30/05/2026
A little colour genetics observation about Overflow Britannia..
Overflow Britannia’s base colour is bay, but I strongly suspect she may also carry the non-dun 1 (ND1) allele. This is often confused with dun, but they are not quite the same . True dun causes body dilution as well as primitive markings, whereas ND1 can produce some primitive markings (usually not as strong) without the characteristic body dilution.
I’ve suspected for some time that Rhythm (Brittania’s dam) may carry ND1 too. Interestingly, her sire, FS Don’t Worry, is actually a red dun, but as Rhythm has no body dilution and only a very faint dorsal stripe, I doubt she carries dun.
ND1 is fairly common in Connemaras. This is one reason why Connemaras with dorsal stripes are often mistakenly described as dun, when in reality many are simply displaying primitive markings associated with ND1 rather than carrying the dun allele itself.
One thing that makes ND1 particularly interesting is that the markings can be very subtle and are often seasonal. In Rhythm’s case, the faint dorsal stripe was most noticeable when she was shedding into her summer coat in early spring, whereas during other times of year it is difficult to see at all.
Primitive markings are often most obvious in newborn foals, which may explain why this filly’s dorsal stripe is currently so striking. As she matures, it may fade or become much less noticeable, but for now it is a really fascinating feature and another reminder that colour genetics are often more complex than they first appear!
Of course, without genetic testing this is only speculation, but it is certainly an interesting possibility
