“He’s just got ‘old horse teeth’ doc!”
That’s usually the response from the horse owner or farm manager when I bring up the subject of an older horse’s diseased incisors. Yes, older horses have changes in the size, shape and orientation of their teeth, but broken incisors, “laid over” teeth, loose front teeth, and gingivitis are not a normal finding in an older horse. In fact, these are signs of a serious, debilitating, painful disorder called “Equine Odontoclastic Tooth Resorption and Hypercementosis (EOTRH).”
I know, it’s an awful name. I can barely spit it out myself and I sound like a pompous know-it-all when I do. Unfortunately, we’re unlikely to give it a newer, catchier name any time soon (gone are the days of naming diseases after fabulous descriptive terminology like “trench mouth,” “pizzle rot,” or “bog spavin”). Regardless of the tongue-twisting name, it’s extremely important that horse owners know the signs of this disease. Allowing horses to suffer for years with this condition is simply unacceptable.
EOTRH is a newly recognized disease; it was only first identified in 2004. Since then, the veterinary profession has become increasingly aware of it. The condition involves proliferation (out-of-control growth) of the outer covering of equine teeth, called cementum (this is the “hypercementosis” part). In addition, many horses also have destruction of the internal structure of the teeth (the “resorption” part). As the disease progresses, the front teeth can become loose and crooked, or break off due to weakness and infection. In addition, the bone of the jaw can become infected.
This condition is obviously painful, and one of the first signs of the disease may be the horse’s refusal to bite a carrot or treat. Other early signs include drooling, decreased appetite, or abnormal behavior at the water trough (rinsing the mouth, dunking the muzzle, etc). Tapping on the teeth may produce a painful response. To diagnose EOTRH, we need to take radiographs (X-rays). Radiographs of affected teeth show bulbous root structures and dark spots inside the teeth, which indicate resorption.
At this point, we don’t really know what causes EOTRH. It’s still very new, so research is ongoing. In 2013, Arizona researchers published a study that offered some insight into risk factors for the disease. Management conditions, endocrine diseases and certain previous dental procedures were identified as some of the possible contributors. Excessive dentistry (categorized as prior treatment by a lay floater [unlicensed, non-veterinarian] or incisor reduction) increased the odds for development of EOTRH by five times*. Horses with a history of periodontal disease were also five times more likely to develop the condition. Horses who were fed alfalfa and did not receive turnout (which is more common in western states than here in the Southeast) were twice as likely to have EOTRH. EOTRH was also more common in horses with Equine Cushing’s and Equine Metabolic Syndrome (insulin resistance). It’s way too early to fully understand how these risk factors actually predispose the horse to developing EOTRH, but new information will surely become available in the coming years.
So what do we do about EOTRH? Unfortunately, there are few treatment options. If the horse is in pain, removal of the affected teeth will restore his comfort. Unfortunately, many horse owners are uncomfortable with the idea of extracting some of the horse’s teeth, especially in cases where all of the incisors are affected. Horse owners seem to have a strong emotional response to the idea of a horse without front teeth, and often feel that the horse is better left with the diseased teeth (and the pain). This attitude is frustrating to veterinarians, since the horse should not be allowed to suffer. It’s important to note that horses without incisors are able to graze and live a normal life, and it’s unfair to allow the animal to be in constant dental pain.
If your horse has any symptoms of EOTRH, have your veterinarian evaluate him for this condition. Also, please be open to removal of diseased teeth! Your old friend has likely earned the right to be comfortable as he ages, so don’t deny him that.
- Lisa Kivett, DVM, MS, DACVIM
Foundation Equine Mobile Medicine and Dentistry, Southern Pines NC
* Please read comment below for more information regarding the statement that lay dentistry increases the odds for EOTRH.