This has been an issue for me ever since we got chickens. I finally solved it by putting my lined crocs by the back door on a mat. When I head out to the chicken house, I switch shoes. When I come in, I switch back. Occasionally, I forget - and I always regret it. I've had to put so many of my tennis shoes and sandals through the washer/dryer. So I've really been working on making it a habi. Because of immunity issues in our family, I'm obsessive about cleanliness.