[Vinniedoggy]

This could also be environmental allergies. My little guy has severe environmental allergies to several trees, weeds, grasses, and molds. He sees an allergist, underwent formal skin allergy testing (following a food elimination diet which showed that his allergies were not being caused by food). He is currently on allergy shots, Atopica, and Zyrtec. He also gets a completely raw diet with a variety of supplments (including essential fatty acids through salmon oil and flax seed oil). Finally, we do a medicated bath once a week to fend off any bacterial or yeast infections on his skin.

I adopted him when he was probably at his worst allergy wise and he had a lot of the black spots like you describe, mostly under his armpits where he did the majority of his itching. The black spots have lessened with time, although he still has some. Also, he was missing large patches of hair when I got him, a lot of which has grown back quite nicely.

Allergies in these little guys are quite frustrating, as it's hard to pinpoint the exact cause unless you undergo formal skin testing. I would recommend finding an allergist in your area who can provide a definitive diagnosis, because once you know what you're dealing with, you'll better know how to treat the problem.

Good luck!