About 20 years ago while driving down the interstate, we saw a TT suddenly fishtail so hard that the "box" of the trailer separated from the frame, flopped on its side and slid down the freeway. Traffic came to a sudden stop and the TT's driver ran towards the trailer. I thought perhaps there was somebody inside so I got out to help. Turns out there were two dogs in crates riding back there.
The dogs were fine but I suspect they would have been badly injured if they had just been free to roam back there.