Friday, January 27, 2012

Mismark Case Study: Pembroke Welsh Corgi

A Pembroke Welsh corgi with a tail in the most commonly seen color: red and white. Image is from Wikimedia Commons under a Creative Commons license.
The Pembroke Welsh corgi is a herding breed that is a favorite of the Queen of England. It comes in far fewer colors than its cousin, the Cardigan. It also comes in several mismarks. The breed standard only allows for red, sable, and black and tan, all of which may or may not come with white markings. Here are the mismarks seen in the breed:
  • Too much white
    • Dogs with white that crosses into the main body or onto the ears
  • Whitelies
    • Dogs that are mostly white
  • Bluies 
    • Dilute dogs: instead of black, the coat is gray/blue
  • Black without tan points
    • Though mentioned in the standard, it may not be present in the breed
  • Blue eyes
    • Possible thanks to white on the head or independent genes
This corgi has too much white
As is so often the case all of the mismarks listed (except black) are caused by recessive genes. Since the breed is most often seen with fairly heavy Irish white markings, there is a fair possibility that dogs expressing this phenotype may have very different genotypes. For example, a copy of the solid gene plus a copy of the extreme white gene will produce a dog with Irish white markings. This is well known in boxers, and may be quite possible in the corgis. If two of these dogs were bred together, a "whitelie" would be inevitable.The same is true of mismark dogs that have too much white, but too little white to be considered a whitelie.

This corgi is a bluie
The blue dilution is a purely recessive gene. You have to have two dogs who carry the gene to produce a dog with blue coloration. However, since it is recessive it is basically impossible to breed the color out, since half of the puppies from any litter that produces a "bluie" will likely carry the blue gene. If line-breeding or other forms of inbreeding are done in the future, then more bluies are very likely to show up. In addition, trying to breed out a recessive gene is truly a pointless endeavor since doing so would cause a great reduction in the number of dogs available for breeding in a closed population.

This corgi has too much white
As I have been saying with all of these case studies, breeding for color is honestly the last thing that a breeder should be doing. A dog with a white ear will not be any less healthy than a dog with a red ear or a black ear, and the dog with the white ear is being penalized for a mere silly cosmetic difference. In addition, purebreds are bred in closed registries and as such genetic diversity is a serious concern. By eliminating dogs from a gene pool simply because their color is not what is considered "ideal," genetic diversity is being dropped for a pointless cosmetic reason. In addition, If corgi breeders want to continue with insisting that their breed is a capable herder, why bother with color? Color will make no difference whatsoever when it comes to the dog's ability to herd. A blue dog will be able to herd just a well as a black one. However, the mismarks continue to be penalized and kicked out of shows.

1 comment:

  1. Well said. What are your thoughts on tail docking?

    ReplyDelete