This one doesn't say what you should do. It gives breeders a way to
think more specifically about their choices.
http://dogplay.com/Breeding/breeder_worksheet.html

--
Diane Blackman
There is no moral victory in proclaiming to abhor violence
while preaching with violent words.
http://dog-play.com/ http://dogplayshops.com/

wrote in message ...
This one doesn't say what you should do. It gives breeders a way to
think more specifically about their choices.
http://dogplay.com/Breeding/breeder_worksheet.html

--

Hi Diane,
An excellent worksheet. I recommend your web-site often as it's well-written
and full of good information.

I'm wondering if you should add some questions that would encourage a
potential breeders learn more about their particular breed:

"All breeds have health problems, what are the hereditary health problems
found in your breed?"
(In theory, it would make the breeder do a little research - perhaps get
involved with the breed community.)

"What tests are available to determine the health/genetic status of your
breeding dogs?"
(OFA's, Genetic testing, etc).

And for the folks who want to get into the Designer Dog thing (Puggles,
'doodles, etc.), perhaps something about how hybrid vigor doesn't work the
way they probably think and that knowing the genetic health of the purebreds
is a good thing.

BTW, on Collie-L we were discussing one "designer breed" that didn't work
out the way the breeder intended: A person bred a litter of "Golden
Collies" - Golden Retriever / sable Collie cross and was mystified and
peeved that all the pups came out black. She didn't know that even though
both the Golden & Collie are sort of alike in color (i.e. both
golden/reddish brown), the genetics behind the Gold in the Golden Retriever
and Sable in a Collie are totally different and all Golden / Collie mixed
puppies will be black. Hard to market a "Golden Collie" that is black and
from what we heard, this "Designer Breed" fad was short-lived. (Hurrah!)
Though, I would've liked to seen one of these pups as an adult - I wonder if
it would look like a Faux Flat Coated Retriever.

Chris and her smoothies,
Pablo and Lucy

chris jung wrote:

And for the folks who want to get into the Designer Dog thing (Puggles,
'doodles, etc.), perhaps something about how hybrid vigor doesn't work the
way they probably think and that knowing the genetic health of the purebreds
is a good thing.

BTW, on Collie-L we were discussing one "designer breed" that didn't work
out the way the breeder intended: A person bred a litter of "Golden
Collies" - Golden Retriever / sable Collie cross and was mystified and
peeved that all the pups came out black. She didn't know that even though
both the Golden & Collie are sort of alike in color (i.e. both
golden/reddish brown), the genetics behind the Gold in the Golden Retriever
and Sable in a Collie are totally different and all Golden / Collie mixed
puppies will be black. Hard to market a "Golden Collie" that is black and
from what we heard, this "Designer Breed" fad was short-lived. (Hurrah!)
Though, I would've liked to seen one of these pups as an adult - I wonder if
it would look like a Faux Flat Coated Retriever.


There's a connection between these two paragraphs: that's how "hybrid
vigor" actually works--it tends to bring up dominant traits, like black
coats. In principle, when hereditary health problems are simple recessives
and highly breed-specific, crossbreeding would reduce them. In real life,
of course, many health problems are polygenic and occur in both parent
breeds of a cross.

Amy Dahl

Amy Dahl wrote :
chris jung wrote:
BTW, on Collie-L we were discussing one "designer breed" that didn't
work out the way the breeder intended: A person bred a litter of
"Golden Collies" - Golden Retriever / sable Collie cross and was
mystified and peeved that all the pups came out black. She didn't
know that even though both the Golden & Collie are sort of alike in
color (i.e. both golden/reddish brown), the genetics behind the Gold
in the Golden Retriever and Sable in a Collie are totally different
and all Golden / Collie mixed puppies will be black. Hard to market
a "Golden Collie" that is black and from what we heard, this
"Designer Breed" fad was short-lived. (Hurrah!) Though, I would've
liked to seen one of these pups as an adult - I wonder if it would
look like a Faux Flat Coated Retriever.

There's a connection between these two paragraphs: that's how "hybrid
vigor" actually works--it tends to bring up dominant traits, like
black coats.

That's not how hybrid vigor works, although it my be the common
misperception of both what hybrid vigor is and how it works.

In principle, when hereditary health problems are simple
recessives and highly breed-specific, crossbreeding would reduce them.

Crossbreeding would mask them in the first cross. The ratio of
undesirable alleles in the total population would remain unchanged from
that of the parent generation. After that, randomness reigns.

In real life, of course, many health problems are polygenic and occur
in both parent breeds of a cross.

Amen

Mary Healey wrote:

Amy Dahl wrote :


There's a connection between these two paragraphs: that's how "hybrid
vigor" actually works--it tends to bring up dominant traits, like
black coats.

That's not how hybrid vigor works, although it my be the common
misperception of both what hybrid vigor is and how it works.

OK, care to straighten me out? My understanding is based mainly on
Malcolm Willis, and I thought I had correctly summarised his
explanation. Heterosis, a.k.a. "hybrid vigor" is the expression of
more dominant traits in a cross (a.k.a. F1 generation) than in the
parents, when the parents are assumed to be from separate, linebred
strains with greater than average homozygosity. Correct?


In principle, when hereditary health problems are simple
recessives and highly breed-specific, crossbreeding would reduce them.

Crossbreeding would mask them in the first cross. The ratio of
undesirable alleles in the total population would remain unchanged from
that of the parent generation. After that, randomness reigns.


I figured Chris knew that, but it does bear pointing out. "Hybrid vigor"
is a fleeting effect seen in one generation only. Subsequent generations
can be expected to be highly nonuniform and subject to all of the
complaints of both original breeds.

Amy Dahl

Amy Dahl wrote :
Mary Healey wrote:
Amy Dahl wrote :
There's a connection between these two paragraphs: that's how
"hybrid vigor" actually works--it tends to bring up dominant
traits, like black coats.

That's not how hybrid vigor works, although it my be the common
misperception of both what hybrid vigor is and how it works.

OK, care to straighten me out?

Sure. I thought you put "hybrid vigor" in quotes because you knew that
that wasn't how it works g.

My understanding is based mainly on
Malcolm Willis, and I thought I had correctly summarised his
explanation. Heterosis, a.k.a. "hybrid vigor" is the expression of
more dominant traits in a cross (a.k.a. F1 generation) than in the
parents, when the parents are assumed to be from separate, linebred
strains with greater than average homozygosity. Correct?

No. Heterosis has nothing to do with genetic dominance, and is more
accurately used when traits are measurable, continuous, and there is an
overall deviation from the parent average in the offspring. "Either/or"
traits like color don't have heterosis.

For example, breed a Hereford bull (big, fast-growing, red with white
face) to an Angus cow (smaller, slower-growing, usually all black). The
offspring are pretty predictably going to be black with white faces --
the black color from the dam and the white markings from the sire are
dominant to whatever they get from the other side. That's not
heterosis. But if those F1 crosses also tend to grow faster than what
you'd expect by averaging the growth rates of the parents, then they
display heterosis for growth. Say the bull's growth was 1.5 lb/day and
the dam's was 1.0 lb/day (and I'm making these up!). You'd expect the
calves to grow at 1.25 lb/day or so. If they consistently make 1.4
lb/day, then there's heterosis. If they consistently only gain 1.1
lb/day, that's also heterosis, but it's not commercially useful.

So, heterosis is specific to certain traits, and the same animal might
display heterosis for one trait and not for others. "Hybrid vigor", as
it's most often misused by the general public, tends to be a catchall
phrase intended to mean "generally superior to the parents".

Following this thread (I am new to the NG, obviously), but I have a
question about the inherited
and/or genetic diseases that are inherent in certain breeds.

We had a 10 yo Golden that died last week from Hemangiosarcoma. From
what we have seen
out on the web, this particular cancer (besides being very aggressive)
affects German Sheaprds
and is starting to impact Goldens more and more. Sure enough, I spoke
with the owner of the
breed bitch a couple of nights ago and learned that two of our dogs
littermates had also
succumbed to cancer. All three were males.

Some veterinary articles on the web mentioned a genetic marker that had
been discoverd that
is an indicator for this cancer. I know that there are certain
conditions that a dog is checked for
and it is the due diligence of the prospective owenr to insit on (Hips,
eyes). Is genetic testing
for hereditary conditions something that you see becoming an issue in
the future?

Thanks for your responses,

Joe Cipale

Mary Healey wrote:


No. Heterosis has nothing to do with genetic dominance, and is more
accurately used when traits are measurable, continuous, and there is an
overall deviation from the parent average in the offspring. "Either/or"
traits like color don't have heterosis.

[remainder of explanation snipped]

OK, thanks. That does actually ring a bell..."exceeding the mid-parent
mean" or something like that.

Apparently my retention of this information is not as good as I thought.
I appreciate the correction.

Amy Dahl

On Fri, 23 Jun 2006 10:31:49 GMT chris jung whittled these words:

I'm wondering if you should add some questions that would encourage a
potential breeders learn more about their particular breed:

snip

I appreciate the input. My number one goal was to keep it short. I'm
trying to think of a canine genetics book that would not address the
importance of knowing the problems of a particular breed. Same with the
hybrid vigor issue. Hmmm well in any case maybe if I can convince someone
that there are things to gain by learning more it will become a habit.

BTW, on Collie-L we were discussing one "designer breed" that didn't work
out the way the breeder intended: A person bred a litter of "Golden
Collies" - Golden Retriever / sable Collie cross and was mystified and
peeved that all the pups came out black. She didn't know that even though
both the Golden & Collie are sort of alike in color (i.e. both
golden/reddish brown), the genetics behind the Gold in the Golden Retriever
and Sable in a Collie are totally different and all Golden / Collie mixed
puppies will be black. Hard to market a "Golden Collie" that is black and
from what we heard, this "Designer Breed" fad was short-lived. (Hurrah!)

LOL - one of the Willis books discusses a cross breeding with similar
results.
--
Diane Blackman
There is no moral victory in proclaiming to abhor violence
while preaching with violent words.
http://dog-play.com/ http://dogplayshops.com/

wrote in message ...

Ok, I feel like a *major* oaf for barging in on this thread to ask this, but
here goes anyway:

Diane, am I remembering correctly that you are near the Bay area? I have a
training client who is moving there next week. They are a lovely couple who
are really attentive to their new pup's needs (an adorable French Bulldog)
and they are looking for a trainer to continue with out there. I was hoping
you (or anyone else reading this) might know of a group (and a dog walker,
since they are trying to locate those as well) or at least help point them
in the right direction.

Sorry for the barge in and thanks for your indulgence on that one. My brain
went blank about just where to post this, and I saw your post and just hit
"reply".

TIA,
Tara