I even wash competition quilts. Mostly to block them so they hang nice and square but this can be accomplished by not washing and just saturating them with a spray bottle. I find it easier to just toss it in the washer on a gentle cycle. I have 4 cats and 2 big hairy dogs, none are allowed in either my sewing room or my longarm room but I hand sew my bindings and that is always done downstairs while watching TV with DH and all my critters are present. So I wash to remove all pet hair and any allergens. If I hand quilt the quilt, well that has been handled so much it needs a good washing by the time it is done. I wash for all the reasons cited above, to ensure there are no unpleasant surprises like a popped seam or a bleeder (even though I prewash my fabrics first as well), I wash to remove starch or glue if I used it and to remove any dirt that may have gotten on the quilt. Finally I wash to make sure none of my quilting has come out. Even though I make every effort to secure seams well.