Our mare suffered appalling sweetitch all her life and I lost count of the number of topical remedies we tried, some of which worked until she became allergic to them. We came across this product about five years ago, since when we've gone through summers without a problem. We start feeding as soon as the clocks go forward and carry on until they go back again. You do have to introduce it VERY slowly - it has a powerful taste and smell that comes through the skin to deter biting insects and makes the stable stink because it's passed out in the wee! But it's truly worth it. Would recommend Skratch without any hesitation. It's just a shame it took us so long to find some relief for her.