Written by: Kentucky Equine Research

Find out which dental issues to watch for in senior horses.

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Pam MacKenzie Photo

Equine teeth erupt continuously from a horse’s gums throughout its life, but the shape and condition of the teeth change as a horse ages. Because of these factors, older horses may have dental problems not usually observed in younger equines.

Here are some facts about dental condition and management in older horses.

  • Horses over the age of 15 begin to lose tooth enamel, and the chewing surface of each tooth becomes narrower as the tooth shape tapers in older horses. Chewing may be less efficient with these smaller, weaker teeth.
  • Narrower teeth lead to wider interdental gaps that allow feed to become impacted between the teeth, resulting in gum inflammation. Discomfort, infection, and sinusitis often result.
  • Incisors and other teeth may become loose in older horses and should be extracted to control pain as the horse eats.
  • Sharp edges, wave mouth [uneven wear of the molars], and other conditions seen in younger horses also occur frequently in older horses. Correction should be focused on bringing as many teeth as possible into functional condition.
  • Equine odontoclastic tooth resorption and hypercementosis (EOTRH, see sidebar) causes pain in the incisors, halitosis, overproduction of saliva, gum inflammation, and changes in behavior. The cause is not known, and extraction of the incisors may be the only effective treatment.
  • If the horse has extensive dental problems or teeth have been extracted, it may be necessary to change the diet by providing soaked feeds, replacing part of the grain with fat, feeding smaller and more frequent meals, and offering some of the forage as a cubed or pelleted product that can be fed after soaking.

What is EOTRH?

EOTRH is a newly-recognized pathology affecting both the incisors and canine teeth of horses typically older than 15 years. EOTRH is characterized by internal and external resorption of dental structure sometimes associated with excessive production of cementum [surface layer of the tooth]. As the disease progresses, the pulp, periodontal ligament, and alveolar bone become inflamed and infected, leading to reduced structural support for the teeth, degradation of gingiva, increased incisor angle, fistula formation, tooth fracture, and pain.

The most common initial sign of incisor pain reported by owners is a reduced ability in grasping apples and carrots. Many horses over time will eventually become completely disinterested in accepting these treats. Other signs of pain associated with EOTRH include sensitivity to bitting, head-shaking, ptyalism [excessive secretion of saliva], resistance to turning during work, shyness about the head, periodic inappetance, weight loss, and decreased use of incisors for grasping and grazing. Some horses become incredibly adept at grasping feed with the lips, sliding it past the incisors and moving it into the mouth through the “bar” region.

Watching how an EOTRH horse eats hay prior to an oral exam is a good way to gauge the animal’s discomfort and stage of disease. An oral exam can be quite challenging, because patients are resistant to manipulation of the lips and pressure on affected teeth. Placement and opening of an oral speculum can elicit possibly dangerous behaviour even under heavy sedation.

Oral exam findings can include enlarged mandibular lymph nodes, decreased incisor angle not appropriate for age, mucogingival fistulas, severe regional inflammation, purulent drainage, calculus [tartar] and feed accumulation, missing teeth, gingival recession, bulbous enlargement of dental structures, tooth mobility, and other issues. Resorptive lesions in older horses can be found under excessive tartar deposition on the canine teeth. Exposing these lesions after removal of tartar will cause discomfort for the horse and the practitioner should be prepared to address the problem either through extraction under primary care or referral to a dental or surgical specialist.

— Source: Cornell University College of Veterinary Medicine