We live pretty far away and only see my niece about once a year. Having my daughter body slammed by a pit bull was unnerving. I never saw that behavior before from a dog, at least not that I can remember.
I’ve seen it every day for the last 43 years.
With 5 or 6 going all at once, sometimes the back yard looks like a huge pinball machine..:)
Maybe by the next time you visit, the dog will have emotionally matured *or* the niece will have properly trained it.
I know some of the things dogs do are unnerving to us but they tend to understand our body language better than we understand theirs.
Bottom line is, if you feel uncomfortable having your child near the dog, then don’t.
It’s your child, your choice and your right.