We have worked with hundreds of sloths over the years, (both wild and human-reared) and they can all inflict serious injuries if scared or irritated. We have seen a sloth bite through a human hand leaving a hole big enough that you could look through.
In addition to their seriously sharp teeth, sloths are astonishingly strong. Due to their specialized muscle structure, their muscles are pound for pound stronger than a human’s. Despite their small size, sloths are 3x stronger than the average person. Meaning that if you are up against an angry sloth who wants to bite you, chances are the sloth will be the winner of that wrestling match.
When they reach independence (at the age of about 18 months), even the most gentle of hand-reared sloths just do not want to be handled any longer.
I don’t think you could kill a horse in an open field without a long distance weapon. It’s a flight animal, if you did any significant damage to it, you’d never come close enough to get it to fight you. Enclosed spaces, that’s a different story (you still lose that, it’s a horse).