What could this be & how do I treat it. 14 week "Blue" Pit Bull Terrier has what looks like Dog Acne.?

I still have a litter of 14 week old pups "Blue" Pit Bull Terriers. Of the 5, four of them have what looks like Dog Acne, small hard bumps under the fur. Also a couple have "tiny" spots where it appears there is not fur. There is no redness or any discolor & it doesn't seem to be bothering the pups, nothing they are scraching at. They haven't had any type of examination, but otherwise look & act like very healthy pups. I have both parents, my Male has never had any issues like this, but my female, who just turned 1yr. in August also seems to have some of the same types of conditions, mostly "tiny" spots where there is no fur. Someone once mentioned as far as "Blue" Pit Bull Terriers go, that a "Grayline" Bloodline are known for poor pigment inperfections?? Any advise would be "MUCH" appreciated!! Thank You!!