"Blue" CorgisThe Summer 2002 issue of "Our Corgi World" featured an anonymous article with the following, abbreviated, content:
The Pembroke at my feet is blue! Would you recognise a blue Corgi? For the past years many Corgi fanciers and judges have seen my Corgi and found all sorts of faults, but never his colour. My Corgi was shown to a longstanding and respected breeder/judge with the remark that there was something strange with the dog. Could she say what it was? She couldn't.
When my blue Corgi was still a puppy, I wrote to Pat Curties, an experienced breeder, who was not in any way involved with the breeding of my Corgi. I sent her a few photos and asked for her opinion. Her answer came promptly, my Corgi was without any doubt a blue Corgi.
The blue merle colour occasionally also turns up in Pembrokes, possibly because Cardigan and Pembroke now and then were interbred in the early days. One or both eyes can be blue although this is rare.
This is a misconception and Pat Curties (Lees Corgis), who died in August 1999, doubted that bluies resulted from blue mere breeding in the distant past.
1. The blue merle colour of the Cardigan is caused by the M-gene. "M" causes partial dilution of the dark pigment to blue, leaving some areas untouched, while "m" produces the normal colour. M is dominant.
A blue merle Cardigan is basically a modified tricolour. A normal tricolour Cardigan will have the gene pair "mm", the blue merle Cardigan is carrier of "Mm", ie. the black colour is marbled with irregular blue-grey patches and the iris of one or both eyes is often blue or blue flecked. The sight is normal.
Blue merle Cardigan
If you put a tricolour Cardigan to a blue merle Cardigan you will, theoretically, get half tricolour and half blue merle puppies.
If you mate two blue merles, about a fourth of the puppies will theoretically have the gene pair MM.
Double merle (MM) Cardigan
MM-puppies are also blue merles but often with a lot of white, so-called whiteleys, that can be blind and/or deaf. Therefore, many countries do not allow matings of blue merles to other colours than tricolour or black and white (with brindle points). "mm" puppies are normal tricolours or black and white with brindle points and cannot pass on the merle gene.
2. In a blue Pembroke, a so-called bluie (or bluey), on the other hand, the colour is caused by the "d" gene. The dominant D gene has no influence on the pigmentation while "d" acts as a dilute. "d" is recessive, i.e. both parents must be carriers (Dd), to produce a blue Corgi (dd).
Bluies can occur in any colour (red, sable or tricolour). The red ones are said to be born a light fawn, almost milk chocolate colour, while the black and tan or tricolour ones are being an attractive squirrel grey. When they moult into full adult coats these go black with a gunmetal blue hue, whilst the red ones become a rather soft, dusty light red. It can be quite difficult to recognise an adult bluie, except for their slate coloured noses, lip pigment and eye rims and light or bluish eyes.
The "d" gene is also present in Cardigans. Dogs with "dd" have the dull blue-grey in the coat where normally there would have been black. Nose, lips and eye rims are a slate grey and again the eyes are light or bluish.
One or rarely two blue eyes in corgis of other colours than blue merle have nothing to do with the "d" gene. This type of blue eye follows a different pattern of inheritance and occurs in the approximate proportion of one out of sixteen from parents that carry the recessive genes for this blue eye.
3. In Cardigans we have another dilute colour caused by the "b" gene which occasionally produces a liver or chocolate coloured dog. The genes controlling the liver or dudley colour are designated as B and b. B is dominant and allows the normal black to develop, while b causes its modification to brown or liver. "b" is recessive so that both parents must be carriers (Bb) to produce a liver puppy.
In dogs with bb the black colour in the coat is replaced by liver. Also the colour of the nose, lips and eye rims is affected, they are brown, and the eyes are light or yellowish.
Pembroke Corgis on the other hand only carry the dominant pair BB for black (Clarence C. Little: The Inheritance of Coat Color in Dogs, 1957) so there will be no liver coloured Pembrokes.
It is difficult to avoid these dilute colours as you cannot see whether a dog is carrier of one of these genes, but once the colour appears in a litter you know that both parents are carriers of this recessive gene. (A DNA-test is now available for finding out whether a Cardigan is carrier of the liver "b" gene.) But although bluie Pembrokes, grey dilute and liver Cardigans are not showable and should not be bred, they are absolutely normal and healthy corgis, in other words a colour that is not conforming with the standard is not a disease.
And, by the way, neither the liver nor the grey dilute colour in Cardigans are caused by too many blue merles in the pedigree unless some of these were carriers of the "b" or "d" gene.
Thanks to those who allowed me to use the photos of their dogs.