My two cats have been quite bad with fleas since the warmer weather kicked in (to be expected) and I have treated them with Frontline - once last month and again a few of days ago.

Frontline does not seem to be addressing the problem and they are still itching like mad. Has anyone else experienced this?

I'm wondering whether the dose has recently been diluted or maybe there's a reason why.. I'm not sure whether to take them to the vets and get them a jab instead?