This is how many wildlife rehabbers feed orphaned opossums, myself included. Not only is this used with our Virginina opossums in the U.S., but with many other marsupials and others. I have also used a feeding tube with orphaned squirrels a few times. Injured raptors (birds of prey) are also often fed with a feeding tube. Opossums are "born" after only 12-13 days and navigate to the mother's pouch. They then attach to a nipple, which continuously feeds them (only those lucky enough to get their own nipple survive). Because of this, when they end up with a human feeding them, it is more efficient to feed them with a tube since they really don't know how to suck. A very small tube is inserted through the mouth and into the tummy. Formula is delivered with a syringe attached to the tube. The tube is inserted and removed each feeding. The biggest danger is accidentally inserting the tube into the lungs, which will cause immediate aspiration and death. There are a couple of tests to insure the tube is NOT in the lungs. I have often thought it would be a very good way to feed ferret babies who have to be fed by hand, since they seem to be very difficult to keep alive, but have never had the opportunity to try it. Katharine [Posted in FML 5630]