Spanish Andalusian Horse Articles > Color

There is No Such Thing as a Black Gene!

CAUTION - there are MANY "black" Andalusians that have not been tested to verify if they are truly black (E_aa)... use caution when breeding or buying!!!! We warned YOU! Verify the color using UC-Davis dna-results. Even well-known breeders can advertise their horse as "black" and be lying!

Unless a person can demonstrate that their horse is dna-tested, I will assume the horse is "black" (not verified) and questionable.

by Donna DeYoung.

I just got done surfing the web and doing some market research on dreamhorse . com. I tell you, I'm frankly a little perturbed by the, er, um, lack of quality of Andalusian horses on the market! Makes me want to scream, what is wrong with this breed! Okay. Calm down.

Now, while looking at some horses listed as black or black bay or chestnut or whatever, I see that several people are using the term "black gene" freely.

Here are some incorrect and misleading statements in horse advertising:

" ... horse carries the black gene ...". A-hem. There is no such thing.

" ... high color producer ..." listed for a bay stallion of all things. As far as I know, as long as you didn't breed the bay to a grey, you would always get "color" (something other than grey). So I guess that makes him a high color producer? But if you bred him to a heterozygous grey, you would have 50% chance of getting grey. And if you bred him to a homozygous grey, you would get GREY 100% of the time (no need to wait and see). Guess what I'm saying is don't take their word for it if they can't show you the UCDavis results and explain them they don't know what they're talking about.

" ... black bay ..." Is it black or bay? Which is it? Odds are it's a genetic bay that looks dark bay/black due to sooty or smutty or the seal brown modifier.

" ... black ..." Soooo.. Is it tested for black? Because the horse could be a seal brown, sooty bay, grey, or black bay and not really black.

" ... black tested ..." Soooo. Tell us the results?

And the most confusing of all, a chestnut horse wiith grey roaning flecks " ... does not carry the black gene so can only produce chestnut or bay unless bred to black ...has not been tested for the grey gene  ..."

I'm not sure what black gene they are talking about. The big E? (which obviously he doesn't have because he's a chestnut ee). or the little a? If it's both, eeAA. Then okay, but you could NEVER get black from him even if you bred him to blackl (eeAA x E_aa will not get you aa).

If he is eeAa or eeaa, then you COULD get black by breeding him to a bay that is EeAa.

If he is eeAA, then breeding to black would NOT give you a black! And if he is eeaa, breeding to black E_aa would get you black half the time and chestnut the other half.

So this person is all confused and it's making me confused.

This person got it right.

" ...solid BLACK (EE/aa)" Now I know it is black as long as it is not grey.

Here is the scientific explanation of the black vs. red vs. bay controversy as explained in Wikipedia.

The bay family of coat colors is dependent on two autosomal simple dominant genes: Extension and Agouti.

The role of the Extension gene is to produce a protein called Melanocortin 1 receptor or Mc1r. Mc1r allows the black pigment eumelanin to form in hair. (If your horse inherits big E, that's the eumelanin).

Closely tied to this process, the role of the Agouti gene is to produce Agouti signalling peptide Asip, which disables Mc1r, effectively allowing the red pigment phaeomelanin to "show through." However, this disabling does not occur throughout the coat; it occurs only in pulses on the body coat and not at all on the extremities or points. (If your horse inherits the big A, that's the agouti gene)

If a horse does not possess a functional, dominant copy of the wildtype E-allele at the Extension locus, then Mc1r cannot be produced. Without this protein, the black pigment eumelanin cannot form in the hair. Such horses, having two copies of the recessive mutation, have eumelanin-free, phaeomelanin-rich coats; they are red, or chestnut. (If your horse is little e little e "ee", he is red).

In summary, unless a horse has at least one functional E-allele, it cannot be bay.

Similarly, if a horse does not possess a functional, dominant copy of the A-allele at the Agouti locus, then Asip cannot be produced. Without Asip, eumelanin is unreglated and the coat is wholly black. The regulation of black pigment, though, is dependent on its presence in the first place; a horse with the recessive Agouti genotype aa is indistinguishable from any other genotype in a horse with a eumelanin-free coat. When eumelanin (E) is present, it is restricted in varying degrees by the action of Asip (A).

So, in other words, for a horse to be bay or black depends on TWO genes.

As for "black bay", this color shade is also known as seal brown. It may caused by the At and is only a "shade" of bay. It may also be caused by the addition of "sooty" or "smutty".

• a, the least dominant, must be homozygous to be observed and is responsible for unrestricted black coat (non-agouti black),
• A^t, only visible in the homozygous form or when paired with a, is responsible for the black-and-tan seal brown coat,
• A, visible when homozygous or when paired with a or A^t, is responsible for the standard bay coat,
• A+, dominant, is responsible for the wildtype wild bay coat.

WARNING - unless an owner verifies by UC-Davis DNA testing (or another verifiable laboratory), do not BELIEVE that a horse is black just because they say so or the horse looks black. Colors in photographs can be doctored and horses can be died.  "Black Bays" or sooty bays look very much like pure blacks.

About the author:

Donna DeYoung is an "Andalusian Expert" and raises Pura Raza Espanola (PRE) horses on her Texas farm. She is an avid dressage and endurance rider and enjoys teaching others.

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