How To Read Your Horse's Test Results: Temperament

January 30, 2024

If we asked you to think about the personalities of every horse you have ever met, there is little doubt you could think of at least one horse who needs to get into absolutely everything at the barn or another horse who spooks at his own shadow no matter how many times he sees it. But did you know that recent genetic studies show their tendencies toward curiosity or vigilance appear to be hard coded into their DNA? Did you know you can also test for it using a few strands of your horse’s mane or tail hair?

That’s right! Etalon Equine Genetics is here to shine a light on where your horse falls on that genetic spectrum as part of our comprehensive testing panels. Imagine the possibilities this knowledge unlocks: a peek into your horse's psyche, their predisposition towards investigating the unknown, or scrutinizing their environment. But it doesn't end there. This genetic revelation isn't merely academic - it holds practical implications. Insights from ongoing studies showcase that these genetic tendencies could influence training response and behavior, making a profound impact on the partnership between horse and rider.

Join us as we explore this groundbreaking frontier where genetics meets horsemanship, uncovering the DNA-encoded quirks that make each steed a unique and cherished companion.

Understanding the Temperament Gene DRD4

While it is widely accepted that there must be a range of genes that impact an individual’s overall personality, research has found and continues to find an association between novelty-seeking behavior, or curiosity, in a variety of human populations and natural variations in the dopamine D4 receptor (DRD4) gene. Multiple studies also found a link between aggressive behaviors in dogs and the DRD4 gene. This understanding of DRD4 led geneticists to believe that horses might also display similar associations in their temperaments. The research they conducted on 136 Thoroughbreds in Japan ultimately supported that hypothesis, finding a genetic link between curiosity versus vigilance and genotype.¹

While you may have certain ideas about vigilance and curiosity in horses, let’s quickly get on the same page when we refer to those two temperament terms. Curiosity in the horse has been defined as an interest in novel objects and a willingness to approach them. Vigilance refers to the tendency of a horse to examine its surroundings carefully and from a safer distance.

The study referenced above found that horses were more likely to be curious if they were homozygous (had two copies) for the G allele of the DRD4 gene, more likely to be vigilant if they were homozygous for the A allele, or a mixture of both curious and vigilant if they were heterozygous (having one copy of each allele). For simplicity, we will refer to the G allele as the “curiosity variant” and the A allele as the “vigilance variant” moving forward.

The DRD4 Gene and Its Influence on Temperament

While behavior, and temperament by extension, can be incredibly difficult to quantify because it is so subjective, it remains a huge reason why you may or may not get along with a certain horse. Whether you are an owner, breeder, trainer, or potential buyer, knowing a horse’s natural tendencies toward curiosity or vigilance based on their unique genetics can give you a leg up in your relationship with them.

There are three possible genotypes for the DRD4 genetic variant for temperament. Your horse’s Etalon DNA results will be one of the following possible combinations:

  • Curious = Two Curiosity variants; horse may be more curious than vigilant.
  • Curious/Vigilant = One Curiosity and one Vigilance variant; horse is likely both curious and vigilant.
  • Vigilant = Two Vigilance variants; horse may be more vigilant than curious.
A bay and white paint horse is featured next to his Etalon Equine Genetics DNA results that show he is a Curious type horse for temperament.

In an ongoing study with Etalon clientele and top trainers, differences in training response and behavior between the temperament genotypes can sometimes be startling. If you already know what you prefer in your athletic partner, this information can be especially helpful in determining whether a horse is a good match for you and/or your trainer. If you know that you like a more technical ride, a vigilant horse could be more suited to you. Whereas if you like a horse that's a bit more forgiving of its rider or its surroundings, a curious horse might be a better fit. Owners of vigilant-type Thoroughbreds and Warmbloods have also occasionally reported that their horses are more aloof.

"It's been really interesting," Dressage trainer Katie Hoefs-Martin describes. "I've been finding that horses with two curious variants tend to be more forgiving with riders who are learning or not confident or tend to be less steady whereas vigilant horses tend to be a bit more demanding of their partners and less forgiving to big mistakes. Horses with one curious and one vigilant tend to tip toward how their rider or handler works with them, like a fearful rider seems to bring the vigilant and a confident rider brings out the curious side of a horse. Knowing their genotype has helped make decisions on matching horses and riders as well as tailor their training routines to help both their horse and rider perform their best."

Dr. Samantha Brooks, associate professor at the University of Florida, joined us on our podcast, Unbridled Genetics, to talk about temperament and highlighted two real-world examples where having this information can help you make the most informed decision possible when purchasing a horse. “If you have your nine-year-old 4-H-er coming with you to look at a potential horse, wouldn’t you like to know that… they are going to be able to handle crowds and announcers and all the big noise once your kid takes this horse to states, or… that they will handle it better than others?”

“Or, let’s say you’re a professional who is looking to take an off-the-track Thoroughbred and turn it into a barrel racer. You’re going to want those quick reflexes and that hot temperament. Some of these genetic tools can help you to stack the deck a little in your favor.”

Genetic Insights for Informed Horsemanship

Genetic testing of the DRD4 gene by Etalon Equine Genetics sheds light on the fascinating connection between science and horsemanship. The revelation that curiosity and vigilance are encoded in a horse's DNA has practical implications for training, behavior, and horse-human partnerships. The focus on the DRD4 gene provides a genetic basis for understanding differences in temperament traits. Whether your horse is more curious, a mix of curious and vigilant, or predominantly vigilant, this genetic knowledge aids decisions in training and horse selection.

Dr. Samantha Brooks' examples highlight the real-world impact, from ensuring a young rider's compatibility with a horse's temperament to assisting professionals in choosing horses for specific disciplines. In essence, exploring the genetic frontier of temperament enriches our understanding of each horse's unique qualities, providing a valuable tool to enhance the bond between horse and rider.


¹ Momozawa, Y., Takeuchi, Y., Kusunose, R., Kikusui, T., & Mori, Y. (2005). Association between equine temperament and polymorphisms in dopamine D4 receptor gene. Mammalian genome: official journal of the International Mammalian Genome Society, 16(7), 538–544. https://doi.org/10.1007/s00335-005-0021-3

“The Role of Genetics in Horse Temperament and Behavior” on Genetics Unbridled - Horse DNA & Technology Powered by Etalon Equine Genetics

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