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Great Dane Genetics

The GDCA Color Code

Let's take a look at the GDCA color code. The full text is available at http://www.users.cts.com/king/g/gdca/colrcode.html

The color code specifically prohibits certain crosses.

A Blue cannot be bred to a Fawn or Brindle. This eliminates tainting the Fawn/Brindle gene pool with the d blue-dilution allele. By eliminating this allele from that gene pool, we eliminate the risk of ending up with Fawn with blue masks, and of Brindles with blue masks and stripes. As a blue-masked Fawn or blue striped Brindle is not show-able, this prohibition makes sense from an AESTHETIC standpoint.

A Blue cannot be bred to a Harle, or Black-from-Harle. Again, we eliminate tainting the Harlequin gene poor with the recessive d blue-dilution allele. This eliminates any risk of producing "Harlequins" with blue torn patches instead of black. Again, and aesthetic decision.

A Fawn or Brindle cannot be bred into a Harlequin line. This eliminates having the recessive ay allele in Harlequin bloodlines. And eliminates the risk of "Fawnequins" or "Brindlequins." Again, aesthetics.

Not mixing Harle and Fawn/Brindle does accomplish one thing. It eliminates what are called "sable merles" in the herding breeds. These dogs appear sable (the same genotype as our Fawn) except the black tipping on the individual hairs shows an overall merled pattern. This pattern is easy to see in the puppy coat, although it is very difficult to see in the adult. Given that in Great Danes we have selected for modifiers to greatly reduce the black tippings on dogs with the ayay genotype, a "Fawn Merle" would be difficult to spot even with the puppy coat, and virtually impossible to recognize in the adult. This could lead to an unknowing and inadvertent Merle x Merle breeding, resulting in whites which may well be deaf. At last! Part of the GDCA color code that actually serves a valid health-related reason!

However, the GDCA color code SPECIFICALLY PERMITS:

- Harle X Harle (resulting in 25% MM whites, many of whom are deaf)
- Mantle X Mantle (potentially resulting in 25% swsw color-headed whites, some of whom are deaf)
- Mantle x Harle (potentially resulting in 25% swsw color-headed whites, some of whom are deaf.)

Does it not strike anyone be me as being very, very odd that our parent club would go to the effort of having a Color Code, but then have the vast majority of the reasons behind the code be purely aesthetic? And still SPECIFICALLY PERMIT those breedings that will inevitably produce puppies with sensory defects?

The Great Dane Club of Germany (DDC) specifically prohibited breeding Harlequin X Harlequin in the fall of 1995. This at least prevents (registered) litters that will result in the MM double merle genotype and its associated problems. In most herding breeding that have the M gene, is considered unacceptable to breed merle to sable (our fawn) for the reasons stated above-it's hard to recognize a sable-merle as carrying the M gene. And it's never acceptable to breed MerleXMerle.

So why does the GDCA color code ALLOW HarleXHarle (which is genetically MerleXMerle)? I don't know. But perhaps a closer look at the number of deaf white Danes coming through our country's Dane Rescue groups should cause them to reconsider this aspect of the color code, especially in light of the recent acceptance of the Mantle, widening the range of Champion dogs available to the Harlequin gene pool.

Author: Ana Greavu-Rachow