We have had this issue for a long time, tried all the things we've found on forums and online... cytopoint injection, working the 1st few times then didn't help. Shampoos, rubs, probiotics, Greek yogurt, apple cider vinegar. We're going back to the vets to see what the next step is, spoke to our groomer who also has a frenchie and has the same issue but her advice is to live with it and yes we have changed his diet many times, raw, grain free etc. He's fine most of the time seems to be when he's left in the house on his own ( a few hours at most) has anyone managed to eradicate this issue completely and long term. Thanks for reading.