Lol, I meant like just random breeds of dogs coming back. Haha, not like the test coming back with different types of animals. LOL, there would be something seriously wrong!
LOL I didn't think you meant other species!
I was just a little confused because the specific types of testing I said were valid (verifying parentage and testing for genetic disease) had nothing at all to do with breeds, so there is no way for those tests to "come back" with any mix of breeds. Basically, my point was that so-called breed markers are mostly a bunch of BS at this point, but that genetic testing does have other valid uses.
I was thinking you might have misunderstood what I was saying about the Arabians, where it's nothing about any specific Arabian breed markers, but rather a verification that the horse is in fact the offspring of two registered Arabians. At this point, those registered Arabians may also be DNA-verified offspring of two other Arabians, or they may just be DNA-typed. Basically, when the program was adopted, registered breeding horses had DNA samples taken but they were known to be purebred Arabians because...well, they were known to be purebred Arabians. It has nothing to do with the DNA identifying them as such, just standard record keeping.*
Either that, or that you might have misunderstood the genetic disease thing, but the thing is that most genetic diseases in dogs aren't specific to one breed. So multiple breeds could have the genes for a given disease like hip/elbow dysplasia, degenerative myelopathy, etc. Actually, this is one area where dog breeding seems to diverge from horse breeding (which is where my experience lies, in case you can't tell by my equine examples
), because in horses many genetic diseases are quite breed-specific (for example, SCID in Arabians, HERDA and HYPP in Quarter Horses). In dogs, you see many of the same diseases across several breeds. I'm going to have to look into why that is, because it's interesting and I just realized it (and it's also very possible that I'm missing something here). And while breed-specific genetic diseases might give you a clue about the breeds involved (for example, if a horse has HERDA or HYPP, he's almost certainly got at least some Quarter Horse in him), it can't say for sure what breed(s) the horse comes from. If he's HYPP N/H (in other words, got it from one parent, didn't from the other), all that tells you is that one parent probably had some Quarter Horse in him/her somewhere. It could range to a purebred Quarter Horse whose other parent just came from lines that didn't have HYPP or maybe did but the parent was lucky enough to not inherit it, to a horse with just a bit of Quarter Horse blood but whose QH parent was unlucky enough to inherit HYPP and pass it on to the foal. Either way, you'd get an N/H result. And there are plenty of N/N horses, so the absence of HYPP doesn't prove anything, either.
Anyway, a huge oversimplification, various genetic diseases/inheritances work differently (genetics is very complex), etc. but it hopefully gives an idea of why you can't really identify breeds through DNA testing.
*Incidentally, there was a scandal not too long ago but pre-DNA-testing where a non-Arabian stallion sired a lot of successful and supposedly purebred Arabians because of fraud on the part of the stallion owners and trainers. While the fraud was discovered and all the offspring lost their registration, in theory that could have happened in other instances and not been detected. In that case, the DNA test would not reveal anything, because it would still just show that the foal is the offspring of those 2 parents. If one of those parents had, say, a Saddlebred parent prior to DNA testing, no one would know and there would be no way to prove it. However, DNA testing does help prevent another scandal of that sort, because it would be nearly impossible to fake (basically, you'd have to plan the scandal from the moment you registered the young foal, since DNA samples are required with registration...and with the difficulty of predicting a superstar stallion, it's not really practical), and if it was pulled off, it would be very easy to prove.