I’ve come across a couple of cases of Sarcoptes this winter. Both cases were young dogs with intense pruritus – one on his face and the other around the triceps region.
Although both owners were rather sceptical, both dogs responded very rapidly to therapy with imidacloprid/moxidectin (Advocate, Bayer).
In our neck of the woods, I tend to try trial therapies first as we have a high urban fox population, but perform ELISA blood tests for Sarcoptes in dog cases with persistent signs.
I occasionally do skin scrapes but rarely, if ever, find mites!