Reading a Horse Coat Color DNA Panel Result

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By Bikash Roy

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Bikash Roy

Online Research Specialist · SEO Strategist · Web Developer

Bikash personally verifies every calculator against official standards (WHO, NIH, government data). Online research specialist, SEO strategist, and web developer with 10+ years building accurate digital tools.

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· August 17, 2026

A coat color panel tells you what the horse carries. It does not tell you what the horse looks like — you already know that — and it does not tell you what a foal will be. Both of those are things you work out from the result.

The notation

• Uppercase is the dominant allele, lowercase the recessive: E over e, A over a
• n means no copy of the variant. n/Z is one silver allele; n/n is none
• Two identical letters is homozygous; two different letters is heterozygous, and a heterozygous result always hides something

That last point is the whole reason to test. A heterozygous horse looks exactly like a homozygous dominant one and behaves completely differently as a parent.

A worked panel

Visible color: bay, likely with a lighter mane and tail from the silver.

Read in order, the useful conclusions are:

1. Two hidden recessives. E/e and A/a mean this bay can produce black foals and chestnut foals. Neither is visible on the horse.
2. Silver will show here. Silver acts on black pigment, and a bay has black points — so expect a lightened mane and tail. On a chestnut the same result would be invisible.
3. Frame overo n/n is the line that clears a breeding decision. This horse cannot contribute a frame overo allele, so it is safe with a carrier. Why that matters is set out in frame overo and lethal white testing.

Turning it into a prediction

With both parents’ genotypes, the horse color calculator does the interaction for you. Set each locus to what the panel reported and read the predicted phenotype.

By hand, work in this order:

1. Extension first. If either parent can pass e, chestnut foals are possible.
2. Agouti second, but only for foals that can make black pigment.
3. Dilutions third. Each acts on the base color you just determined.
4. Whitening and spotting last. Grey overrides everything eventually; frame overo is a safety question rather than an aesthetic one.

The order matters because later genes need earlier ones to act on. A dilution has nothing to do until the base color exists.

What a panel does not cover

Not every variant is tested. Panels cover the well-characterised loci. Modifiers that affect shade, sootiness, and the exact expression of a pattern are largely not on any commercial panel.

Expression varies even with a known genotype. Two horses with identical results can look noticeably different. Genotype sets the range, not the exact outcome.

Pattern genes are especially variable. This is precisely why frame overo status has to be tested rather than assessed by eye.

Common confusions

“It says n/Z for silver but my horse is chestnut and looks normal.” Correct — silver needs black pigment. The allele is there and will pass to foals. This is the mechanism behind colors that seem to skip a generation.

“Agouti says A/a but my horse is chestnut.” Also fine. Agouti is inherited and reported regardless of whether it has anything to act on.

“Two different labs used different notation.” Common. N/N, n/n and -/- may all mean the same thing depending on the lab. Check the report’s own key rather than assuming.

If a result does not seem to match the horse in front of you, the explanation is usually that the gene has nothing to act on — the coat color loci reference lists what each one needs before it becomes visible.