You do NOT want to put them in the washer. A previous answerer stated what happens. STINK, big time. It is best to take them to the dry cleaner. They will either dry clean, or send you to a place that will clean the pillows.
When you have this done, they remove the feathers and throw away the ticking. They clean the feathers, and put them back into new ticking, adding feathers to fill out the pillow.
It's not a cheap process, but then, feather pillows can be pretty expensive.
If you want to fluff your pillows, and make them smell better, spray them with Fabreze and throw them in the dryer with a couple of tennis balls. You will be suprised at the dust that will be on your lint filter when you are done.
56 years of feather pillow use