In this case, the partial (the colon was not completely distended) iohexol enema using fluoroscopy determined the location
of the obstruction and identified it as a ileocolonic junction stricture. Contrast studies, usually upper GI studies using
barium, have been used extensively to diagnose GI disease in reptiles.3,4 An iohexol enema was more advantageous in this patient than the upper GI study because the stricture completely occluded
the lumen of the bowel, making it impossible to evaluate the colon using contrast medium delivered orally to the lesion. Although
they were performed in conjunction with fluoroscopy in this case, plain radiographs can also be used for upper GI or enema
contrast studies in reptiles.
There are several other instances in which an iohexol enema would be more advantageous than a barium upper GI study. For example,
if a GI perforation was suspected, then barium would be contraindicated as it can cause life-threatening peritonitis.9 However, iohexol is water-soluble and much less irritating to the peritoneum, making it safer to use if a perforation is
suspected.10 Also, if the case requires rapid diagnosis, a barium upper GI study would be inappropriate because the GI transit time of
most reptiles is about 30 hours.3,11 A thorough barium contrast study that evaluates the entire GI tract takes several days of imaging, whereas a contrast enema,
while only useful for the lower GI tract, can diagnose a lesion in just a few minutes.
Contrast radiographic procedures have frequently been replaced by endoscopy for the diagnosis of intestinal disease in domestic
animals, but this technique is difficult in smaller reptile patients. Ultrasonography is often used to diagnose disease in
the upper GI tract of mammals but less so for the colon because of acoustic shadowing of gas in the lumen.12
Determining the exact location of a GI lesion is of great importance when planning a surgery and in determining the prognosis.
No difference in prognosis for large bowel surgery compared with small bowel surgery has been shown in dogs and cats. However,
surgeries involving resection and anastamosis of the large bowel usually require a longer surgical time and longer hospitalization
after surgery, which have been shown to correspond to increased morbidity.13 Thorough imaging is also important to help determine if there is more than one lesion that will require surgery, as animals
undergoing more than one intestinal procedure have increased mortality.13
An iohexol enema is a valid and relatively simple procedure that is underused in diagnosing intestinal lesions in reptiles
and is very useful when combined with an upper GI study. This imaging technique is easily applied in a private practice setting,
where access to the more expensive advanced imaging techniques such as magnetic resonance imaging or computed tomography is
limited. The use of contrast enemas should be encouraged when obtaining radiographs of reptiles with GI disease.
The authors thank Drs. Matt Sherwood and Marian Benitez (Department of Clinical Sciences, College of Veterinary Medicine,
Kansas State University) for performing the surgery and Dr. Jamie Henningson (Department of Diagnostic Medicine & Pathobiology,
College of Veterinary Medicine, Kansas State University) for providing the histopathology report.
Katie W. Delk, DVM, David S. Biller, DVM, DACVR, James W. Carpenter, DVM, DACZM, Department of Clinical Sciences, College
of Veterinary Medicine, Kansas State University, Manhattan, KS 66506.