This is the "spot case" type of demodectic mange that almost always is self-limiting, i.e. the dog recovers whether you treat him or not. Since I've already talked about this at length in previous posts, why bother to bring up this little guy today?
He's got a couple of spots of hair loss, but they really aren't bothering him much. He came in for his puppy booster vaccinations and the owner hadn't really paid much attention to the spots. I found them during the physical exam, asked the owner if there were any scratching or chewing, and and there wasn't.
You ALWAYS need to do skin scrapings when you see pets with skin problems, even when you are "sure" that it couldn't be mange mites (because sometimes it is anyway).
The cool thing is what I found on the skin scraping. In active cases of demodectic mange, you usually find a lot of mites, and in varying life stages: eggs, larvae, nymphs, adults, little family groups, and so forth. In cases that are recovering, you may find only one or two mites, or none at all.
What you usually don't see is what is in this picture. I have performed countless skin scrapings in the last 33 years and have never seen this before. Neither have the parasitologists on Veterinary Information Network. We know that the mites live deep in the hair follicles, but seeing mites within the hair itself is pretty cool.