Page 756 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

Gastrointestinal system: 4.1 The upper gastrointestinal tr act 731

VetBooks.ir 4.21 4.22

Fig. 4.21 A horse undergoing CT of the head while Fig. 4.22 A CT transverse reconstruction of a horse
under standing sedation. with a fractured mandible involving a mandibular
tooth.

erupted crowns of the cheek teeth. The cassette is generator with the horse advanced on an air-plinth
placed on the side to be imaged. A Butler’s speculum connected to the bed, or a static bed supporting the
is placed in the mouth and the horse’s head is sup- head with advancement of the ring (Figs. 4.21, 4.22).
ported. Lateral 15º ventrolateral projections are used Helical systems taking a slice of 0.5 mm minimum
to image the maxillary cheek teeth and lateral 10–15º are now available. More recently, smaller cone beam
dorsolateral projections are used for the mandibular systems have been used as a lower-cost alternative,
cheek teeth. Horses with a steeply angled occlusal although currently the images they produce are infe-
surface of the caudal mandibular cheek teeth may rior to 16-slice helical systems. CT enables the fine
require multiple views at different angles, to image detail imaging, and three- dimensional reconstruction
all teeth without superimposition. of the structures of the head, that particularly lends
itself to visualising complicated structures such as
CT scanning of the dentition equine dental apices and reserve crowns. In a recent
CT has been performed in standing sedated horses study it was twice as sensitive as radiography for
since the early 2000s and systems either involve a fixed detecting maxillary pulpitis.

DISEASES OF THE TEETH AND ORAL CAVITY

CONDITIONS ASSOCIATED WITH horses up to 4 years of age when the teeth are erupting
ERUPTION OF THE TEETH and the deciduous dentition is replaced by the per-
manent dentition. Anatomical abnormalities that are
Diseases associated with development and eruption a consequence of developmental abnormalities may
of the teeth are most commonly detected in younger also have secondary consequences in older horses.