Understanding and Working with the Vienna Gene
The gene responsible for creating the blue eyed white is called the Vienna gene and is expressed in genetic code as vv. This gene is believed to be neither dominant nor recessive, as it lies hidden in certain cases. When you breed a BEW to a BEW, statistically speaking, you'll get 100% BEW. However there are exceptions:
(1) When Himalayan or REW lies hidden, you can get phenotype REW.
(2) If shaded, chocolate, or lilac lies behind the BEW you can get BEWs with a ruby cast pupil, and these offspring are not showable. You can, therefore, breed almost any color into your BEWs to improve type, with the exception of your shaded colors, chocolate, and lilac. These colors, and rabbits with these colors in the back ground, should be avoided to prevent the ruby cast pupil. It has often been a misconception that breeding a REW to a BEW would cause a ruby cast. This is not the case. A REW will not cause a ruby cast to a BEW’s eyeas long as the REW is not hiding shaded, chocolate or lilac. REWs can be an excellent color to use to cross into your BEWs, but you must know what is behind them.
When you breed any color beside BEW to BEW, you will get what are known as Vienna Marked (VM's) or Vienna Carriers (VC). A VM or VC is expressed in genetic code as Vv. A Vienna Marked and a Vienna Carrier are genetically the same. They both carry only one Vienna gene. The distinction is that a VM is a rabbit that you can look at and clearly see he carries the gene because he will have white “marks” on him, and/or blue, or partially blue eyes. On the other hand, a VC will have no outward marks. There will be a problem if you breed a VC/VM to a VC/VM cross. This crossing will result in some "normal" offspring, "Normal" refers to a non-Vienna carrying rabbit. There is no way to know which ones could be VC's that didn't get a white marking, and which ones are just plain normal without the Vienna gene. Any offspring from a cross like this should always remain in a BEW program or be sold as pets only. Breeding one of these animals back into other colors is a big no-no. They will cause major problems for years in the lines with white spots and white nails. BEW is like a one-way street almost anything can come in, but nothing can go out. Should you sell a VC, VM, or possible VC to someone it is important to record on the pedigree that the animal has, or could possibly have the Vienna gene. It is also your responsibility as an ethical breeder to explain what this means to the person buying it.
Below is a chart that shows what you can statistically expect when breeding BEWs.
BEW X BEW = 100% BEW (or REW masking BEW - This is still genetically a BEW)
BEW X "Normal" = 100% Vienna carriers, 0% BEW
Vienna Carrier X Vienna Carrier = 25% BEW, 50% Vienna carriers, 25% "Normal"
Vienna Carrier X BEW = 50% BEW, 50% Vienna carriers
Vienna Carriers X "Normal" = 25% Vienna Carriers, 75% "Normal", 0% BEW