Let us know how you come out on this! That's one big stain but, if the quilt has already been washed and dried, I would expect it to be pretty much a permanent thing by now. Such a cute quilt that I hope you can save it. If the stain doesn't come out, perhaps it can best be rescued by simply removing that bottom row of doggies and put a border on it. At least, the stain doesn't appear to be up into the body of the quilt and mostly there at the bottom.