Just curious, why?
If surgery is required, barium can seep out of the bowel and into the abdominal cavity. Hard to "clean up" and would be seen on future xrays which could confuse a diagnosis. I'ts been so long since I did those kind of xray studies on humans....I think you can use (something like) Omnipaque. It's clear, can be seen on an xray at the time, soon absorbs, and wouldn't be seen in the future. Same things for humans - avoid barium if surgery is imminent.