I believe they can now DNA for grey in Britain but it is not yet commercially available. All of us who DON'T want grey but who have a couple of heterozygous grey mares in the broodie band because they are just too good in all respects apart from the colour, will be waiting eagerly for the test to become commercially available so we can test foals and say by a few months of age whether or not the horse will grey out. I was reading somewhere -maybe here - that linking the grey DNA test to the overall genome of the horse reveals that all grey horses descended from one common ancestor tens of thousands of years ago, or even further back. I believe they can trace to a common ancestor via the mitochondrial DNA. One horse had a mutation in the ordinary colour genes that caused the complete loss of colour in the hair at an early age, and that single horse bred that colour mutation on until it is evident in nearly all breeds of modern horse. Interestingly, this gene must have gone through further mutations (my assumption) as we now have some lines of greys that go completely white by the time they are four or five, some that stay steel grey until they are over ten, some that go flea bitten grey, etc. Perhaps that single first grey mutation also had a mutation in the T-cells that attack cancer cells (by coincidence or perhaps the location on the DNA is adjacent) so that all grey horses develop cancer cells/tumours/growths easily whereas the other colours have the very active and normal T-cell production to detect any cancer cells early and deal with them. I am sure there will be further exciting research into this which may well carry over into the understanding and treatment of human cancers. I've been meaning to chat to Tintara about this and pick her brain on the topic (my knowledge comes from picking brains of people like Tintara!) Leanne O.