Equine coat color genetics

The color of a horse is based on two base colors: red (chestnut in color) and black. It is off these two colors that all the other coat colors are formed. Black is formed by the E locus, and is dominant over red. EE and Ee are black, ee horses are red (chestnut). Black foals are usually a mouse-brown color, that sheds out to black.

The genes affecting color

• The Agouti Gene (A): bay coloration, which is always on a black base.

• The creme gene (Cr): Produces palomino, cremello, buckskin, and perlino. Also smoky black and smoky cream.
  • The creme gene on red base: palomino and cremello

  • The creme gene on black base: smoky black and smoky cream<p>
  • The creme gene on bay (black base with the agouti gene): buckskin and perlino<p>
  • Is an incomplete dominant gene <p>

• The champagne gene (Ch): amber, gold, classic, and ivory.
  • The champagne gene on red base: gold <p>
  • The champagne gene on black base: classic <p>
  • The champagne gene on bay (black base with agouti): amber <p>
  • The champagne gene on cream (the creme gene): ivory <p>
  • Is a dominant gene

• The silver dapple gene (Z): black silver, red silver, bay silver
  • The Silver gene on black base: black silver <p>
  • The Silver gene on red base: red silver <p>
  • The Silver gene on bay (black base with agouti gene) : bay silver <p>

• The dun gene (D): grulla, red dun, bay dun
  • The dun gene on red base: red dun <p>
  • The dun gene on black base: grulla <p>
  • The dun gene on bay (black base with agouti gene): bay dun <p>
  • Is a dominant gene

• The white gene (W): white
  • One copy of the gene produces a pure white horse <p>
  • Two copies of the gene are lethal <p>
  • See Gray (horse) for more information on white horses <p>

• The roan gene (R): strawberry roan, red roan, blue roan
  • Roan on red: strawberry roan <p>
  • Roan on black: blue roan <p>
  • Roan on bay (black base with agouti): red roan <p>
  • One gene copy will produce roaning <p>
  • Two copies are lethal <p>

• The Rabicano gene (Rb)
  • Causes white hairs on flanks and top of tail, sometimes on ribs as well

• Gray gene (G): gray (including dapple, rose, fleabitten)
  • See Gray (horse) for more information <p>
  • Any color (any base, or base + combination of above genes) + Gray= gray <p>
  • The gray gene creates a process in which the horse changes gray. It is not born that color. <p>

• The Tobiano gene (T):
  • causes a white pattern where white crosses over the spine

• The Overo gene (O):
  • Is dominant <p>
  • Is lethal in its homozygous dominant form (lethal white syndrome) <p>
  • White markings appear at belly and spring upward <p>

• The Sabino gene (Sb):
  • Homozygous Sabinos are usually almost completely white

• The splashed white gene (Spl):
  • Differs from overo in that the legs are white <p>
  • Has white face with blue eyes <p>

• Brindle

• Appaloosa:
  • The genetics for this coat coloring is still not completely understood

• Flaxen:
  • The genetics for flaxen is not yet understood
  • The flaxen gene lightens the mane and tail of horses

The colors diluted

Creme gene (C):

• Dilutes the red base coloring to gold when one copy is present
• Dilutes red base to cream when two copies are present
• Can dilute black base with two copies

Champagne gene (Ch):

• Dilutes red base to gold color
• Dilutes black base to liver/chocolate color
• One or two copies present has no affect on final color of the horse

Silver dapple gene (Z):

• Dilutes black base: mane and tail to flaxen, coat to chocolate

Dun gene (D):

• One or two copies has no affect on the final color of the horse
• Seems more concentrated in diluting the body than the mane, tail, or head
• Similar to the creme gene, but also produces primitive markings: red to gold

The genes in coloring

Chestnut/Sorrel: ee, also Aaee or AAee (A is not shown because the horse has no E (black) coat)<p> Black: E (EE or Ee) <p> Bay: A-E (AaEe, AAEe or AAEE ) <p> Zebra Dun: A-E-D (E= black color, A restricts it to the points, D=dilutes the colors and adds dun factors) <p> Red Dun: aa-D-ee (ee= red coat, D= dilutes color, adds dun factors) <p> Grullo/Grulla: aa-D-E (E=black coat, aa is recessive so does not restrict it to points, D=adds dun gene) <p> Palomino: Crcr-ee (ee=red coat, Crcr=dilutes red color once) <p> Buckskin: Crcr-E-A (E=black coat, A=restricts black to points, Crcr=dilutes the red on the horse) <p> Cremello: crcr-ee (ee=red coat, crcr= dilutes red color twice) <p> Perlino: crcr-E-A (E=black coat, A=restricts black to points, crcr=dilutes the red on horse twice) <p> Smoky Black: Crcr-E-aa (E=black coat, aa=recessive so doesn't restrict it to points, Crcr= dilutes the red once, but no red on black horse) <p> Black Cream: crcr-E-aa (E=black coat, aa=recessive so doesn't restrict it to points, crcr=dilutes the red twice, but no red on black horse) <p> Red Silver: Z-ee (ee=red coat, Z=dilutes black on horse, but there is no black on a red horse) <p> Black Silver: Z-E-aa (E=black coat, aa= recessive, so does not restrict to points, Z=dilutes black on horse) <p> Bay Silver: Z-E-A (E=black coat, A=restricts black to points, Z=dilutes the black on horse--the points) <p> Gray: G or Gg (G= any coat base or any modified base is turned gray) <p> Strawberry Roan: R-ee (ee=red coat, R= roan affect) <p> Blue Roan: R-E-aa (E=black coat, aa= recessive, so does not restrict black to points, R= roan affect) <p> Red Roan: R-E-A (E=black coat, A= restricts black to points, R= roan affect) <p> Rabicano: Rb (Causes rabicano on any base coat or modified base coat) <p> Tobiano: T (TT or Tt- causes Tobiano pattern on any base or modified base) <p> Overo: O (OO or Oo- causes overo pattern on any base or modified base) <p> Sabino: Sb (SbSb or Sb- homozygous SbSb is usually completely white) <p> White: Ww (Ww on any base or modified base will produce white, WW is lethal) <p> Classic Champagne: Ch-E-aa (E=black coat, aa=recessive so doesn't restrict to black points, Ch=champagne dilution) <p> Gold Champagne: Ch-ee (ee= red coat, Ch= champagne dilution) <p> Amber Champagne: Ch-E-A (E= black coat, A= restricts black to points, Ch= champagne dilution) <p>

See also

• Agouti gene, bay coloring
• palomino
• cremello
• buckskin
• roan
• The creme gene
• The champagne gene
• The silver dapple gene
• The dun gene
• Gray (dapple, rose, fleabitten, regular) and White: Gray (horse)