Hello I am Robyn Wheeler, Colin Wheeler's wife, I manage a vet clinic here in NH. We see our fair share of allergy problems. We have had some good luck with either Episoothe shampoo or hylte shampoo, there is also a shampoo called Relief that I have heard works well but I have not used it in my clinic, we have put some dogs on benadryl but that does not always work. We also use the Royle Cain foods for dogs with allergies. This food comes in a rabbit, venison or duck formula. If you think the allergy is related to a poultry product or by product stay away from the duck formulation of the food. This food can be pricey a 35# bag roughly costs $70.00. Our lab has had some nail issues which can be related to allergy issues and we have started him on a skin vitamin called 3V Caps the large to giant breed formulation, we hope to see good results with this as well, it contains high levels of the omega 3 fatty acids. If you find that his allergies are related to his diet I would highly recommend that you stay away from all people food. You also may want to consult you regular vet about seeing a animal dermatoligist. Good luck let me know if I can help with anything else. thanks for listening and I hope some of this helps.
p.s - some allergys can be linked to the region you live in. unfortunately some dogs do end up needing allergy testing and need to receive allergy injections for life, if there is no resolution with any of the above. Good Luck
Robyn Wheeler.