Ok, I hope this conversation doesn't stir up too much trouble. lol

I've seen several times where people talk about crossing the Belgian breeds. (Malinois X Dutch Shepherds) I've also heard of doing this with GSDs to these breeds as well.

My question is why are mixed breeds considered so healthy by the general public? Is this just an old wives tale? I've heard some people say this is totally false. I’ve heard a solid genetic breeding with proper selection will produce the same.
(This is what I've heard, on both topics. I’m sure others have heard this too.)
What does the board make of all this?

 Quote:

My question is why are mixed breeds considered so healthy by the general public

I would suggest that it might be more a case of purebreds being considered unhealthy.

The public reads about or experiences so many problems with various breeds: HD in large boned breeds, eye problems in bug-eyed toys, breathing problems in squashed-nose breeds, spinal problems in Dobes, blindness in Dalmations, etc, etc, etc.
And a lot ARE a result of breeding for specific traits while ignoring other, detrimental ones.

A mutt may also not be watched as closely; ie, stuck in the back yard or chained to a dog house, a lot of health problems are simply overlooked or ignored. After all, we didn't "pay" for Patches, you know...(not to ignore the leagues of people who take very good care of their mutts, but just to make a point!)

And lastly, there may be an "under-dog" syndrome that sympathizes with the mutt, over the usually expensive pure bred dog.

As always, just IMHO... <img src="/ubbthreads/images/graemlins/smile.gif" alt="" />
___________________
"A positive attitude may not solve all of your problems, but it will annoy enough people to make it worth the effort" - Herm Albright

I'll ramble on for a bit.

The definition of a purebred is a limited gene pool known for specific traits (or at least that's the one I'll use). The larger the breeding gene pool, the easier it is to pick an individual where you will not double up on recessives. Not only is the gene pool larger for cross breds, but other breeds commonly have different genetic problems.

I'll use HD as an example.

There are 4 breeds: A, B, C, D
For ease of argument, they all have N dogs registered.
These breeds have different rates of HD.
A: 50% (N/2 affected)
B: 25% (N/4 affected)
C: 12.5% (N/8 affected)
D: 6.25% (N/16 affected)

You have a female of each breed and you want purebred pups, the number of available mates is:
A: N/4 25%
B: 3N/8 37.5%
C: 7N/16 43.75%
D: 15N/32 46.875%

You don't care about the pups being purebred anymore, so you have the males of all four breeds available. That's:
8N/32 + 12N/32 + 14N/32 + 15N/32 = 49N/32 153.125%

That's an increase of:
A: 41N/32
B: 37N/32
C: 35N/32
D: 34N/32

Compared to the per breed avilability, you now have access to:
A: 6.125 times the # of males aviailable otherwise
B: 4.08 " "
C: 3.5 " "
D: 3.26 " "

So cross breeding is clearly beneficial to populations that are severely affected with HD, but the larger the unaffected population within the breed, the less benefit compared to "purebreeding" (although there still is benefit).

Feel free to check my numbers. This would have been better explained with a trait that wasn't polygenic, but I'm too lazy to go change everything now <img src="/ubbthreads/images/graemlins/smile.gif" alt="" /> .

Anybody? Am I that confusing and sleep deprived?

Lauren,
That post is so hard to understand I gave up as soon as I saw the first There are 4 breeds: A, B, C, D Line.. lol

I think the question was

"My question is why are mixed breeds considered so healthy by the general public? Is this just an old wives tale?"

My answer: It's the same, mixed breeds are just as prone to health problems as pure breed dogs. In fact I would bet that mixed breeds are more prone to health problems due to neglect in selective breeding, and "care" recieved at home. When is the last time you saw a fat, out of shape, working dog? How many fat out of shape mixed breed pets do you see at the park?

Yes! <img src="/ubbthreads/images/graemlins/laugh.gif" alt="" /> But not to worry. <img src="/ubbthreads/images/graemlins/smile.gif" alt="" />

 Quote:

Originally posted by Lauren:
Anybody? Am I that confusing and sleep deprived?

Nah......just apparently a lot smarter than most of us.LOL <img src="/ubbthreads/images/graemlins/laugh.gif" alt="" />

 Quote:

Originally posted by Ellen:
Yes! <img src="/ubbthreads/images/graemlins/laugh.gif" alt="" /> But not to worry. <img src="/ubbthreads/images/graemlins/smile.gif" alt="" />

That was in reply to Lauren's question, not Lonnie's. Lonnie, I may be an old wife, but I can't tell if it's a tale. <img src="/ubbthreads/images/graemlins/wink.gif" alt="" />

The condensed version:
Even when there are a lot of registered dogs, if a large % of the population is unbreedable due to health problems the gene pool could lack the diversity needed to maintain a healthy long term breeding plan. This is especially true when you are breeding for other traits as well, such as working ability.

Even a single under the table outcross can widen the gene pool and future breeding obtions considerably.

The "hot stud" phenomonen that we see also serves to further restrict the gene pool when equally beneficial males of other lineage are overlooked.

Lonny I hear what you are saying but amazingly, how many of those fat out of shape mutts you see around are 12-15 years old. I see it a lot. Those mutts just seem to live a long time, and you see or hear about the purebreds getting cancer at 6 and 7. I don't think its a wife's tale. It seems as though there is definately something to it.