How to design a diet for horses suffering or recovering from this dental condition

Equine odontoclastic tooth resorption and hypercementosis, or EOTRH, can be a mouthful of trouble for horses, particularly those older than 15. Although first described in the veterinary literature in 2008, EOTRH has probably been around for some time. In the past decade, however, as emphasis on equine dental care increased, veterinarians collectively noticed this unique condition.  

The disease’s hallmark is resorption, or breakdown, of the incisor and canine teeth, including the tissue surrounding each tooth and the internal roots. Hypercementosis, or excessive production of cementum, which with enamel forms the tooth’s external surface, can occur simultaneously as the body attempts to stabilize the affected teeth. Other cells respond by creating extra cementum that eventually forces out the tooth and root. In severely affected horses, veterinarians surgically extract all diseased incisors to alleviate pain, infection from periodontal (affecting the gums and structures surrounding the teeth) disease, and ­inflammation.

Because anything affecting a horse’s teeth also ultimately affects his ability to consume food, we’ll discuss best practices for feeding EOTRH horses. For more background on this dental disease, see TheHorse.com/35688.

Dietary Links to EOTRH

Reseachers still don’t know what exactly causes hypercementosis in EOTRH-affected horses. However, factors associated with hypercementosis development in humans include functional stress and inflammation of the tooth root (Grier-Lowe et al., 2015). Age-induced strain on the periodontal ligaments, which anchor the teeth in their sockets, could potentially trigger EOTRH development, but not all horses that develop the disease are old. Other factors, including housing and behaviors such as cribbing, might also play a part.

In 2013 Ann Pearson, MS, DVM, and her colleagues at Reata Equine Veterinary Group, in Tucson, Arizona, pored over 12 years of clinic veterinary records looking for potential EOTRH risk factors. Some of the ones they identified include excessive dentistry needs, periodontal disease, pituitary pars intermedia dysfunction (PPID or equine Cushing’s disease), and equine metabolic syndrome (EMS). Surprisingly, age did not appear to be a factor.

Pearson also found that horses fed primarily alfalfa, which requires less chew time than a grass or mixed forage, with no access to pasture were more likely to develop EOTRH.

“The lack of chewing time and difference in elevation of the head will decrease the amount, time, and path of bathing the teeth and gums with saliva,” she says. Saliva helps remove food particles from the spaces between the teeth that can accumulate over time, leading to gum inflammation and eventually periodontal disease.

EOTRH Affects Consumption

Pain associated with EOTRH drastically affects a horse’s ability and willingness to eat, so the horse might stop eating periodically, lose weight, or avoid using his incisors for grazing or grasping food. The trouble is that EOTRH appears to develop or progress slowly, and the disease could be in its advanced stages before the horse shows outward physical signs.

Some horses in earlier stages of the disease and those with primarily hypercementosis and little to no resorption seem to remain comfortable and show no apparent signs of pain, says Jennifer Rawlinson, DVM, Dipl. AVDC-Equine, assistant professor and head of veterinary dentistry and oral surgery at Colorado State University’s Veterinary Teaching Hospital, in Fort Collins.

During regular dental exams, however, veterinarians might see telltale signs of petechiae (pinpoint red spots) along the gingiva, shifting teeth, or bulging tooth roots, says Pearson.

In a 2015 retrospective study, researchers at the University of Pennsylvania’s New Bolton Center found that although all horses admitted to the clinic for ­EOTRH had advanced periodontal disease, most had a healthy score of between 4 and 6 on the nine-point Henneke body condition scale. Only 27% scored lower than 3 and were considered underweight.

Feeding EOTRH-Affected Horses

It might come as a surprise to know that once cleared by a veterinarian, ­EOTRH horses that have had their ­affected incisors removed can consume diets similar to those of healthy horses. Keep them on a pelleted mash for the first 12 hours after surgery, then introduce a soft diet of soaked hay or soaked hay pellets or cubes with dry pelleted feed. Don’t feed whole grains or mixes that include whole grains to horses that suffered from severe signs of the disease, as the feed particles might get lodged in the resulting crevices, says Pearson.

The veterinarian will provide specific instructions for rinsing the horse’s mouth, particularly the surgical sites. Most horses return to a normal hay and feed ration within two months post-surgery, with six to eight weeks of restricted grazing until the mouth has fully healed from the extraction(s).

Also in the 2015 New Bolton Center study, a follow-up postoperative survey of owners with EOTRH-diagnosed horses revealed that 72% of horses continued eating normally after discharge and their body condition scores increased within three to 18 months after extraction.

“It should be emphasized to the owner, though, that a balanced pelleted ration should be the mainstay of the patient’s diet to ensure adequate nutrition,” says Rawlinson.

Grazing With EOTRH

Some incisorless horses become adept at grazing by grabbing blades of grass with their lips. “Horses missing incisors might have difficulty grazing short plants, so if they are in a paddock that is overgrazed or mowed to a short height, it could be hard for them to grasp and nip the plants off,” says Laurie Lawrence, PhD, professor of equine nutrition at the University of Kentucky, in Lexington.

Although turnout is still important for equine mind and body, do not rely on pasture to be a major nutrient source for incisorless horses. With EOTRH horses that are also missing molars, digestible forms of forage will help provide fiber and ensure proper gut health. You could, for instance, feed a complete pelleted feed that is intended to be fed without forage. Senior versions are available for the hard-keeping older horse demographic. Other options include feeding chopped, cubed, or pelleted forage products. Unless the horse has a history of choke or impaction issues, you should still make hay or pasture readily available.

“For horses without incisors (and also cribbers who have worn the arcade so the incisors don’t meet any more), another option when grass is short is to spread some hay cubes around the paddock so they have to move around to search for them,” says Lawrence. “They’re easy enough to pick up, and as long as the molars work they should be able to crunch them.”

Wrapping It Up

We are still learning why EOTRH affects horses, particularly older ones, but it’s clear early detection is paramount to managing the disease. The best course of action if a horse does develop EOTRH is for the veterinarian to surgically remove the affected incisors. Although horses can still graze, pasture might not provide enough forage to meet daily needs, and dietary management includes providing alternative easy-to-chew and digest forage sources. At follow-up dental checks, make sure your practitioner pays special attention to teeth opposing the removed ones, as they will erupt at a faster rate.