home Message

When it comes to dental care, always ensure your horse’s mouths are examined at least once a year, if not 2-3x per year. If your horse suffers from EOTRH, you will need to evaluate their eating behaviors. Once you can establish what and how your horses are eating, you can slowly adjust your feeding strategies accordingly. Again, this would be a circumstance where speaking with nutritional experts, in addition to your veterinarian, would be warranted to receive specific guidance to your situation.


Gorski, K. et al. 2021. EOTRH syndrome in Polish half-bred horses- Two clinical cases. J. Equine Veterinary Science. 101:103428.

Rahmani, V. et al. 2019. History, clinical findings and outcome of horses with radiographic signs of equine odontoclastic tooth resorption and hypercementosis. Veterinary Record. doi:10.1136/ vetrec-2018-105253.

Article By: Chris Mortensen, Ph.D.
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