Roan (color)

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Different meaning: Roan, Norway.

A red roan horse.

Roan is a type of coat color in horses (and, occasionally, in other animals, such as dogs and cattle) that is a mixture of white hairs with a base coat of another color.

Contents

1 Roan in Horses
2 Lethal Roan Question in Horses
3 Roan in Dogs
4 Roan Cattle
5 See also
6 External links

Roan in Horses

Roan, caused by the roan gene, consists of single white hairs intermingled with the base color of a horse. It gives the horse a lightened appearance, while the mane, tail and head remain the original color. Roan horses also tend to have dark lower limbs, and the top of the dark area will have a pointed or triangular appearance. It is a dominant gene, meaning that at least one parent must be a roan in order to pass the gene on (it does not "pop out" from two non-roan parents with roan lineage).

The true roan gene appears in some breeds more than others. Roans are found in these breeds: Quarter Horses, Saddlebreds, Tennessee Walking Horses, Connemara Ponies, Miniature horses, American Paint Horses, Welsh Ponies (though rarely, if ever, in Welsh Cobs), Shetland Ponies. There are only two roan Morgan horses known to be alive today, a gelding and an aged mare, so the color is probably at a dead end in that breed. The true roan gene does not appear in Arabians and Thoroughbreds; colored individuals in those breeds are carrying Rabicano or Sabino rather than the "true" roan gene.

Red base (chestnut) + Roan = Strawberry Roan
Black base + Roan = Blue Roan
Bay (black base + Agouti gene) + Roan = Red Roan

Strawberry Roans usually have a pinkish tint. Red Roans are like strawberry roans except darker at the points (mane, tail, and lower legs). Blue Roans have a bluish tint. Roan can appear on any base color or mixture of colors, so there are also buckskin roans, silver dapple roans, etc.

Contrary to some belief, the varnish roan coloring is not caused by the roan gene, but the result of the varnish roan gene combined with an appaloosa (normally spots, blankets, etc.) coloring.

Lethal Roan Question in Horses

The idea of "Lethal Roan Syndrome" came from a 1979 study (Hintz, H.F. and VanVleck, L.D., published 1979. Lethal Dominant Roan in Horses. Journal of Heredity 70:145-146.) This study, based on percentages of roan foals thrown by roan parents, popularized the idea of Lethal Roan Syndrome. The study did not include direct genetic analysis and assumed fetus absorption preventing birth.

A recent genetic study of roans by Dr. Bowling (See http://www.hancockhorses.com/article-roanQHNews.pdf) refuted Hintz and VanVleck’s inferences. Using genetic analysis, Dr. Bowling found several homozygous roans and no evidence of a Lethal Roan Syndrome.

Roan in Dogs

The roan gene in dogs acts as a simple dominant gene. The action of the gene results in a mingling of colored and white hairs. To be roan a dog must have white areas; a solid colored dogs can not be roan. Breeds where the roan gene commonly occurs are English cocker spaniels, English setters, Australian Cattle dogs. The roan pattern also occurs in American Cocker Spaniels, Field spaniels and Border collies.

Roan dogs are more prone to deafness due to the absence of pigment present during ear formation. There are no other health issuses associated with this gene. Black and white roans are referred to as "blue roans" (spaniels) or "blue belton" (English setters). Red/buff and white roans are referred to as "red roans" "orange roans" or "lemon roans" or oran. Brown and white are referred to as "liver roans", "chocolate roans" or "brown roans".

Roan Cattle

The roan colour can also result in Shorthorn Cattle, but in a case of intermediate inheritance or Codominance. These cattle can not breed true, as this type of intermediate inheritance is also Heterozygous, or hybrid, as two different colour alleles are required form the parents to produce this particular coat colouring.

External links

Horses

[Photo of blue roan]
[Photo of grulla roan]
[Photo of chestnut roan]
[Photo of smoky black roan (black + 1 creme gene + roan)]
[Photo of palomino roan]
[Photo of silver dapple roan]
[Photo of strawberry roan]
[Photo of bay roan]
[Horse Coat Color Genetics] (Including roan definition, photos, and genetic formulas)
[Blue Roan Genetics and Photos]

Dogs