1. Horse Color & Genetics Reference: http://www.equinecolor.com Evans, W., The Horse,2ed. 1990 “Genetics: Color inheritance, Parentage testing, Genetic Lethals”, pp.472-536

2. Black phenotype Black bodies Black points Black horses without any brown or red hairs

3. Black genotype 1. Genetic Information a.Black pigment = Eumelanin (yoo-MEL-a-nin) b.Black is one of the base colors for horses, the other is red (Chestnut). All horses will have a black or red base color. The control for Black is located at the Extension locus and is dominant at that locus. Black horses are not capable of producing Bay foals unless the mate is a Bay or a Chestnut masking Agouti. c.Black at the Extension locus is symbolized by "E", since it is dominant. Chestnut is also located at the Extension but it is recessive so it's symbolized by "e". d.EE means the horse is genetically (homozygous) and physically Black* e.Ee means the horse is genetically (heterozygous) and physically Black* f.ee means the horse is genetically and physically Chestnut* g.*These horses are physically Black or Chestnut when there are no dilution or modifying genes present.

4. Chestnut Phenotype Red bodies Red points –Flaxen Light mane tail Sorrel –Accepted color in AQHA

5. Chestnut (red) Genotype 1. Genetic control of Chestnut is fairly simple to understand. a.Base coat color b.The recessive gene (labeled "e") resides at the Extension locus. EE =Black Ee =Physically black ee = Chestnut 2. Point color on Chestnuts doesn't seem to be controlled by a single gene. a.Flaxen is thought to be caused by a recessive gene and is unique in that it only affects red pigment.

6. Gray Phenotype More accurately Grey is a modifier Ongoing process of depigmentation of the colored hairs Grey slowly removes the pigment from the base color Black base coat with white diluting hairs throughout the body

7. Gray Genotype 1. Grey has the unique ability to mask everything including any Pinto or Appaloosa patterns. 2. No color is safe when Grey is present, as all horses that carry the Graying gene will end up a shade of grey or white. For this reason some breeders do not like to have mares or stallions in their breeding herd. 3. Gray is dominant GG = Gray Gg = physically grey gg = no dilution (base coat appears)

8. Bay Phenotype Red body, ranging from light to dark Black legs from the hoof to the knee and hock –Sometimes extending above the knee and hock. The mane and tail will also be black. –Bay horses generally have black ear tips also. "Wild" Bay –the black points are restricted lower on the legs, to varying degrees.

9. Bay Genotype Bay – Black horse with a restrictor or modifying type gene. This locus is called Agouti. –Agouti restricts the black pigment to the "points" of the horse, or the lower legs, mane and tail. Agouti locus –A+ = wild bay –A = Bay –a t = seal brown (black with brown points) –a = black

10. “Black” Bay Black Seal Brown Chestnut Grulla Dun BuckskinPerlino Dun or Brown Grulla Diluted seal brown Red Dun PalominoCremello DD Dd AA Aa t Aa EE Ee Dd DD aa atatatat ataata Dd DD Cc cr c cr No agouti affect

11. Dun Phenotype Bay base color Dun dilutes –Bay base color –Dun dilution Black Red pigment Dun dilution causes different types of Dun Primitive markings –Dorsal stripe –It may or may not have Zebra stripes on legs Transverse stripe over wither

12. Dun Genotype Dilution gene Dominant dilution Affects Black, Chestnut, and Bay DD, Dd = Dun dd = no dilution

13. Grulla Phenotype Black Dun Primitive markings –Dorsal stripe –Zebra stripes on legs –Transverse wither Mousey gray

14. Grulla Rare gene No Agouti gene dilution –Therefore the Black base coat appears DD, Dd = Black Dun dd = no dilution

15. Palomino Phenotype 1. Golden yellow Ideal New United States gold coin Shades light to dark Born very light to white Pink skin at time but will darken Brown to light amber eyes It may take several years for a horse to turn golden 2. White mane and tail 85% white No more than 15% black/brown hairs

16. Palomino Genotype Cream dilution –Present on the albino locus (not albino) –Appears in conjunction with Agouti –Recessive gene--somewhat –CC = Base coat will appear Black, Chestnut, or Bay –Cc cr = Cream dilution Palomino –Base coat = chestnut with dilution

17. Buckskin Phenotype Light bay Gold to yellow coat Black points No dorsal stripe

18. Buckskin Genotype Cream dilution –Present on the albino locus (not albino) –Appears in conjunction with Agouti –Recessive gene--somewhat –CC = Base coat will appear Black, Chestnut, or Bay –Cc cr = Cream dilution Buckskin –Base coat = bay with dilution

19. Perlino Phenotype Light or pink skin White or cream colored hair coat Mane, tail and legs slightly darker than the body Blue eyes

20. Perlino Genotype Cream dilution –Present on the albino locus (not albino) –Appears in conjunction with Agouti –Recessive gene--somewhat –CC = Base coat will appear Black, Chestnut, or Bay –Cc cr = Cream dilution Palomino or Buckskin –c cr c cr = Highest dilution Bay base coat and dilution = Perlino

21. Cremello Phenotype Light or pink skin White or cream colored hair coat Mane, tail and legs crème Blue eyes

22. Cremello Genotype Cream dilution –Present on the albino locus (not albino) –Appears in conjunction with Agouti –Recessive gene--somewhat –CC = Base coat will appear Black, Chestnut, or Bay –Cc cr = Cream dilution Palomino or Buckskin –c cr c cr = Highest dilution Chestnut base coat and dilution = Cremello

23. White trait Causes patterns –Appaloosa –Overo –Tobiano –Lethal gene? Modifying Gene –Masks color –WW = birth terminated –Ww = white hair coat, pink skin –ww = No white, ie. Color expressed

24. Appaloosa Phenotype/Genotype Pattern –Leopard –Blanket –Snowcap –Snowflake –Varnish roan –Frost Mottled skin –Grey, pink patterned skin Striped hooves White sclera around the eye W ap W ap = Leopard W ap w ap = other pattern w ap w ap = no pattern

26. Overo Phenotype/Genotype “Frame” –White framed by color Wild irregular pattern Less likely symmetrical –Typically does not cross the topline –Crop-outs occur Recessive gene –o e o e = Lethal Gene –oo, oo e = patterned horse –Oo e, Oo = non Patterned horse, but carrier –OO = no pattern

27. Tobiano Phenotype/Genotype Vertical pattern crossing the topline –White between the ears and tail –Head usually solid color –Round patterns Dominant Gene –TT, Tt = Tobiano – tt = normal expression (color) –Both parents should be Tobiano to get a Tobiano

28. Lethal Genes 1. Homozygous Dominant White Gene Result of heterozygous cross WW = not born Ww = white horse ww = color expressed 1. OLWS Overo Lethal White Syndrome –Carried full term –Born totally white some may have a tiny spot or two of color. These foals have an incomplete lower colon Foals cannot defecate Die of colic shortly after birth A positive test of the gene Recommends to euthanize Frame gene Recessive gene –o e o e = Lethal Gene –oo, oo e = patterned horse –Oo e, Oo = non Patterned horse, but carrier –OO = no pattern

29. Roan Pattern caused –White hairs mixing with colored hairs Non-progressive color –Visible by a few months of age –May become darker –Seasonal change Head, legs, mane and tail solid color RnRn =Lethal (before birth) Rnrn = Roan rnrn = no expression