The Frontline plus sold by vets only does not work itself into the bloodstream. It does treat the sebaceous glands in the epidermis of the skin (tissue
comprising of glands and follicles).
The Frontline and like-products which are sold over the counter at Wal-Mart, PetSmart and Petco do enter the bloodstream.
Swimming and regular bathing with a non-detergent shampoo will not wash Frontline Plus from the glands/fur.
Our vet and other vets have lost cats and dogs due to flea/tick treatments obtained over the counter because the product(s) have entered the bloodstream
causing irreversible fatal toxicity.
Our local news usually runs this warning each Spring
with vet interviews.
I haven't gotten through to Frontline Corp. Offices yet.
Thanks for the heads-up concerning the bloodstream,
I had never thought to ask. Feel better now! : )
Hope this helps...
gregg