We have two Cocker Spaniels and one has allergies and the other does not. Our allergy dog was obsessively licking his feet and then he started chewing his rump until the hair was gone or matted and the skin was oozing blood- the vet recommended we switch from the lamb and rice to a limited-ingredient dog food like duck and potato, which we have done. He stopped chewing in three days. For variety I tried the same brand with fish and potato but it has chicken fat added and he was back to chewing again so we are now sticking to the duck and potato religiously. Benadryl did help him and us get some sleep at night too.