We had our dog for little over 3 years now and the itching started last year and it was really bad, so we took him to the vet but he said he didn't have flees but gave him and antibiotic shot for bacteria he said and worked like magic with 2 days. He completely stopped itching. This year he started itching again and the only thing we changed was he water dispenser from last year. We got the cooler shape one with the plastic base so my son thought about it and threw that away and put a glass plate and the itching decreased a lot. I have no idea why but i am happy that it helped.