To help ensure that your dog is being fed the best possible food check out their current food's quallity score and ingredients on the All About Dog Food website. www.allaboutdogfood.co.uk
If your dog is suffereing from any sensitivity then we ould always recommend looking at their diet first. Often by removing chicken and grain from their diet this can vastly import their constitution.
We've had a number of success stories in our shop with dogs that have an ongoing dietry issue, where veterinary prescribed food has not resolved the issue and simply but switching to a Salmon based Grain Free food the problem has cleared up literally overnight, in some case, and in others taken just a few days.