I know that some of you use natural defense by Sergeants. I used it last year once in the fall, and I found that is stained the white ruff yellow. I could not wash it out for months. Was it just me? I don't want to have my two walking around with yellow stains at the base of the neck - it's very visible there. Any advice? Right now, I am thinking of using some other natural sprays and shampoos instead.