My cat rarely goes outside and doesn't often get fleas, so I've been a bit slack on keeping her up to date with flea treatment.
Last week I found a live flea and dosed her up with frontline, but I noticed she's still scratching a lot, biting the base of her tail etc, so I suspected it hasn't worked. Checked the frontline packet and sadly it's well out of date.
So, my question is, how soon can I retreat her ( with in-date stuff, obvs)? Should I wait the usual month, or could I risk treating her again straight away, since the first lot didn't work.