Hi,
I cleaned two recently, don't use any nasty detergents or washing powder.
Give a good vac.
I put mine in a bath of warm water and a "wool Safe" carpet cleaning product and manually agitated, then hung them outside and hosed them down thoroughly.
Drying times are 3-4 days, best left hung and occasionally turned. Then brush with a metal pronged comb to fluff back up.
Results are superb, one of mine had been under a dinning room table! So you can imagine how dirty it was!.
Rgds. Tony.