My sister picked up my DD Monday by one arm and dragged her kicking and screaming "I don't want to go inside!" into the house to keep her from getting stung by a bee that kept hovering around her outside. Only moved her maybe 8 feet this way. DD complained that her arm hurt, but nothing "appeared" to be wrong with it. She kept favoring it all week, only using it if she had to use both hands, and would periodically complain it hurt and then later say it was better. But she was still whimpering at night if it got bumped so I finally brought her in to the doctor yesterday because her arm wasn't getting better. Apparently my DS pulled DD's elbow out of whack - or Nursemaids Elbow as we learned from Tricia earlier this year. The doctor bent her arm this way and that to pop it back into position and it appears to be fine now. Thankfully. They took 2 xrays to be sure there was no break and there didn't appear to be any.
It's interesting how an infant was put into a cast and a preschooler just gets it popped back into place and sent on her way.
So the moral of the story is - don't drag uncooperative children by one arm unless the damage cause by not doing so is worse than the potential damage caused by dragging them somewhere. I suspect it was a combination of being picked up by one arm and then fighting to escape that did it. (Of course, being 8 months pregnant makes it hard to pick up said uncooperative 33 lb 3-year-old.)