Dear Cindy (Claire is her Cavalier),
My frustration was not aimed at you; I know that you are new. And I’m afraid that my “ad nauseam” comment was somewhat misdirected so I apologize for that; it’s more appropriate elsewhere.
My frustration is that often there is information given on internet boards/groups that is either partially correct, poorly thought out or stated, or simplistic/naive, and then people run with these "facts" to reach conclusions that just aren't accurate rather than carefully deliberating all aspects of the topic. Just because someone (and I include myself, Rod and everyone) posts information, don't automatically assume it is correct without independently checking the facts, considering all aspects, and reading critically.
The initial posting of the Dalmation article was interesting, just as the Boxer information (and giving links is always helpful for people who want to read more deeply about a subject). But Rod pointed out the important difference between the Dalmation problem (single gene that is known causing problem, a single outcross from many years back, breeding results closely analyzed over long period of time, etc.) and the Cavalier problem (multiple unknown genes responsible, two major health problems, more outcrosses necessary than just one, etc.) so this then became sort of an "apples and oranges" comparison. This is why I said that the entire premise is faulty because you can't make a comparison of these two breeds' problem/s. The single example of a CM clear Cavalier descendant from a long ago crossbreeding may be of interest but it has no statistical relevance at all to the topic.
I read something recently in one of the groups (and I can't remember which one, but I think it was the yahoo SM group and I think that Laura Lang wrote it) that discussed the hybrid vigor theory. A crossbred dog with two purebred parents is far from the old "Heinz 57" mutts that aren't very common these days. Hybrid vigor would be more applicable to the Heinz 57 dogs (crosses with many, many different breeds in their genetic makeup) than to the "new" designer crossbreeds (reputed to be more healthy) that are popular these days. I think that this addresses Alisha's point a little bit - hybrid vigor is real but it is not obtained by crossing two breeds (generally with poor quality representatives of the breed as parents). Dave's "car crash" comments are applicable here also.
We have discussed outcrossing to another breed previously (but new members wouldn't necessarily know that) including several discussions about the person who has launched the Cavalier "Recreation" Project seeking to cross Cockers and Paps. (She has a website up about it - you can google and read more.) We do have a good search function here, so I often will search to find previous discussion about a specific topic if I want to remember who said what.
The practical application, though, to this discussion is that if an outcross to another breed is thought to be a good idea, it would have to be a collaboration between dedicated breeders (not pet owners) and researchers to design a breeding model/protocol, select the outcross breed to be used, determine how to match up the breeding pairs, measure the results, etc., etc. I'd much prefer to see breeders and researchers working together to use the tools we have and develop more tools to use to breed away from early-onset MVD and SM with the Cavaliers that we now have. (And PLEASE don't give me those statistics on MVD and SM yet again. I understand them.) This IS possible. If breeders and researchers can't even now do that, why would we think they can tackle the even more difficult (and longer time to a good outcome) outcross question????
It's fine for pet owners (or anyone) to sit around and brainstorm ideas, and part of brainstorming is throwing out ideas no matter how crazy they sound at first. But good conclusions are reached by careful consideration of all aspects of the ideas and checking facts – in other words, by critical thinking. I still believe that the things that pet owners can do include supporting the good breeders, educating themselves and other prospective Cavalier buyers, and “voting with their wallets” by only obtaining puppies from good breeders.
Pat