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Posted:
Wednesday, November 1, 2000
Dental Disease in Geriatric Horses: Part 2
Dr. Michael Lowder, DVM, MS
Univ. of GA School of Veterinary Medicine
Incisor Arcade
The incisor arcade can have several abnormalities, including excessive wearing of teeth, malocclusion, or broken, missing, misshapen or malaligned teeth (Figure 1). The incisor arcades in the geriatric horse are classified as normal, smile, frown, step, and tilt or slant. The incisor arcade should be viewed and inspected from the labial, occlusal and profile views. Excessive wear of the incisor arcade in geriatric horses is usually the result of a behavioral problem (eg, wind sucking or cribbing). With such problems the upper incisors are affected, and usually there are few, if any, abnormalities involving the lower arcade. Management of horses with excessive incisor wear centers on correcting the abnormal behavior. If the abnormal behavior can be controlled and there is sufficient reserve crown, the affected teeth will erupt until normal occlusion occurs again. If there is insufficient reserve crown, the only dental management technique available is to maintain a level table surface on the opposing arcade. This is achieved by periodically floating the incisor arcade to ensure that the occlusal (chewing) surface of the incisors approximates the occlusal surface of the cheek teeth.
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Figure 2 Photo.
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Malpositioned incisor teeth in geriatric horses are the result of trauma (Figure 2) and are usually floated to reduce interference with other teeth within the arcade. It is rare for misplaced teeth to require extraction. In geriatric horses, the incisor teeth may erupt to such a length that a space develops between the teeth within an arcade. In such cases, the space between the teeth should be periodically cleaned out.
Canine Teeth
The canine teeth of geriatric horses will often be excessively long and therefore, will need to be shortened (reduced). The excessive length may allow dental calculi to accumulate easily (Figure 3), cause tongue lacerations, biting problems, fighting injuries, or may injure the veterinarian during the oral exam. Reducing the length of the canine teeth will help safeguard against these conditions.
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Figure 3 Photo.
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Disorders Involving the Cheek Teeth
The three most common abnormalities involving the cheek teeth (premolars and molars) in older horses are wave, step, and smooth mouth. A wave mouth is a condition in which there is a substantial difference in the collective height of several teeth. The wave can often be seen or palpated during an oral exam. Several conditions are associated with the development of a wave mouth, including normal attrition of the first molar or fourth premolar, tooth defects, and fractures of teeth or jaws. Attrition of the first molar leads to a difference in the occlusal (chewing) surface of the cheek arcade, which alters the occlusal forces and mastication. Alterations in the normal masticatory process lead to changes in the wear pattern of adjacent teeth. Consequently, this leads to an alteration in the occlusal forces against the opposing arcade and subsequent changes in the occlusal surface of several teeth. The result is development of a wave mouth. Correction of the wave mouth can be performed by several procedures (floating, dremeling, or cutting) that can best be judged by your veterinarian. The objective is to reduce the height of the wave, thus allowing the concave part of the wave to erupt and close the dead space. In some aged horses there is insufficient reserve crown to erupt.
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Figure 4 Photo.
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A step mouth (Figure 4) occurs when one tooth is higher than the two adjacent teeth. A step mouth also alters the normal mastication process of the horse and should be corrected by reducing the crown of the affected tooth, and the occlusal surface of the adjacent teeth.
Smooth mouth, commonly seen in geriatric horses, is a condition in which the occlusal surface of the teeth is smooth. Consequently, the cheek teeth lack the normal ridges that are used to chew feedstuff. A smooth mouth can be iatrogenically created by floating the occlusal surface of the cheek teeth rather than the points and edges. Some horsemen refer to an aged horse as a "smooth mouth" horse, regardless of the status of its teeth.
Next week I will cover some more common dental problems (eg, hooks), periodontal disease, how teeth are extracted in the horse and some nutritional considerations for the older horse.
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