When my dog had fleas (10-12 years ago) we tried everything (except oral stuff cause I didn't even know that existed until recently) collars, shampoos, the drops, flea combs with the whole family working to pick and kill any flea we saw, taking him swimming (no idea if that's an actual thing but we thought the fleas might drown) etc nothing worked. Seriously the only thing that worked was winter. The fleas returned the following summer and once again nothing worked but winter. Never had them again after that.
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