brookcove
Posted : 2/28/2008 9:36:25 AM
I apologize because I can't "agree to disagree" yet on this point, because I don't think this particular angle has quite been addressed?
Let's use my breed because it's relatively healthy and the problems are very well known because Border Collies are run hard even in companion homes and soundness issues show up fast. Let's talk about CEA, an issue where the inheritance pattern is known and there is a test for it in our breed.
What is more responsible, breeding to lines within the breed that are known to be sound - or doing a cross out to another breed, which may carry genes for eye issues that are currently unknown in the Border Collie (PRA?).
Joint issues. Luxated patellas are practically unknown - I've only heard of them from puppy mill dogs, in fact. Elbow dysplasia is so rare that the breed club finds no need to OFA elbows. There are a couple of suspicious lines in this respect, but good, knowlegeable breeders know about them.
What's better, to continue to breed sound line, to sound line, continuing patterns that are known to produce sound puppies 90% of the time, or to cross out to another breed, which may carry a higher rate of genes for elbow, spine, and knee problems?
Soundness in any line of breeding is produced by careful record keeping and culling. Doesn't matter whether we are talking about crosses or purebreds. The thing about the populations of dogs we call "purebreds" is that the gene pool is more stable and predictable. Adding a new influx into that gene pool doesn't "add healthy genes," it adds everything that dog carries, healthy and harmful alike - and in a random way that means one has to start all over again recording and culling to create a stable, healthy gene pool again.
That's assuming one is breeding for health and not something like a particular shade of a recessive dilute color, or head shape, or coat type.