IMHO, people wash their quilts way to often. Unless you are really abusing a quilt it rarely needs to be washed. Usually a good airing and or the gentle vacuum treatment should be all that is needed for most quilts. Of course the ones littles play with are meant to be abused so that is an exception. When animals are part of the equation you have another situation.
Find out what kind of pressure this quilt is going to live with and you may just want to use something more durable and even that won't last forever if it is overwashed through the years.
peace