Simply put, a “Dunalino” is a Palomino who carries a dun gene. Except as these things always are, it’s a bit more complicated than that!
The dun gene allele is a dominant one, so the phenotype of a horse with either one or two copies of the gene is dun. Because it is a dominant gene it will always show, so two non-dun parents cannot produce a dun foal (because they won’t have a dun gene).
The dun dilution effect is caused by pigment only being placed in a part of each hair. Specifically, body hairs only have pigment along one side of them, while hairs from darker parts such as the dorsal stripe have pigment all the way around. Dun was the original colour of horses, but most horses today are non-dun.
A primary characteristic of the dun gene is the dorsal stripe, and most duns also have visual leg striping. The shoulder stripes are less common and often fainter, but usually visible on horses with a short summer coat
There are two forms of non-dun colour, non-dun1 (nd1) and non-dun2 (nd2), caused by different mutations. Non-dun1 horses have some primitive markings, while non-dun2 horses do not. It is thought that the non-dun2 genetic mutation occurred after domestication, whereas dun and non-dun1 predate domestication. This table explains it best.
|D/D||2 copies of Dun. Horse will have Dun dilution and express primitive markings. Dun will be passed on 100% of the time.|
|D/nd1||1 copy of Dun and one copy of nd1. Horse will have Dun dilution and express primitive markings. Horse can pass on Dun dilution or primitive markings without dilution.|
|D/nd2||1 copy of Dun and one copy of nd2. Horse will have Dun dilution and express primitive markings. Horse can pass on Dun dilution with primitive marking 50% of the time.|
|nd1/nd1||2 copies of nd1. Horse will not be Dun diluted. Varying levels of primitive markings are present. Horse will pass on nd1 100% of the time.|
|nd1/nd2||1 copy of nd1 and one copy of nd2. Horse will not be Dun diluted. Varying levels of primitive markings are present. Horse will pass on nd1 50% of the time.|
“Bella” (HW Dancing Queen) has been colour tested as having a dun gene and a non-dun2 gene. (D/nd2). This makes her a “Dunalino” rather than a “Palomino” because she has a dorsal stripe and very faint primitive markings. Her dun gene has clearly come from Lola, her mum, because Lola is a red dun. Tinsel King (her sire) is buckskin so he therefore doesn’t have a dun gene. Having said all that, regardless of her unusual colour, Bella is pretty special anyway! It will be interesting to see what her final coat shade is when she’s an adult. We’ll keep you updated!