Hello all,
I have a 2 year old yorkie male and he has started to grow coarse black hair between his shoulder blades. It is about 3 inches long now. Is this normal?

Toughy is my first yorkie and I am still learning.
Sharstin
Update: I had him groomed yesterday and they initially had no idea why this was happening either. When I went back to pick him up they wanted to know if I had used a spot flea and tick product on him like Frontline. I did this summer twice. They said that is the only thing they could think of (because of the location of hair growth) and they haven't seen it on any of the other dogs they groom. What do you all think?
I pulled up the hair for the picture. It does lie flat normally.