Donkey color genetics are not well understood but are being researched more as breeding donkeys become more popular.
Also, with donkeys, “points” refers to the muzzle, rings around the eyes, belly, and upper legs. “Trim” refers to the mane, tail, and tips of ears.
When determining the color of a donkey, the main body color is what should be looked at first, then trim color and point color.
Also, most colors mentioned can be combined, for example: ivory gray dun. The most common and basic colors are mentioned.
Base Coats:
Black
The body is uniformly black.Can be homozygous(EE) or heterozygous(Ee).
Sorrel (Red)
Black pigment is suppressed and body color is a reddish color. Can only be homozygous(ee). Also Sorrel is recessive to black.
Dilutions:
The base colors can be diluted by the Ivory and Dun genes.
Ivory
Very similar to double diluted cream horses. It is characterized by a white or cream base coat with pink skin and blue eyes. If the animal is a dun carrier, the primitive markings, especially the dorsal stripe, can appear to be a light gray color. Ivory is a recessive gene. Also mottled or speckled skin around the eyes, nose, and genitals can be seen in Ivory donkeys. The ivory gene is rare, and breeders are constantly trying to improve the gene pool to reduce the number of inbred ivories.
Dun
Dun in donkeys is almost the same as dun in horses. The base coat is diluted to a faded color, and primitive markings are present.
Types of Dun are:
Gray Dun
A black base coat is diluted into a grey color. Trim and primitive markings are black or dark grey. Also, the base coat can appear black with a cross (the dorsal/shoulder stripe).
Rose Dun (Red Dun)
Red base diluted to a pale reddish color. Trim and primitive markings are a darker shade of red.
Bay Dun
Bay base coat is generally diluted to what is commonly called seal brown or just brown. It can be as dark as black with primitive markings visible. They have black trim and primitive markings.
Modifiers
Pangaré
Points are lightened. This is a very common gene in donkeys. Donkeys without pangaré are rare but do exist.
Agouti (Bay)
This gene has the same effect in donkeys as in horses. Only affects black pigment, and lightens the main body color to a brown/red color of varying shades. In most donkeys, only the trim is black due to pangaré lightening the points.
Modifiers
Donkeys only have two known white patterns, roan, and spotting.
Roan
Roaning causes white hairs to be intermixed with the base color of hairs. Affects red and black, but appears to be dominant in black and recessive in red. Different types of roaning such as frosted and varnish are not well documented. The main difference between roan in donkeys and horses is in donkeys, the head is often roaned.
Spotting
Spotting is dominant to non-spotting.Can only be heterozygous as homozygotes are non existant. The spotting is typically horizontally oriented and can cross the shoulders. Donkeys often have color spots within white patches. Blazes and socks in donkeys are a minimal form of spotting.
There have been no recorded cases of a sorrel donkey with the spotting gene, at least no visible signs.
Color generally stays around eyes, ears, topline, and generally on one or more leg. The leg markings may be broken or spotted. Blue eyes are unusual in spotted donkeys but it has occurred.
Donkeys with appaloosa-like spotting can be called tyger spotted, but is in no way related to the appaloosa genes.