my has only dog in 5 years so not to bad

Permethrin is a pyrethroid, not an organo phosphate. It is toxic to cats, fish and aquatic animals but safe for most mammals. It can occaionally have neuro-toxic side effects similar to organo phosphates, but is not absorbed through the skin like organo phosphates are (that's why its toxic to cats, all that licking gets it into their stomach). And of course Bayer say for prevention of ticks, no guarentee, it can be rendered less effective by excessive swimming or bathing, they don't want to be having to defend themselves all the time. They don't state what they can't prove. It's not perfect, but I don't know of anything more effective. My dog hasn't had a deer tick bite as long as I remember to use it regularly.

I'm not a fan of the chemical flea and tick products. I like to search for herbal remedies for most things I can help prevent. Here is a little article I bookmarked that lists a few natural alternatives to preventing fleas and ticks. Natural Flea and Tick Repellent I've been following this since last summer and it's been working great. Keep in mind we do go out often to parks and hiking trails. I have noticed an improvement in the overall health of my dog, as well.