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How to Tell the Difference Between Bay and Chestnut Horses.

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As I watched some horses go around on a walker, I thought they all were bays. But then I noticed one of them maintained the same brownish shade over its entire leg. This made me wonder if it was a bay or chestnut horse.

Bay and chestnut horses often have similar reddish-brown coats, but only bay horses have black points. The black points are the animal’s ears, mane, tail, and lower legs. On the other hand, a chestnut horse doesn’t have any black hair.

The horse that piqued my interest was registered as a chestnut. This blog post discusses the differences between bay and chestnut horses and includes some information about their genetics.

Picture of a bay horse on a walker.
Bay colt
Picture of a chestnut gelding.
Chestnut gelding

Features of a bay horse.

Bay horses are typically characterized by their copper-tone coats combined with black skin, black points, and dark eyes. The shades of bay horses vary from light brown to dark red. They are among the most common horse colors and are found in various breeds, including the American Quarter Horse, the Arabian, and the Thoroughbred.

Genetics of a bay horse

Many people believe that bay is a base equine color, while others think there are only two black and chestnut, and that bay is a variation of black. To create a bay coat, there must be a specific combination of genes, including the E allele and agouti. These genes are dependent on each other to produce a bay horse.

All bay horses have at least one E allele gene.

Horses have three base coat colors, chestnut, bay, and black. These colors are controlled by the E gene and the A gene. Black pigments are expressed genetically by “E.” Bay horses have at least one E allele gene, which can be either E/E or E/e.

In horses, the bay gene is dominant over black, and its expressed by either E/Aa or E/AA. All bay horses have a minimum of one gene that causes the production of black pigments. Another gene that plays a significant role in bay horses is the agouti.

The agouti gene directs black pigments in bay horses.

The agouti directs the distribution of black pigments. Dominant agouti (“A“) results in the black base color “E” restricted to the points of the horse. The horses’ legs, mane, tail, and ear tips are points.

This genetic combination results in a standard bay-colored horse, a reddish body with black points. The agouti gene has limited ability and only directs black pigments; therefore, chestnut horses are immune from its influence.

Picture of a dark bay horse.
Bay Thoroughbred

There are many different variations of bay horses.

Bay horses are some of the most popular horses around, and it’s no wonder why. Their striking coat color comes in a wide range of shades, from a rich golden hue to deep chocolate brown.

While the bay color is mostly determined by genetics, a few things can affect its shade. For example, bay horses that are poorly nourished may have a duller coat, while those that are well-groomed may have a richer color.

The more common bay colors are listed below:

  • Standard Bay
  • Sandy Bay
  • Bay Dun
  • Bay roan
  • Blood Bay
  • Amber Champaign Bay
  • Silver Bay
  • Bay Pinto
  • Bay Leopard
  • Mahogany Bay
  • Wild Bay
Picture of a chestnut horse.
Chestnut Thoroughbred

Characteristics of a Chestnut Horse.

Chestnut horses come in all sorts of different shades, from light honey to red, so dark it’s almost black. One thing these equines have in common is their lack of black hair- a coat pattern created by genes that suppress black pigments.

However, like bays, chestnut horses typically have black skin. However, some chestnut foals are born with light skin that darkens. Chestnut horses are true-breeding, so if you breed two chestnut horses, they will always produce a chestnut foal.

If the colt is any color other than chestnut, then one of the parents wasn’t a chestnut. However, both parents don’t have to be chestnuts to produce a chestnut foal.

The chestnut coat color has an extensive range of shades, some as light as a palomino to so dark they appear black. Their points (manes, tails, ears, and lower legs) may be darker or lighter than their bodies.

Chestnut horses are genetically identified as Genotypes E e E e A A A ‐ or E e E e A a A a. In other words, EeEe results in chestnut horses regardless of the other influencing genes.

Picture of a chestnut horse with a flaxen mane.
Chestnut horse with a flaxen mane.

Bay or Chestnut horse, how to distinguish.

Most bay and chestnut horses have a reddish, brownish coat. However, the horse’s color pattern is different; bay horses have black points, and chestnut horses don’t. Not only do chestnut horses not have black points they don’t have black hair anywhere.

Both bay and chestnut horses can have dark eyes and skin. A genetic test can also determine a horse’s coat color. Genetic tests are available from several companies and can evaluate your horse’s genotype with 99% accuracy using only a small snip of hair.

The most common genetic testing is called “DNA” or “genetic profiling,” which uses DNA samples taken from the inside of the hoof wall (called an “enzyme digester”) or from skin cells on the underside of their tails. 

After collection, samples are forwarded to one of the numerous specialized labs worldwide for analysis. They’ll look at all sorts of things such as eye color, temperament traits like aggression/friendliness toward people or animals, etc.

Picture of a two year old bay filly.
Bay filly

Conclusion

We hope this article has given you a better understanding of how to tell the difference between a bay and a chestnut horse. Of course, many factors go into determining the color of your horse’s coat, but we hope this information will be helpful for you.

Below is a helpful YouTube video that explains the basics of horse coat colors.

FAQs

What makes a horse a bay?

Black points are the distinguishing feature of a bay horse. A horse’s points are its lower legs, mane, tail, and ear tips.

What color horse was Secretariat?

Secretariat was a big chestnut thoroughbred stallion. He had such a distinctive red color that his nickname was “Big Red.”

What are chestnuts on horses?

Have you distinguished between the two horse colors yet? Share your views with us!