All Ponies have either one of the three base coat colours Black, Bay or Chestnut.

They then can have other colour genes that cause different effects on that base coat colour. Below is information on the known colour genes that are found in the Highland Pony breed and how they affect the coats colour.

Extension – The Black Factor.
This is called the Red/Black factor. All Highland Ponies coat colours begin with either red or black based pigmentation. Ponies can carry a number of dilution patterns and/or modifiers that can affect the overall look of a pony’s coat colour but they all have genetics for red or black.
The Red/Black factor is tested through the extension gene.
EE = Homozygous for black. This means this pony is unable to produce red based of spring no matter what colour the other parent is.
Ee = Heterozygous for black and red. This means this pony has a 50% chance of either passing on the black gene or the red gene to its offspring.
ee = Homozygous for red. This means this pony will pass on the red gene no matter what as it has no black gene.

The Agouti Gene.
The agouti gene controls the distribution of black pigmentation. On black based ponies (EE & Ee) the agouti gene causes the distribution of black to the points of a pony (lower legs, manes and tails) On homozygous red based ponies (ee) agouti has no effect so fair for is hidden.
The Agouti gene
AA = Homozygous for agouti. This means this pony will pass on the agouti gene to its spring.
Aa = Heterozygous for agouti. This means this pony has a 50% chance of passing on the agouti gene to its offspring.
aa = Only recessive allele detected. This means this pony has no agouti gene and cannot pass it on to its offspring.

The Dun Dilution.
The dun dilution gene is a dominate gene and cannot be hidden on any coat colour, by lightening base body coat while leaving the legs, mane and tail darker. The gene is also associated with primitive markings and the dorsal strip down the middle of a ponies back is the most recognisable marking associated with being a dun. A pony can also show ear tipping, zebra striping to the legs, shoulder striping, guard hairs in the mane, tail and legs (guard hairs are a layer of pale outer hairs that sometimes can be very noticeable on certain dun ponies) and face masks.
The Dun gene
DD = Homozygous. This means this pony will pass on the dun gene to its spring.
Dd = Heterozygous. This means this pony has a 50% chance of passing on the dun gene to its offspring.
dd = Negative. This means this pony has no dun gene and cannot pass it on to its offspring.

The Silver Dilution.
The silver dilution gene is a dominate gene over black based ponies (EE & Ee), it does not show on red based ponies (ee) and therefore can be hidden. The silver gene varies greatly through the different coat colours but typically it will cause lightening of the mane and tails to give a silver/flaxen appearance and on a uniformly black pony it will typically cause the dilution of the ponies body to a chocolate colour (often with dapples), whereas on a bay pony you will get the lightening of the mane, tail and body, the same as a black, but also lightening of the legs, causing the pony to easily be mistaken for a liver chestnut. A yellow dun carrying the silver dilution gene can also easily be mistaken for a flaxen chestnut.
The Silver gene
ZZ = Homozygous. This means this pony will pass on the silver dilution gene to its spring. This pony will show the silver dilution traits, mentioned above, unless they are a red based pony.
n/Z = Heterozygous. This means this pony has a 50% chance of passing on the silver dilution gene to its offspring. This pony will show the silver dilution traits, mentioned above, unless they are a red based pony.
nn = Negative. This means this pony carries no silver dilution gene and cannot pass it on to its offspring.

The Grey Gene.
The grey gene is a dominate gene and is responsible for the progressive fading of a pony’s coat colour resulting in the complete greying of the pony. The grey gene is considered to be the strongest of all the genes and will dominate over all coat colours and dilution genes. The process varies per pony some may take only a couple of years before turning completely grey and others may take ten years or more. You will hear terms such a cream dun, grey dun, steel grey, rose grey and dapple grey to name a few but in the end all of these ponies will eventually be completely grey.
The Grey gene
GG = Homozygous for grey. This means this pony will turn grey and will pass on the grey gene, meaning all its offspring will also turn grey.
Gg = Heterozygous for grey. This means this pony will turn grey and has a 50% chance of passing on the grey gene to its offspring.
gg = Negative for grey. This means this pony will not turn grey and cannot pass the grey gene on to its offspring.

The Pangare Gene.
The pangare gene causes the mealy effect. It causes pale hairs around the eyes, muzzle and underbelly. These pale hairs can extend into the girth area, flanks, chest, throats and up the hind quarters. On red based ponies it can also lighten off the mane and tails giving a flaxen like appearance.

Written by Amy Young

For a more comprehensive explanation and photo examples please visit our website www.beinnkaldy.com.au