>im beginning to think my two dogs are getting immune to it. Is this possible?
Well this debate raises its head as regular as the flea life cycle itself!
Anectodatly there are people who say yes, and (sometimes on advice from their vet!) swap to other products Advantage (for example) and report good results - So that's the anecdotal evidence of which you'll find lots, but the science suggests otherwise.. personally I think it's the flea life cycle at work here and not the product swap!! This was cited by Dr.Tim Nuttal Veterinary Dermatologist University Liverpool in the BBC link I've provided below. The science below bears this out and many of the authors have cited that veterinarians should educate pet owners better in the life cycle of the flea to achieve better prevention and not have unrealistic expectations when they have mismanaged prevention!
There have been several Veterinary research papers published, I'm sure there is another even more recent (2011) regarding Fipronil,
one study was published in the February 2009 issue of the Journal of Economic Entomology (Rdl gene polymorphism and sequence analysis and relation to in vivo fipronil susceptibility in strain of the cat flea). This study found no evidence of flea resistance to fipronil.
BBC News Article on 'Super Fleas'I use frontline, never had a problem. There have been instances where I've totally forgotten to use it, good luck or the fact my dog has garlic?..... Well again that's just anecdotal!
Interestingly I've heard recently that Avon skin so soft spray is used by a lot people with good effect.... I would check with people who do as to how you go about this for dog coats ( dilute with water? Etc etc) but I must say I've heard from soooo many people now about it and it originated from the working gundog fraternity ( in fact my Dad! head of media and publications for BASC and writes in the shooting magazines)
:-)