is exposure to mice, rats and hamsters going to mask HCG from tests Hi, I read a post on this website, about a woman who was having pregnancy symptoms but had negative HPT s and 3 negative blood tests. Someone answered and said that if you have had previous exposure to mice, rats, or hamsters their antibodies will be in your system and will mask or interfere with getting a positive test result on the pregnancy tests . I am wondering if this has happened to anyone else? My husband and I had pet mice last year, we got rid of them and went straight to guniea pigs. Which are from the same family as hamsters.