
How long have they had it for?
According to
this link regarding sarcoptic mange:
"Mites prefer hairless skin thus leaving the ear flaps, elbows and abdomen at highest risk for the red, scaley itchy skin that characterizes sarcoptic mange.....As the infection progresses, eventually most of the dog's body will be involved. Classically, though, the picture begins on the ears (especially the ear margins), the elbows, and abdomen."
Are they itching much? I was always lead to believe that sarcoptic mange caused intense itching. There is a member here called Anna whose dog was diagnosed with sarcoptic mange through a simple blood test, after a long time of steroids as the itching was originally thought to be allergies. Might be worth getting one of them blood tested? Saying that, if your boys ears have cleared a lot after just one treatment I'd probably continue with the same treatment as it would seem to point to mange possibly being the answer..?