My elderly dog gets them too, occasionally. Our vet gives him steroids and an anti-itch spray for us to use on him. Once poor Max got one that became infected from all of the scratching he did. He had to wear a Sun Bonnet Sue cone on his head until it all cleared up. I have no idea what causes them, or how I could get them cleared up without the vet's help. But try to keep your dog from scratching them constantly or they'll become badly infected! 8-)