Le Ranch: Quicksand Scene
Episode 8
A young teenage girl who abandoned her black colored horse and ran off and steps into the quicksand bog pit, the black colored horse heard her call. And found her sinking and suggesting her horse to find help till it finds that teenage guy who was looking for that girl a leads him to the way and rescues her out of that pit. She only sank towards her neck.
It's a French\German Cartoon. So I don't know if I can find an English dub if they have it. My apologies. :\