The cause of EOTRH is unknown at this time. There is a theory that some older horses get the disease from abnormal wear, but this has not been proven. One study was performed to see if affected horses have abnormalities in several different hormone levels, but did not find a correlation. The study did find that mostly geldings are affected.
EOTRH is a painful condition. Signs can include difficulty chewing, decreased appetite especially for grazing, rubbing the incisors, pain with pressure on the teeth, irritability when being ridden, weight loss, fractured or missing teeth, and a bulbous, red, or recessed appearance to the gums. However, many horses are very stoic. This disease has a gradual progression, so many horses have learned to live with the pain, adapt to it, and show no outward signs of pain.