They are often confused for black and tan to those who haven't seen them before .
Their adult coat could be described like that of a GDS I suppose . All single black sable hairs start off golden /red at the root and along the hair shaft they become black .
A sable has golden hair under the belly ,on the chest and on lower legs ,and the back, thigh and upper arm are the sable colour as described above .
Here is an adult
I would not consider that to be sable to be honest. In border collies we would call this saddle pattern. A 'true' sable would not have such large areas of solid black and they would appear sable patterned from birth.
There are 3 variations of the agouti gene that occur....tan point, saddle pattern and sable, these are all patterns rather than colours so they can act on any base colour.
Here's some pics of my latest litter (which are all spoken for
) at 3 weeks old
http://www.flickr.com/photos/35934609@N03/sets/72157615882351806/They are all sables and tanpoints but there is no mistaking which is which even at this early age. The pale coloured sable is actually a blue sable (so the sable pattern is acting on a diluted blue base colour)
There's a pic of mum and dad in their too. He is sable and she is tan pointed, the pups are exactly what I expected colour-wise.
There is more than one gene that controls sable/tan point.
Here is the explaination of how it works from my website (sorry if it's a bit complicated but it's the simplest way I could explain it!)
Agouti - 'A' and Dominant Black - 'K'
This is the gene responsible for producing sable, seal, saddleback pattern and tricolour in border collies...there are numerous alleles of this gene and it is still not fully understood but I am concentrating on those that concern border collies.
ay - sable
at - tanpoint - recessive to ay (as such a tricoloured dog cannot carry sable)
As we already know each individual has two copies of each gene but this isn't quite as straightforward as some of the other genes we've mentioned...these genes exhibit variable incomplete dominance...
Genetically pure for sable (ay-ay) is generally clear sable in colour, while heterozygous (ay-at) is usually sable with some extent of darker fur in the coat (shaded sable). This is incomplete dominance (one copy of the recessive allele produces some effect).
ayay - clear sable
ayat - shaded sable
atat - tanpointed
But...it doesn't end there...there is another gene that effectively switches the agouti genes on and off...this is referred to as dominant black and is written as 'K'
It is thought that ALL border collies have the genes for sable and/or tanpoint but their ability to express and produce these colours is not only determined by their presence and combinations but also by those of the Dominant black 'K' genes.
KK - Homozygous dominant black, cannot be or produce sable/tanpoint regardless of the A alleles
Kk - Heterozygous dominant black, cannot be sable or tanpointed but can produce the patterns it carries on the A alleles
kk - Homozygous, will exhibit sable or tanpoint depending on it's A alleles
In conclusion...
KK atat - neither sable nor tanpointed, cannot produce sable or tanpoint but can pass the tanpoint genes on to offspring
KK ayat - neither sable nor tanpointed, cannot produce sable or tanpoint but can pass the tanpoint or sable genes on to offspring
KK ayay - neither sable nor tanpointed, cannot produce sable or tanpoint but can pass the sable genes on to offspring
Kk atat - carries tanpoint
Kk ayay - carries sable
Kk ayat - carries sable and tanpoint
kk ayat - shaded sable coat colour (also carries tanpoint)
kk ayay - clear sable coat colour
kk atat - tanpointed coat colour
Any solid colour can exhibit sable or tanpoint pattern (black, chocolate, blue, lilac); the pigmentation and eye colour of the dog will usually reveal it's base colour in the case of sables. Because the sable gene affects the extension of eumelanin (similar in effect to the extension gene) in it's extreme (clear sable) merling will not be visible, as such merle to sable matings are generally not a good idea.
