GREYING GENE In Sheepadoodles (G LOCUS)
Both the Poodle and the Old English Sheepdog can carry the greying gene on the G Locus. Many of our puppies will turn grey as they age, which typically starts at around 6 months of age. If you adopt a dark coloured sheepadoodle from us, you should be prepared for greying & fading! The gene causing greying has not yet been located, although work has begun in locating a similar gene in horses, which may eventually shed some light on dog greying.
For a little background…
The greying gene occurs on the G locus. It’s thought to be an incomplete dominant, so G is greying and g is non-greying, and in order for a dog to express greying it only needs to have one copy of G (so its genotype can be Gg or GG). GG will generally have a stronger effect on the coat than Gg. A dog that doesn’t express the greying gene has the genotype gg. Greying is expressed on long, curly and wire-haired coats only, so a short-haired dog may have the gene but show no sign of it.
The greying gene, like dilution, affects eumelanin (black and liver). However, unlike the dilution gene it doesn’t actually affect the nose or eye colour, it is progressive (so a dog with greying is born solid black or liver and becomes lighter as it gets older), and it doesn’t always affect the whole of the coat to the same extent (the shade of grey in different parts may vary, and some parts may even remain black). A dog with the dilution gene may have greying as well, but it’s rare for the two genes to occur in the same breed. Greying doesn’t affect phaeomelanin (red) to the same extent.
Sometimes breeds which have the greying gene also come in shades of cream, which suggests that the lightening of the two types of pigment is connected. However, as the rich tan on some Yorkshire Terriers proves, there is not necessarily a strong connection. Red is generally lightened by the intensity (I) series, and some breeds simply carry both greying and phaeomelanin dilution.
One last interesting thing to note about greying is that while it affects dogs with tan markings (saddles, traditional tan etc) it does not always affect masks. Kerry Blues are a striking example of this – their main coat may turn to silver while leaving the hair on their muzzle solid black. It’s not known why this happens, but it could be that E-locus black (such as masks) just isn’t affected in the same way by greying as K- or A-locus black.