EASY.....I wash and dry mine all the time.
You need a frontloader but if you don't have a frontloader washing machine just go to the laundrymat and use a machine that is a frontloader and then dry with 2 shoes in the dryer with it
ok Let me explain. The tennis shoes will KICK the fluff back into shape as it drys
if you are BRAVE you can wash and dry in your own home machines but you talke a chance of your washing machine with the twisty thing in the middle ripping your mattress topper and if your dryer is not ex large you have to keep opening the dryer door and re arranging the topper so it will dry correctly. Plus the shoes keep kicking the dryer door open.
I use this method for ALL my feather stuff...Pillows, coats , mattress toppers . It's just those big huge mattress toppers that are sometimes to large for home machines. If it is a single I would probably just chance it and delicate wash at home and then dry with the shoes. Anything bigger I would laundrymat it