[krystenah]

I have 2 dogs and 2 cats. I use advantage on them once a month since its suppose to repel them for up to 4 weeks. It's working on My 2 cats, and 12 lb dog, but on my 6 lb dog.. I applied 1 mnth ago, 2 weeks later she was covered in fleas.. so the vet applied some more.. and now 2 weeks later.. I turned her over to look at her skin cause I do this regularly.. and she was covered. It doesn't even really take 2 weeks for it to stop working.. I see them just days later. I seen at least 20-30 fleas on her earlier. Any ideas on why it isn't working for her?