01 Sep Brindle Horse: Coat Pattern, Breeds, & Genetics

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Brindle Horses: Coat Pattern, Breeds, And Genetics

You may have seen a brindle dog, but have you ever seen a brindle horse? If it surprises you to hear that a horse can be brindle, you are not alone! Due to their rarity, many equestrians have never seen or even heard of brindled horses…I know I haven’t! They do exist, however, and the pattern is quite striking on a horse.

What is the brindle coat pattern in horses? While extremely rare, a horse can have a brindled coat. This will appear as either darker or lighter stripes over the base coat, mainly concentrated along the neck, shoulders, and hindquarters. The stripes are irregular and usually have a unique and wiry texture distinct from the hairs of the base coat. Brindle is one of the rarest coat patterns found in horses, and the science behind it is not yet well understood, though the genetic mutation BR1 has been identified.

Just how rare are brindle horses? What breeds produce this coat pattern? In this article, I’ll share all I’ve learned about brindle horses! Keep reading:

Horse Breeds With Brindle Coat Patterns:

The brindle pattern has been found most often on Quarter Horses and Paints. Because it was the family of Quarter Horses in which the Brindle1 mutation was found, it’s likely that this mutation is specific to certain breeds. If you are attempting to breed for this pattern, you will need a horse that has the Brindle1 mutation, and you may have the greatest chance of success in looking at these two breeds.

Wildly enough, sometimes the brindle pattern can show up spontaneously on any horse breed. Here is a list of the breeds that have documented the brindle pattern:

  • Quarter Horses
  • American Paint Horses
  • Arabians
  • Mustangs
  • Tennessee Walking Horses
  • Spanish Horses
  • Various European Warmbloods

 

The pattern has also been found in donkeys and mules.

How Rare Are Brindled Horses?

The brindle coat pattern is extremely rare in horses; some say it is the rarest coat pattern of all! I personally have never met a truly brindled horse. Because there are so few of them and the science behind them is not well understood, it can be challenging to find reliable information about this coat pattern when researching (that’s okay – I’ve done the research for you). This coat is so rare that even experienced equestrians may tell you there is no such thing as a brindled horse.

The First Record of a Brindle Horse

The first written record of a brindled horse was from a publication called Genetica. In 1942, author J.A. Lusis described a brindled Russian cab horse that was documented and photographed in the 1800s. It is believed that this horse was sent to a taxidermist upon his death and can be seen at the Zoological Museum of the Academy of Science in Saint Petersburg. If mounting and displaying a cab horse in a museum because of its color is not evidence of the rarity of this coat pattern, I’m not sure what is.

Brindle Horse Registry

In 1998, a registry was created for the brindled horse called the Brindle and Striped Equine International, or IBHA. This seems to be the only registry of its kind, though it is difficult to tell whether the registry is currently active or not (the website has been deactivated, unfortunately). Brindled horses can also usually be registered under their own breed registry, but many registries do not recognize the color “brindle.” In this case, most horses registered under a specific breed registry with this pattern are labeled as dun or another pattern, depending on the base color.

What Does A Brindle Coat Look Like On A Horse?

A brindle coat pattern will present irregular vertical stripes over a horse’s base coat. These stripes can be darker than the base color, called standard brindle, or lighter than the base color, called reverse brindle. A brindle pattern can show up over any base color. In addition to the change in pigment, brindle stripes are also different in texture than the rest of the coat – usually having hairs that are described as wiry or “unruly.” Brindle stripes are most prominent along the neck, shoulders, and hindquarters and are not usually seen on the head or legs. 

The appearance of the brindle pattern can vary depending on the base coat of the horse, with some stripes being more striking than others. A reverse brindle pattern on a light gray horse may be very subtle, while a bay with lighter stripes will be more obvious. The pigmentation can also change with the seasons, and in the Winter, the stripes may appear as simply flea-bitten. Sometimes, the different texture is the only noticeable sign of a brindle, regardless of the season. 

A brindled coat can have a unique appearance, with some describing it as looking like there is water dripping down a horse’s body. Depending on the color of the horse, I tend to think it looks like a horse that was dipped in paint and then left in the rain, with streaks of color washing off of the body in stripes. It’s really very striking!

The Genetics Of The Brindle Coat

The genetics of horse coloring and patterns are well-studied, with researchers learning about and discovering new genes and mutations every year. This means that our understanding of the science behind different coat patterns is ever-changing, and the knowledge surrounding the brindle coat pattern is no exception. What is known currently is that there are two possible avenues to a brindle coat on a horse: the Brindle1 gene and chimerism.

The Brindle1 gene can cause a brindle pattern.

In 2016, a herd of biologically related Quarter Horses was studied by a lab in Switzerland. These Quarter Horses had a unique brindle pattern, and the lab was able to identify a genetic mutation they found to be responsible. They named this mutation the Brindle1, or BR1. This mutation is heritable, and a hair sample test now exists and is available through UC Davis to determine whether a specific horse carries this mutation.

Brindle1 is semi-dominant. It is also x-linked, which means that its presentation will differ depending on whether there are two x chromosomes (meaning the horse is female) or only one x chromosome (meaning the horse is male). 

If a female has only one copy of the Brindle1 genotype, she will display the brindle coat pattern and texture; this mare has a 50% chance of passing this variant to her offspring. A female with two copies of the Brindle1 genotype will have a sparse mane and tail and will not have the brindle coat pattern or texture; this mare will pass the variant to all of her offspring.

Male horses with the Brindle1 mutation will also have a sparse mane and tail but will not display the brindle coat texture. They will pass this variant to all of their offspring. Because a male horse with the Brindle1 mutation will not show the classic brindle markings, if you see a brindled stallion or gelding, his pattern is due to another genetic condition known as chimerism.

Chimerism can cause a brindle pattern.

Chimerism is an anomaly that occurs when a horse or other animal, human, or plant has two complete genetic make-ups. This is rare and happens when two different zygotes, each genetically distinct from one another, join during the formation of one embryo.

A brindle pattern caused by chimerism then will not be passed down to offspring because the reason for the coat is that there are two completely different color phenotypes presenting on one horse, rather than a genetic mutation that can be inherited. This anomaly is considered to be “spontaneous” and, therefore, cannot be predicted or replicated in breeding. 

What Other Animals Have A Brindled Pattern?

While brindled horses are not seen very often, there are some animals on whom you’ve likely seen the pattern before. Some dog breeds are known for having this pattern; it is most commonly seen in Boxers, Greyhounds, Great Danes, and Bull Dogs. It can also be found in Shepherds, Corgis, and several Terriers and Hounds. 

The brindle pattern is also found in cats and is called “tortoiseshell.” Tortoiseshell cats are almost exclusively female, which leads me to wonder if the genetic mutation that causes the pattern may be related to the one that had been found in Quarter Horses. They can also be confused for tabby cats, which is its own striped pattern commonly found in felines. 

Brindle is also found in cattle, guinea pigs, wildebeests, and, interestingly, geckos. 

Brindle Isn’t Just For The Dogs

You may never have known that horses can be found in the brindle pattern, and you wouldn’t be unique in that. It is so very rare that many equestrians will never meet a brindled horse. I personally have never met a horse with this striking pattern, but I hope that I will be able to one day! It’s a beautiful pattern, in part because of the color contrasts but also because it is so uncommon.