The Grey Color Gene in Horses


I own a homozygous grey stallion, Patrick.  Both of his parents were grey. All of his offspring will be grey.

This is because the grey gene is a dominant gene and it removes all other color from any horse that carries the gene.

The foals are born chestnut, bay, black, and could even be pinto depending on the color gene from the mother, but over time they will become grey.

This process can be very rapid or take years.  We have some foals born with big grey rings around their eyes and grey or silver legs and some grey already showing on their body and before they are a year old they are completely grey and in some cases almost white.

The first foal by Patrick was born bay with a black mane and tail and black legs with a little star on her forehead.  Within days of her birth she had grey rings around her eyes and by the time she was 4 months old she was steel grey.

Pluto – 3 months

The next foal that was born bay took 3 months for any grey to appear on her face and still looked bay from a distance at 1 year of age.

The foals that are born chestnut go through some beautiful colors before they eventually loose the red in their coats.

I really like the rose grey and wish it would stay that way, but it always fades and they will eventually be white.

Patrick was white when I bought him at 4 years of age – including his mane and tail.  Most grey horses do not turn white so quickly, but a few of his offspring are.

A daughter of Patrick’s was bred to a black stallion and she produced a bay filly.

Because the mare only had 1 grey gene, she was able to pass on a bay gene from her mother to the filly, which means that the filly will not turn grey.

I learned that bay foals are born with light or silvery colored legs which later turn black, but foals that are born bay and turning grey have black legs (like the first foal of Patrick’s).

So a homozygous grey horse will only produce grey horses because that is the only color gene they have and so all their offspring will get a grey gene which will cause them to turn grey over time.

Pluto – 2 years

A non-homozygous grey horse has a 50% chance of producing another grey horse because they also carry another color gene.

Unlike other colors, a grey horse will always have a grey parent.

Also, grey is actually an over color, not a color.

The grey gene changes the original color over time, but it is never the original color ( like a white or albino).

Many breed registries require a grey horse to be recorded as the color they were born – turning grey – as in my horse’s KWPN registration – “schimmel vos geboren” – “grey born chestnut” so that the original color of the horse is recorded.

Now you know all about the grey color gene.  If you like grey horses, I have a few 🙂

Leave me a comment below and let me know about your grey horses

, , , ,

No comments yet.

Leave a Reply