Dentistry and the Geriatric Horse
Most horse owners are aware that the horse’s adult teeth continue to erupt into the oral cavity as they are worn down. The rate is not constant, but averages about 1/8” per year. The cheek teeth are 2.2 to 3.5 inches long initially so by the time the horse is in the mid 20’s, time is running out.

Aside from the common issues of sharp enamel points, hooks and other findings common to all ages, the most common problem challenging geriatric horses is periodontal disease. The periodontium is all of the supporting tissue surrounding the teeth. Periodontal disease (PD) is defined as inflammation of the gums, periodontal ligament and the alveolus (socket) that all act to hold the tooth firmly in place. When conditions exist to compromise these structures, pain develops, the tooth loosens and ultimately the tooth is lost. Studies have shown that up to 60% of horses over 15 years of age have identifiable PD so this is a problem that must be diagnosed and treated to forestall tooth loss as long as possible.

Other normal physiological evolutions are also in play as time passes. The cheek teeth of the horse are designed to be tightly packed together and essentially act as a single unit. The teeth are generally rectangular shaped when newly formed. As they erupt into the oral cavity, however it becomes apparent that they do taper to a thinner dimension as more of the reserve crown and root are exposed. The result is that the teeth can still be tight
at the occlusal surface but at the gum line spaces are present. These spaces are termed diastema, and can serve to trap feedstuff during normal mastication. The resulting mass is irritating to the tissues and harbors bacteria which can cause infection. Without proper treatment this infection can invade the gingiva, cause a deep pocket, spread to the periodontal ligament and even deeper to the root to invade the pulp chamber resulting in a root abscess. All this while the process is painful and causes sequential loosening of the tooth.

A second major dental issue in the geriatric horse occurs when long standing malocclusions such as waves or steps are left unattended and accelerate wear in the opposing arcade leading to cupping out of the occlusal surface that initiates infection through the pulp cavity and eventual apical abscessation and periodontal disease.

Periodontal disease of the incisor and canine teeth also occurs (see EQUUS “A Mouth Full of Trouble” and article here, Equine Odontoclastic Tooth Resorption and Hypercementosis). Overzealous shortening of canine teeth in the past may have introduced infection through an open pulp cavity leading to festering apical abscessation that causes loosening and pain and the eventual need for extraction of the canine tooth involved.

As with many medical conditions, prevention is better that treatment after the fact. The first step is to maintain a regular dental schedule with your veterinarian. Yearly exams for geriatric horses are recommended. This procedure should be done under sedation with a full mouth speculum and bright light to allow a thorough exam both visually and manually checking for feed pocketing, plaque, loose teeth, abnormal wear patterns and sores in the mouth. Before the exam a current history should be taken to include types of feed, weight maintenance, appetite and other things such as mouth odor or excessive salivation. Since each arcade of teeth act as a unit, any alterations in the unit due to overgrowth, abnormal angulation, excessive wear, or loss of a tooth changes the dynamics of the chewing cycle. Mastication is a carefully orchestrated movement of feed from entry into the mouth, grinding of the feed, mixing with saliva, and movement to the back of the mouth using the tongue and hard palate as propulsive force and guide. Abnormal teeth, sores in the mouth, and painful periodontal disease change all of this. Feed can collect in cheek areas, fail to be chewed properly or become wedged between the teeth.

Treatment of periodontal disease once detected first involves correcting any dental overgrowths, such as enamel points, hooks or ramps. Suspicious areas should be examined with a dental mirror and a periodontal probe. Next trapped feed should be cleaned out with picks and flushing. Larger pockets are sometimes packed with antibiotic preparations. If the tooth is loose, it sometimes can be rehabilitated by correcting existing dental abnormalities and continued antiseptic flushing. If it is too compromised to save, the best course is extraction. In the geriatric horse, extractions are usually accomplished with regional and local anesthesia and elevation and extraction through the mouth. Sometimes the decision is not clear-cut and dental x-rays should be taken to evaluate the condition of the periodontal ligament and the supporting bone. If at all possible, one ties to save the tooth for as long as can be, even if at some later date it requires removal. (See article Dental Extractions in the Horse)

In some cases a diastema may be enlarged to allow feed to more easily pass through without being trapped. These so called “valve diastema” are opened at the occlusal surface so that food trapped down near the gum can move up and out more easily.

Diet changes may also be needed for the geriatric patient. Manufactured senior feeds should be a part of the diet if hay cannot be managed efficiently. Vitamins and minerals should be supplemented as needed. Senior feeds may be soaked for old horses missing significant numbers of teeth.

PPID (Cushing’s disease) is a common malady of older horses and must be managed due to its effect on immune status making the horse more open to chronic infections, including periodontal disease. (See article on PPID)

From Equine Dentistry by Baker and Easley:

“Even if severe dental disease is present it may not be the main contributing factor to weight loss or poor condition”. Just a reminder that a complete health exam should be accomplished on older horses at regular intervals, and a complete blood panel may be indicated to look for anemia, kidney or liver disease, or signs of infection.

All horses wear their teeth to the root if they live long enough. The teeth will become smooth on the occlusal surface because the crown contained enamel and the root does not.”

With these root nubs mastication and digestion is not as effective. Any diseased teeth with periodontal disease that become loosened are painful and the horse avoids chewing on that side, may take much longer to eat, or may soak hay in water to make chewing easier. He may wad hay up around a diseased tooth, or catch masses of hay in diastema or in spaces where teeth have been lost. These “quids” or blobs of wet, partially chewed hay, may be seen on the ground or in the feeder where the horse eats. Most old horses need a change in diet to processed senior feeds and soaked hay cubes. Loose, diseased teeth should be extracted to relieve pain. It would be abusive to leave these teeth in place until they rot out by themselves. The horse would be subjected to prolonged infection as well as pain.

In dogs and finally, now in humans, periodontal infection is recognized as potentially endangering of other organs including the heart and kidneys. Antibiotics are now given routinely following extraction in all species.
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