When someone mentions a specific horse breed or coat color, we might expect certain behavioral traits or personality quirks, but which of these are based in fact?

“As horse people, we’ve given (horses) breed stereotypes that note trends in inherited behavioral tendencies in different gene pools,” says Samantha Brooks, PhD, associate professor of equine physiology at the University of Florida, in Gainesville. “Arabians, for example, have the reputation of being reactive, ponies as mischievous, while stock horses are known to be calm. We are only just beginning to study how much, and in what way, genetics influences behaviors that are important to the well-being (and economic value) of horses.”

Genetics can influence behavior in all animals, but environmental factors also play a role in a horse’s behavior. “To the best of my knowledge, while there have been only a few genetic studies focusing on behavior genetics of horses, additional studies are still needed to really understand how genetics influence behavior in these animals,” says Liza C. Gershony, DVM, PhD, community engagement and outreach coordinator for the Veterinary Genetics Laboratory at the University of California, Davis.

Horse Coat Color Stereotypes 

Some horse owners believe that horses of certain colors might be more likely to have various personality traits, although many of these stereotypes are not evidence-based. Chestnuts, for example, have a reputation for being “hot” and reactive when compared to horses of other coat colors. “There appears to be anecdotal evidence that associates coat color with behavior, and I would not be surprised if there were connections between the two,” Gershony says.

Brooks has found that in studies of Tennessee Walking Horses, black mares were perceived to be less friendly than other coat colors. “Based on the biochemical pathways used both for pigmentation and for pain sensation, there is a number of studies from other species showing that individuals with variants of the MC1R gene (responsible for redheads in both people and horses) have stronger sensations of pain and receive less relief from analgesic drugs. We’ll have to wait and see if studies prove the same effect is present in horses, but if it is, it might explain why we perceive chestnuts as flightier. They are reacting more strongly to pain or possibly have a greater fear of potentially painful situations.”

The behaviors some horses exhibit might be secondary to issues caused by a coat-color-related genetic disorder. “For example, gray horses are prone to melanoma, although the genetic cause of melanoma in gray horses is not yet known,” says Gershony. “The Appaloosa’s spotting is associated with night blindness and increased risk for recurring uveitis.” These horses might react in a way that can be confused for “bad behavior” when they are in pain or uncomfortable.

Genetic Testing for Equine Behaviors

This begs the question of what behaviors are known to stem from genetics, and can they be completely controlled by training and management? Which behaviors can be altered, and which can’t?

“Subconscious reflexes, in humans and horses, are less influenced by learned patterns of behavior (gained through training and experience) and can have a strong influence from genetics,” says Gershony. “The startle response, for example, experienced by horse people as spooking, may have a component that is inherited.”

The most primal of instincts also seems to be a factor in a horse’s genetically influenced response. “Fear is probably a behavior that stems from genetics and cannot be completely controlled by training and management,” she adds. “However, (fear behaviors) can be altered to an extent by learned experiences.”

Owners and breeders can have genetic testing done on young horses to identify those that are likely to be reactive, says Brooks. Genetic testing is sometimes offered through breed organizations and some universities with veterinary programs. This information can help with decision making such as who should train the horse, how much time to spend training, and the type of training used to reduce reactivity; however, reactivity cannot be completely eliminated. For example, says Brooks, “if you are looking for a 2-year-old to be a futurity project for a youth rider, you might select the young horse that has a genetic predisposition to be more stoic. It’s not a guarantee, since there’s always exceptional circumstances, but being able to know just that little bit more about what the future holds for a young horse can make all the difference in setting them on the right path for success.”

The safety of both horse and rider also comes into question with more severe genetically influenced behaviors. “Overtly aggressive or excessively fearful and reactive horses are dangerous to those around them—both humans and other horses,” says Brooks. 

Owners and trainers should take note of subtle behaviors and the horse’s temperament, which can indicate future behavioral problems. “We all know of horses that showed great athletic promise but just couldn’t reach their potential due to behavioral issues,” says Brooks. “Conversely, many of us have also known a horse with lameness or other health challenges that we’ve kept going only because they had exceptional kindness and heart. Genetic testing could provide one more tool to help mitigate risk for unwanted behaviors and help to encourage management practices (such as adjustments in turnout schedules or training methods) to promote valuable behaviors.”

Take-Home Message

Understanding the role genetics plays in a horse’s behavior can help owners make educated decisions regarding their horse’s training and management. While some studies exist regarding horse coat color and behavior, our sources say owners should ask their veterinarians about genetic testing to better understand their horses’ potential behavioral problems. Brooks said she hopes future research funding will provide further answers about how genetics influences horses’ behavior.