pixie374 "Woof, I understand all that, but I'm not sure it's that straightforward. "Carefully bred" for purebreeds, is generally because they have to be- mostly because a lot of them at some point or other have been so interbred, that certain problems become wellknown to certain breeds. And of course, they can pass it on with crossbreeding. But we have caused these with deliberate breeding and now have to correct it.
Realistically, if dogs were always left as mongrels, the gene pool would have been far more mixed and healthier from the start. It's humans that have made certain breeds unhealthy."
well.......kind of. Regardless of what type of dog they are, if they carry inheritable diseases they will pass on the disease...and if the dog they are bred to has inheritable diseases then those will get passed on too.
A case in point that I know about is hip displasia in weimaraners. The average scores now in carefully bred animals are much better than they were 30 years ago because many breeders cared enough to choose carefully when they bred their bytches and refused to allow the dogs to be used by any old person.
If dogs were left to run in groups and choose their own partners, then the fittest would survive and those who weren't healthy enough wouldn't survive tout court.
However we know this doesn't happen with pet dogs. The pairings are chosen by humans or are from accidents which, without health testing is a lottery no matter what the dog.
You won't get any argument from me about people breeding for looks over health and temperament. Its bad if its done in the show world, its bad if its done in the pet world.
but if you believe that a dog who is a mongrel or a crossbreed is healthier or better in temperament simply because they are hybrids, crossbreeds or mongrels then you are wrong. Some crossbreeds can be a very risky proposition, for instance if you mix a guarding and a herding breed without having a clear idea what you are doing.