Her friend has told her you must wipe a horses bottom after it has poo'd to stop flies bothering it.
I told her that horses have swishy tails to keep the flies away and you must wash and groom them to keep them clean and healthy, just like our dogs, but you not need to wipe their bottoms after toiletting. She doesn't beleive me.
Depends on the horse I'd say! Mine gets a bit of a dirty bum when the grass is lush, but most of my friends' horses don't. The flies don't seem attracted to it (it's under his tail after all) but it does seem to be itchy for him as he tries to scratch it, so I wash his bum if it's dirty when I bring him in.
Hmmm - both right up to a point: Obviously horses don't want their bums wiped everytime time they have a crap. Nevertheless, sometimes they produce a really runny one which goes down back of legs (can also happen if they poo whilst on the move), and a quick wipe with a damp sponge is needed to stay all smart and sparkling. Horses wiping their bums on trees sounds a bit odd - more likely they're scratching general haunches area (i.e. not equivalent to e.g. dogs dragging their arses across the ground).