Specific anatomy and radiographic illustration of the digestive tract and transit time of two orally administered contrast media in Inland bearded dragons (Pogona vitticeps)

Abstract

The aim of this study was to describe the specific gross and radiographic anatomy of the digestive tract of inland bearded dragons ( Pogona vitticeps ). Eleven bearded dragon cadavers of both sexes (6 females, 5 males) were dissected to examine, measure, and document the specific gross anatomy of the alimentary canal. Measurements collected from the cadavers included snout-vent length, total length of the alimentary canal, and the lengths of the individual sections of the gastrointestinal tract, including the esophagus, stomach, small intestine, ampulla coli, isthmus coli, rectum, and the distance from the coprodeum to the vent opening. Twenty-two healthy adult bearded dragons (13 females, 9 males) maintained under standardized husbandry conditions underwent a physical examination, blood collection, and whole-body dorsoventral and lateral survey radiographs; these animals were used to provide the radiographic images of the complete digestive tract. For the subsequent contrast passage studies, two different contrast media, barium sulfate (BaSO 4 , Barilux suspension) and an iodinated ionic radiocontrast agent (Sodium meglumine amidotrizoate [SMAT], Gastrografin), were used. Water-diluted Barilux suspension (dose 9 ml/kg) was administered orally to 5 bearded dragons, while Gastrografin (dose 5ml/kg) was administered orally to 21 bearded dragons. Four animals were used for both contrast media studies, but received a break of four weeks in between. Dorsoventral and laterolateral radiographs were collected at 0 (baseline), 15, 30, and 45 minutes and 1, 2, 3, 4, 5, 6, 8, 10, 12, 24, 30, and 36 hours after each contrast medium was administered. Both contrast media were found to illustrate the alimentary tracts in the adult bearded dragons. Transit time was substantially faster with SMAT, and SMAT illustrated the entire gastrointestinal tract within 36 hours; BaSO 4 did not fully illustrate the gastrointestinal tract in 36 hours. These results might serve as a guideline for the interpretation of subsequent contrast studies in this lizard species.

Gross anatomy, histology and blood vessel topography of the alimentary canal of the Inland Bearded Dragon (Pogona vitticeps)

“…The specimens were photographed for documentation purposes. In addition, exact measurements of the sections of the alimentary canal were taken and have been published recently [6].…”

“…observed by radiographic studies [5,6,18]. Intra vitam, in this lizard species, the stomach runs only caudally, at first slightly to the left and then after turning, to the right.…”

“…In another ultrasound study, the gastrointestinal tract could be investigated best when it was empty or filled with liquids, otherwise the signal was blocked by gas [4]. Radiography after administering contrast medium has proved to be safe and informative [5,6], as it not only shows the whole alimentary canal but also proves its patency. The alimentary canal is the part of the digestive tract, which follows the pharynx and terminates with the anus or vent [7,8], and cannot be examined via direct inspection.…”

“…To meet the increased demand for anatomical knowledge about the alimentary canal of the bearded dragon, several studies were published recently [3,5,6,9]. However, the nomenclature used is not uniform; the stated reason for this is the absence of an official nomenclature [9].…”