Inheritance of the four basic coat colours
in Shetland Sheepdogs.
This is intended as a basic reference for anyone intending to bred shelties. The topic of coat colour inheritance can be very controversial at times, but if the colours are correctly identified then there should be no problems. Please bear in mind that the percentages are taken from a large numbers of litters in many different lines, so the percentage of colours in individual litter may vary.
For simplicity sake, Shelties may be considered as carrying two colour genes. This is definitely not true, but the theory holds for basic genetic analysis. For example, the "blue merle" gene is actually a combination of several genes (polygenic effect), but all are inherited in a linked fashion. If you are interested in the genes involved with coat colour please see my more detailed page here. The four main colour genes are:
Sable (S)
Tricolour (T)
Blue Merle (BM)
Technically, there should also be a Black and Tan gene, but this colour more or less died out. I haven't heard of a B & T sheltie in the last 30 years - feel free to email me if anyone knows of one out there. Shaded sables are classed as tri-factored sables.
We breed all four colours of shelties - many of whom can be seen on our Cinbaramy homepage. Some people have mentioned problems with identifying Black and Whites, but if the coat colour under the tail, behind the ears and under the chin is checked and no tan found, then the pup is Black and White. If any tan is present, then the dog must be denoted as a Tricolour. The inheritance of the Black and White gene is poorly understood, but it appears to be carried as shown below:
Pure Sable x Pure Sable = 100 % Pure Sable
Pure Sable x Tri-factored sable = 50 % Pure Sables + 50 % Tri-factored Sables
Tri-factored Sable x Tri-factored Sable = 25 % Tri + 25 % Pure Sable + 50 % Tri-factored Sable
Bi-factored Sable x Bi-factored Sable = 25 % Bicolour + 25 % Pure Sable + 50 % Bi-factored Sable
Pure Sable x Tricolour = 100 % Tri-factored Sables
Pure Sable x Bicolour = 100 % Bi-factored Sables
Tri-factored Sable x Tricolour = 50% Tri-factored Sable + 50% Tricolour
Bi-factored Sable x Tricolour = 50 % Tri-factored Sable + 50 % Tricolour
Tricolour x Tricolour = 100 % Tricolour
Tricolour x Tricolour with bi gene = 100 % Tricolour
Tricolour with bi gene x Tricolour with bi gene = 75 % Tricolour + 25 % Black & White
Tricolour x Black & White = 100 % Tricolour
Tricolour with bi gene x Black and White = 50 % Tricolour + 50 % Black & White
Blue Merle x Blue Merle = 50% Blue Merle, 25% Tricolour and 25% Double Merle
(weak/ absent merle factor may cause appearance of tricolour)
Blue Merle x Tricolour with bi factor = 50 % Blue Merle & 50 % Tricolour
Blue Merle x Tricolour = 50 % Blue Merle & 50 % Tricolour
Blue Merle x Black and White = 50 % Blue merle + 50 % Tricolour
Blue Merle with bi gene x Black and White = 50 % Blue Merle + 50 % Black and White
Black & White x Black and White = 100 % Black and White
Having said all this, nature is her own master and many mutations may occur throwing weird and wonderful colours - please see page with further details of complicating colours. Any photographs (with permission to use if possible, whether you prefer them acknowledged or anonymous) of more unusual marking such as cryptic / sable / maltese merles, CHW, double merles etc. would be much appreciated.
Please click Lucky for a list of recorded colours
of
GB Show Champions in Shetland Sheepdogs.
