How does flea protection work?

[undeterred]

I am wondering about this now that Ollie is swimming every day. Does it make sense to use the external application on the back of his neck or is that getting washed away the first time he goes in the water after it is applied? I am using this product:

[Muttocracy]

1. I think you're supposed to keep them out of water for a little while

but the oil is supposed to spread through their skin and last for a month or so. Info should be on the packaging or the website (is this one Novartis? will go look...)

Merial - here you go - answer is ~24 hours. If your dog has long or dense fur be sure to part it so you're really applying it on the skin.

I can't find my supply since I moved and my older dog got bitten by a tick last week :cry:

http://frontline.us.merial.com/products/products_faqs.asp#q11