[pyrnet] Re: pyrnet-l-digest.20020708-1

[Rhonda Collins <rhonda@castlepublishing.com>]

A
> Hi Joe, Barb and Linda,
>
> This is an extremely interesting thread. I am of course no expert in
> dog
> coat colorations, but I have done some research in Horses. I was
> wondering
> if some of the same genetics as far as colour genes may be similar.
> Please
> excuse my intrusion and ramblings as I'm thinking out loud here.
> Horses I'm sure you know is an animal where extensive study has been done
> on
> the subject, as people strive to guarantee certain colour and coat
> patterns...i.e.: Paints, Appaloosas, Palomino's etc. Although they do
> not
> always get the desired results :(
>
> As in horses, true white horses (albino) are very rare. Most white
> horses
> are actually grey horses which have faded to white. The same is true
> for
> black horses. A black horse is also extremely rare (except in the case
> of
> breeds like the Friesian who breed for it) most black horses are actually
> a
> very dark brown.
>
> Linda's extreme piebald theory seems like a very good explanation, as
> I've
> never read the book she mentions and it may explain further detail
> and
> suggest a similar explanation..... I would also suggest for discussion,
> that
> maybe they also have the dominate "greying" gene or a
> "dilution" gene as
> well.
>
> Which might explain why alot are born with color, and it fades as they
> age.
> Firm rule in horse breeding, you never breed a Grey horse to a Paint if
> you
> want the coloration to stay. Or a Palomino (dilution gene) to a Paint
> for
> the same reason.
>
> In the case of the dilution gene, if is homozygous, it will result in
> any
> colour becoming diluted to a very pale cream or white.
> Appaloosa breeders steer away from the dilution factor as it lightens
> the
> dark pigment, so there is little or no contrast between the white and
> the
> colour in the horses coat.
>
> According to Ann Bowling, PHD at the Veterinary Genetics laboratory at
> UC
> Davis; "Despite the great variety in coat colours, they're all
> created by
> the presence or absence of two pigments, eumelanin (black/brown) 
> and
> phaeomelanin (red/yellow). It's believed that these two pigments may
> be
> influenced by other genes that can alter the coat colour, diluting it
> or
> producing patterns."
>
> So in theory, maybe Pyr's are actually not white but have the colour
> gene's
> (red/yellow) or (black/brow) pigment in a Overo coat pattern and 
> the
> dilution gene, which makes their coat fade to either white or white
> with
> pale colouration. Or the combination of the greying gene with the
> piebald.
>
> Again just thinking out loud.
> Sariena

I was thinking along the lines of horses as well, as I'm much more
knowledgeable as far as color breeding in horses. I bred Arabians for a
while, and with Arabs, all white or gray horses are born a darker color
and fade to gray or white. And an Arab that is born black or bay but has
the gray gene will also have a black skin. I've never seen an albino
Arab. Come to think of it, I've never heard of one, either.

This also brings up my previous question: Do all Pyrs have the white skin
with black spots? That could also be a clue a to the genetics of
color.

Rhonda