Posted by:   Jan Date:   Sept 6, 2006

Subject: Hybrid Vigour and inherited diseases

Jan the hope is Wed Sep 6, 2006 18:01 152.163.100.138 that by outcrossing to a Poodle, the Goldendoodle has a better chance of being healthier than its Golden Retriever parent. Unfortunately, Golden Retrievers can be prone to cancer (according to my local oncologist Vet) at a higher rate than other dogs. Of course, it may just be that Golden Retriever Owners tend to be people who go the extra step and get the condition diagnosed (and treated), but the condition does seem to be more common in Golden Retrievers. The hope with hybrid vigor, then, is that the genes that cause some Goldens to be susceptable to certain cancers is recessive (requiring two copies, one from each parent, to express the condition), and since Poodles aren't known to have a high incidence of the disease, the offspring of such a cross will not express the same level of susceptability as a purebred Golden Retriever might. Since the breeding of this hybrid is still fairly new, no one knows for certain if the hope will be fulfilled. So far though, I can't say there have been any indications of early onset cancers in Goldendoodles that one might see in the same age population of Golden Retrievers, i.e. so far, so good. Certainly, where diseases are shared in both the Retriever and Poodle populations, or where the disease is a dominant characteristic (one copy of bad genes to express the condition), one cannot expect Hybrid Vigor to have any affect. Hybrid vigor is not a panacea, it is simply a term that means that recessive conditions carried by only one parent will not express themselves in offspring of that parent if that parent is bred to a non-carrier. This should only be considered helpful for those conditions that cannot be "tested" out of the breeding population, not an excuse to continue to breed known sickly dogs. By not "testable", I mean: Late onset diseases, or diseases carried but not expressed by the breeding animal but having the potential to be inherited by the offspring. There are no easy answers.