WHAT MAKES GREY (G)
What Makes Grey (G)
Possible Color Genotypes/Black & Black-to-Grey
Possible Color Genotypes/Bay & Bay-to-Grey
Possible Color Genotypes/Chestnut & Chestnut-to-Grey
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All Arabian horses start out black, bay, or chestnut. If a dominant allele for grey (G) is present, the horse will gradually and progressively show a silvering of the hair, usually starting with the head. G is always dominant over all other colors so if the horse has only one G allele, it will turn grey as it ages.
Most often a horse that is a grey will have at least a few white eyelashes when it is born. Its foal coat will be the base color of black, bay or chestnut but usually with an intensity of color not typically seen in those colors until after the usual foal coat is shed. (It is not unusual for a base coat of bay to be mistaken as black or chestnut, especially if the foal's coat greys quickly.) Sometimes the foal will start greying immediately or maybe even wait until it is much older to show a color change, but the eyelashes are the key. If you see ANY white eyelashes AND a parent is grey, the registration color should probably be--and could almost be guaranteed to be--grey. (However, if a foal is originally recorded as black, bay, or chestnut on its registration papers and then greys, the registry will change the color--at no cost to you--if you provide them with photos of your horse. It is difficult (if not totally impossible) to get the color changed from grey back to black, bay or chestnut. If there is any question as to if the foal is a color or grey, it would be best to register the foal as the color and change it later.)
Knowing the base color of a grey horse is very helpful in determining its color genotype. Since the coats of grey horses are somewhat different at birth from those of the other colors, it takes careful observation to be sure to get it correct--especially if the horse greys quickly. These will be addressed in Possible Color Genotypes of Black-to-Grey, Chestnut-to-Grey, and Bay-to-Grey where each base coat is taken into consideration before the horse greys out. Sometimes, when no record is available, the base coat color of a grey can be determined based upon the color of non-grey offspring.
Since the color alleles to produce grey are dominant and all alleles are received from at least one parent, to be grey means at least one parent MUST be grey. The only possiblity of the horse being homozygous for grey is if BOTH parents are grey and BOTH pass along the G allele. ALL grey tail-female Sahanad horses, except Ashmere Dahin and Dahin Aziza, have had only one grey parent and therefore could not be homozygous for grey. (Ashmere Dahin and Dahin Aziza MIGHT be homozygous grey, but neither has had a foal as of this date--a colored foal would mean that mare was NOT a homozygous grey and they never will.)
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Special Note on Roaning: Roaning is NOT the same thing as greying. Roaning is controlled by genes at a different loci. Roaning is the effect of white hairs throughout the body--the head usually remains dark with very little change. Some roaning is quite common and usually found on the sides and flanks. Usually these hairs are not easily visible from a distance but can be seen upon close examination. If the roaning is very strong and evident from a distance, the horse might qualify to be registered as a roan by the registry. The Sabino gene is involved in some of the roaning and not discussed here.
What Makes Grey (G)
Possible Color Genotypes/Black & Black-to-Grey
Possible Color Genotypes/Bay & Bay-to-Grey