Page 795 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

770 CHAPTER 4

VetBooks.ir Radiography solution. Barium sulphate mixed into paste with
feed enables voluntary ingestion and swallowing
Both plain and contrast radiographs should be
included in a thorough oesophageal investigation
suspected, care must be taken with potentially irri-
(Figs. 4.97, 4.98). The oesophagus is of soft-tissue to be imaged. If oesophageal wall perforation is
radiodensity and it cannot normally be identified tant or toxic contrast media. Negative contrast is
as a discrete structure on plain films being sur- obtained by inflating the oesophagus via a cuffed
rounded by connective tissue of similar density, NG tube placed in the cranial oesophagus. Such
although contrast against the air-filled trachea images are useful for demonstrating foreign bod-
enables some distinction. If the horse has previously ies, diverticula and mural perforations, which can
had a NG tube passed, or if it has a disorder of the become filled with air.
cranial oesophageal sphincter muscles such as with Normal peristalsis can create the impression of
4 branchial arch syndrome, a gas density shadow irregular luminal folds and strictures on contrast
th
representing air in the lumen can be identified. films and a film taken immediately after injection of
The presence of granular shadows caused by food contrast media via a cuffed tube can avoid such arte-
stationary in the lumen is considered an abnormal facts. It should be noted that if evaluation of swal-
radiographic finding. lowing reflexes is desired, then the study should be
Contrast radiographs are indicated whenever attempted without sedation, since most sedatives,
there is a swallowing defect, or where there are including α-2 agonists, will affect the swallowing
irregularities or masses associated with the oesoph- reflex.
ageal lumen. Dynamic studies involving fluoro-
scopic imaging during swallowing are very useful Ultrasonographic examination of the oesophagus
and can demonstrate the presence of duplication Transcutaneous ultrasonography can be useful in
cysts or diverticula. External compression of the the cervical area to identify mural thickening, extra
lumen by masses, generalised cranial megaoesoph- luminal masses, luminal distension with fluid or
agus, strictures and vascular ring anomalies may be perioesophageal diverticula and oedema. A perfo-
diagnosed on contrast radiographs or on fluoros- rated oesophagus leaks saliva and enzymes into sur-
copy. Contrast radiographs can be achieved using rounding tissues, causing cellulitis and oedema that
gas or barium sulphate, or water-soluble iodinated can be identified ultrasonographically.

4.97 4.98

Fig. 4.97 Plain radiograph of the cranial neck in
a horse presenting with choke. Note the regularly-
shaped foreign body in the cranial oesophagus, Fig. 4.98 Positive contrast oesophagram showing a
which after removal was found to be a piece of wood. partially obstructed lumen.
(Photo courtesy Graham Munroe)