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EQUINE VETERINARY EDUCATION / AE / MAY 2015
Fig 3: Computed tomography images, obtained after injection of intravenous contrast material, in a lung window. a) Transverse image at the level of the seventh thoracic vertebra showing the dilated proximal oesophagus (white arrow), located to the right of the aorta (black arrow) and dorsal to the main stem bronchi. The feeding tube is demonstrated in the lumen of the oesophagus. b) Transverse image at the level of eighth thoracic vertebra (2.5 cm caudal to image 3a). The aorta (black arrow) passes to the left of the stricture site in the oesophagus (white arrow), in the normal anatomic position. The feeding tube occupies the entire lumen of the oesophagus at this level. Alveolar infiltrates are noted in the left dorsal lung field. c) Dorsal plane reconstructed image of the thorax through the oesophageal plane. The aorta courses to the left of the midline, in the normal anatomic position (black arrow). An abrupt reduction in the oesophageal lumen diameter is noted at the stricture site (white arrows). The feeding tube is demonstrated in the lumen of the oesophagus.
2 ml/kg bwt of contrast material were injected into the saphenous vein (iohexol 300 g/l, Omnipaque 3003) in order to look for vascular ring anomalies. The feeding tube was demonstrated in the oesophagus, which was located to the left of the trachea and coursed dorsally over the tracheal bifurcation, in the normal anatomical location (Fig 3). The cranial thoracic oesophagus was moderately dilated and gas filled with the distention ending abruptly at the level of the eighth intercostal space. Caudal to this point the oesophageal lumen was collapsed and empty. This finding was consistent with an oesophageal stricture or stenosis. The thoracic vasculature appeared to be in the normal anatomic location. No vascular ring anomalies or other causes of external compression of the oesophagus were observed. Alveolar infiltrates were evident in the caudodorsal lung field, which were probably due to the dorsal recumbency. A milder alveolo-interstial pattern was observed in the caudal left lung and represented the convalescing pneumonia. The recovery
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from the general anaesthesia was long and there was worsening of the abnormal lung sounds on the first day after the procedure, which indicated some clinical deterioration in the aspiration pneumonia. Since there was no evidence of an obvious anatomical
structure causing external pressure on the oesophagus, a dysfunction such a muscular spasm or focal fibrosis were suspected as causes for the stricture and a second attempt to dilate the oesophagus with the balloon was undertaken on the following day. Prior to the procedure, the filly was allowed to nurse from the mare for several seconds and immediately milk was seen flowing from her nostrils, with no apparent clinical improvement. Again, general anaesthesia was avoided due to the pneumonia; however, heavier sedation was used this time (diazepam 0.2 mg/kg bwt, Assival9 and butorphenol 0.04 mg/kg bwt, Morphasol11, i.v.) and flunixin meglumine was used for analgesia (1 mg/kg bwt, i.v., Flunixin Injection12). On endoscopy, the oesophagus was filled with milk and the
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