I too follow a check and treat regime for my dogs, rather than the usual one that vets suggest i.e. treat all year round, fleas or not!!! (just in case!!!)
However, for the past 4 + years now (this is the 4th summer flea season) I have not had to use any chemical flea treatments on my dogs at all. I can only put that down to the use (4 years ago) of a tiny amount of Cod Liver Oil in their dinners??? (1 x capful between 6 - 8 large Pointer sized meals).
I haven't any proof that this oil is acting as a flea deterrant (maybe fleas don't like the taste of the CLO in the dog's blood or its the odour they don't like - rather like garlic???) and I wonder if anyone else on this list uses CLO regularly and if they have also noticed zero fleas????
My dogs live in a clean environment, but it can be hot and dusty during the days and wet and humid overnight - ideal flea conditions??
My dogs also go to shows and obedience etc. so could be exposed to sources if re-infection when they go out??
I stress that I only use a tiny amount as CLO has a strong taste/odour which fussy dogs are not too keen on???
Please, I would love to hear from anyone who has experienced similar "natural flea control" when using CLO????
Cheers, Charlie