I used to tube feed puppies when necessary. Sometimes the tube isn't in the right place and they would get aspiration pneumonia. It's easy to get complacent when you do it often. Not to mention having " the blind staggers "when feeding a litter every 3 hrs., around the clock, for the first 10 days.
I had two instances where before I could withdraw the tube the puppy was wracked with convulsions - obviously misplaced tube. I was just sick about it. They never indicated any problem when I first inserted tube. I would have expected discomfort or coughing but they took it readily .
Would imagine the same could(would) happen with chickens. I retired from tube feeding for that reason. At least I did succeed on many occasions - much better than my track record with eye droppers.