This article
was published in the Oct/Nov/Dec 2013 newsletter of the North American Lionhead
Rabbit Club, The Mane Musings and updated 4 years late for publishing in the NARLC Guidebook. Although
I wrote it about BEW Lionheads, the genetics of the Vienna gene are the same
for any breed of rabbit and so are the breeding principles. I hope that you enjoy the article and ask
that you do not copy any of its content without permission. Thank you
Introduction
Breeding blue-eyed white Lionheads
has proven to be quite the journey for me since I started my project with this
variety four years ago. Challenging, but
also very rewarding, the BEW variety requires ample patience in addition to a
solid understanding of genetics, because of the intricacies of the Vienna
gene. This is an updated version of my
article that was published in the Mane
Musings in 2013.
Establishing a Breeding Program and Vienna Genetics
A blue-eyed
white breeding program should be treated like a completely different breed from
your other Lionhead colors in a sense, because you cannot use animals from your
BEW program with other color lines. Additionally,
you do not necessarily want to cross any color into your BEW program either,
without careful consideration. Breeding
your BEWs to a colored rabbit should only be done to improve the type/mane/etc.
in your BEWs and then all resulting offspring are Viennas and should be treated
as such. Having a Vienna color breeding
program will mean that you have many non-showable bunnies popping up, so make
sure you have a plan to move them on when needed. Breeding BEWs is a one-way street. Other colors can go in, but you cannot take
rabbits from your Vienna line and put them in a non-Vienna breeding program.
It is
important to understand the terminology used by BEW breeders.
BEW
– stands for blue-eyed white. It is a
pure white rabbit with bright blue eyes.
Vienna Gene – Expressed as “V” (regular) or “v” (Vienna).
VM – Stands for Vienna Marked or “Mismark Sport”. It is when a rabbit carries the Vienna gene
and shows it in spots of foreign color in the coat. This is never showable.
VC – Stands for Vienna Carrier. A rabbit that carries the Vienna gene but
does not show it. These are the most
important to clearly identify as Viennas to your customers and in pedigrees. You do not want someone thinking that their
Lionhead is just a regular solid colored rabbit and then get the Vienna gene
spoiling their color down the road.
The genetics of a BEW are as
follows:
----------VV
– “regular”, non-Vienna rabbit. Most Lionheads are VV and do not have the
Vienna gene.
----------vv – blue-eyed white.
It takes two copies of this gene to be a BEW.
----------Vv
– Vienna Mismark or Vienna Carrier. One copy of this gene may or may not show up
in the rabbit’s phenotype.
The Vienna gene is a masking gene
like REW. All the dashes in the genotype
are unknown genes that vary by the rabbit.
Like REWs, you can have BEWs that are genetically torts, chestnuts, otters,
harlequins, or any variety of colors hiding behind the white. Many BEWs do hide some of these more unusual
colors.
Gene Expression
How are BEWs the color that they
are? A BEW is white because the Vienna
gene wipes out the cells that produce pigment in the fur (melanocytes). A VM’s spots of white are literally spots
that do not have any melanocytes. The
eyes are blue for the same reason; the pigment in the iris of the eye is
normal, but the pigment in the stroma has a slightly different type of cell and
is missing melanocytes. The combination
of normal and missing pigmentation produces the effect of a blue eye. The blue is an optical effect – the eye is
not actually blue but appears that color much the same way that the sky appears
blue, but is not. Therefore, the blue eyes
can seem different shades in different lighting. True eye color is best evaluated in natural
sunlight.
BEW eye color also changes from kits
to mature animals. When the eyes first
open, they look very dark - almost black.
As they mature, the color slowly brightens. At what age the eye color stops changing
varies somewhat by the line, but many do by around 4 months of age.
Working with VMs and VCs
When you breed BEWs, unless you are
only crossing BEW to BEW, you will likely be working with VMs and VCs. The Vienna gene has incomplete dominance, so
if a rabbit carries one copy of the gene, the color expression can “turn off”
or “turn on” by mere chance. A VM can be
very subtle like a colored rabbit with a speck of blue color in the eye and a
white toenail, or it can be more dramatic with a blaze, color on the neck and
shoulder, and white feet, for example.
Although the markings are somewhat random, they still tend to follow a
pattern of typical depigmentation.
Blazes and nose spots of many different shapes, blue or partially blue
eyes, neck and shoulder markings, and white feet tend to be the most commonly
seen markings. Eye color on VMs varies
just as the spotting does. It is often
regular colored (brown or blue-gray), but can also be pure blue, or very often
partially blue or odd eyed.
VMs or VCs can be very valuable in a
herd. Many BEW breeders will
occasionally bring in a non-Vienna rabbit of compatible color genetics to
improve quality and bring in new blood.
It takes at least two generations working this way as the first
generation of kits will all be VMs and VCs. Vienna-marked and carriers can be
bred to a BEW for BEW offspring or with each other to achieve the same
goal. I do not recommend breeding a VM
or a VC to a non-Vienna rabbit because you will not get any BEWs and the number
of VMs will be too small to make the cross worth it. Some of the kits produced will not carry the
Vienna gene at all and these cannot be told apart from VCs without test
breeding first.
Purple Eye Effect
There are several causes of a purple
eye effect in BEWs. This happens when
additional factors contribute red to the eye color and, in combination with the
existing blue, can look purple overall.
A ruby cast is a common cause of
purple eyes. Shaded varieties that have
a ruby cast to their eyes like siamese sables, sable points, and smoke pearls
will cause this in addition to chocolate varieties such as chocolates, lilacs,
and chocolate torts. Homozygous Vienna
genes mask everything, but for some reason do not mask this ruby cast and it
will show right through the blue eyes. The
eyes resemble a red eye in a photograph from camera flash - but in real life. The ruby cast can be described like a
translucent red film in the pupil of the eye and it is somewhat
reflective. This effect is sometimes
described as purple eyes and it spoils the look of a blue eye considerably. The recessive nature of these genes make it
important to not only stay away from breeding in these animals with ruby cast,
but also ones that carry for it. A black
that carries chocolate, for example, can still introduce these genes in your
BEW herd.
BEWs can also have a different purple
effect in the eye, not to be confused with the ruby cast effect from chocolate
or shaded. These eyes are blue with
visible red/purple veins in them, and are believed to be caused by lack of
pigmentation in the iris. If you look at
the brown eyes in some rabbits, you will see that some are very dark and
uniform and others are lighter or possibly have somewhat uneven
coloration. This is the same lack of
pigmentation being expressed in a more subtle manner in other colors than
BEWs. By selecting away from the latter
coloration, the purple veining will disappear and the eyes will be a uniform,
brilliant blue.
Other Genes Avoided
There are also several colors that
many BEW breeders will avoid, not because they damage BEW color, but because
they make color identification much more difficult.
The first of these colors is REW
which is another masking gene. You can
have a rabbit that is genetically blue-eyed white and ruby-eyed white at the
same time, but they have ruby eyes because REW will cover patterns in all other
loci. Because of this masking, you do
not know if the rabbit genetically is a BEW, a VM, VC, or even non-Vienna
depending on the breeding they are out of.
It also makes your chances of getting actual BEWs in a litter slimmer
when some of them are double masked with REW.
The next color that many BEW
breeders avoid is broken. In some
crosses, many breeders will depend on retaining VMs rather than non-marked
babies so that they know they carry the Vienna gene and broken can mask this
very well as it is white on white.
Buyer Education
If you breed BEWs, it is very
important to inform all buyers of any BEW, VC, or VM rabbits. This should be clearly marked in the
pedigrees and I tattoo a “V” in the ear of any rabbit from my Vienna line
whether it is a BEW or not. There are
terrible stories of entire breeding programs being destroyed because the Vienna
gene was lurking behind colors and the breeder was unaware of its presence. Anyone who raises and breeds rabbits with the
Vienna gene needs to understand how damaging it can be if not carefully
controlled in its own program. They also
need to ensure that their buyers understand this as well.
Misconceptions with the Vienna gene:
Possibly more so than with other
colors, there are many misconceptions with the Vienna gene and BEWs in
general.
· It is a myth that BEWs are blind, deaf, or have
seizures. This may have been the case
early in the development in some breeds due to heavy in-breeding, but it is no
longer a problem at all. I have never
heard of this being an issue in the Lionhead breed.
· Dutch colored rabbits are not caused by the Vienna
gene. Although the blaze and other
patterning in a VM may closely resemble Dutch patterning, they are completely
unrelated genetically. VMs are sometimes
called “Dutch-Marked” which may lead to further confusion.
· A white rabbit with blue gray eyes or brown eyes is an
ermine or frosty with extremely light color.
Usually you can find these faintly colored hairs on the ears and a BEW
would never have them. A white rabbit
with blue gray eyes can easily be mistaken for a BEW.
· VMs are not brokens and cannot be shown or bred as
such. Using a VM as a broken in your
breeding program will be devastating. If
it is out of Vienna lines, do not cross it with your other colors.
· Although REWs and BEWs are both white, they are not at all
related.
· REW does not cause a purple eye effect. REWs that are hiding chocolate can pass
chocolate which produces this ruby cast or ones that have the genetics for
light eye pigmentation can produce the visible vein effect, but the REW gene
itself does not damage color.
· No other color genes appear to affect BEW color including dilute and chinchilla. BEWs with these genes behind them have blue
eye color equal to ones that do not.
Conclusion
