It's coloring, plain and simple. It's not a different breed. Only AmStaffs come in blues. Blue is not a natural color in the APBT line. Blue is a natural color in the Mastiff line.
Good breeders won't breed blues (not blue nose, blues). They breed for good temperament and health. Blues are full of health problems. I have two and they are expensive with their allergies and sensitive stomachs (to the tune of $5,000 a year on a good year). I don't even want to think about what we're going to go through with our female when she gets older as she has been showing weak joints starting at 8 weeks of age. We've got her on supplements, but there is only so much you can do when the bone structure was weak to begin with.
Nosaj: I'm going off what the original breeders of the pure lines have stated - there were no blues in their bloodlines. Their dogs also weren't more than 45-50 pounds. Colby himself has stated that these were crossed with mastiffs to bring over the blue coloring and the size. I'm going to listen to the GOOD breeders over these kennels who are buying from each other.
My blue DNA tested Neo Mastiff and AmStaff. You will find her in ANY of these "kennels" breeding the abominations called Gotti, Razor's Edge - all the dogs who are so far away from what the breed standard originally was that the dogs are barely recognizable. These are also the guys who are breeding for COLOR and not temperament. They don't care about that anymore.
None of the original lines had the size of the blues today nor the coloring. Blue Paul was a mastiff mix, though without the size. That is the only "blue" that I can find in any of the original lines. My grandfather swore up and down in the 30s none of them had blue lines. I believe him, Colby, Heinzl, Boudreaux. I don't believe "greeders" who are making their money off this color - they aren't healthy dogs. Breeding dogs just to get a certain color (which is what they are doing) means leaving good temperament and health in the dust. Many blue pit bulls are showing up with health problems (bad skin is really common) and abnormal, fearful temperaments. I have yet to find a single reputable breeder who breeds blues. But I don't consider "kennels" anything more than mass breeding facilities (puppy mills, essentially). They care about nothing more than the money.
I'm not spreading misinformation. I'm quoting the breeders of the original pure bloodlines.
"As a boy growing up, and listening to multiple conversations between my father and visitors such as Collagan, Heinzl Vose, Donovan, and other dogmen from all over the country..never did the word blue appear. There never was a blue Colby dog in my father's yard, nor mine.To my knowledge there was never a blue colored dog reported in any match or sporting event." - Louis Colby
Blue is an AmStaff coloring, not a ABPT coloring.