Thank you for this info on Seresto. It is made by Bayer so should be trustworthy.
I read some reviews after seeing your post and it seems most users find it effective. Some say it takes some time to start working, but then it is great. Of course there are a few who report bad side effects, but that is often the case with med products. Look forward to your tests on your dogs

is it possible to remove the collar after it is put on, as I would prefer to take off for bathing. They say you should not wash dogs more than once per month, which would not work here!
Thanks again and hope it works for you.
BTW it is 45$ on Amazon.