Allergies and laundry costs

I have minor allergies to dust, pets and cleaning chemicals. We have a dog in our apartment. Our blankets right now are a few low quality comforters, but they collect dust and make me itch.

I am thinking about getting a down comforter with duvet to cut the cost of needing to wash all the blankets so often. I've seen some on sale since its been getting warmer. Am I right to assume I will be able to just wash the duvet instead of the entire blanket?