Horse Illustrated Magazine

We have all seen the behaviors that are commonly associated with “hot” horses: the endless energy they have running and playing out in pastures, the overexcitability they have under saddle and even the jittery anxiousness they maintain in cross-ties and stalls. One of the first things to take the blame are individual feed ingredients that are thought to influence a horse’s get up and go. Nutritionist Anna Pesta, Ph.D., explains that what could be making a horse tense or “hot” is often related or tied into a variety of other factors than just nutrition, such as gastric discomfort, saddle fit, rider skill set, training and countless other possibilities. Let’s take a look at what ingredients and supplements can help in calming a “hot” horse.

Bad Reputations

“Ingredients like oats, barley, corn, alfalfa hay and molasses have been blamed for causing high-strung horses mostly due to their high starch, sugar and caloric elements,” Pesta says.

“These generalizations aren’t necessary backed by any specific testing or science, but it’s true that some horses may have more focus or calmer tendencies when fed different fuel sources. However, energy level often has a lot more to do with the total calorie intake than the nutritional makeup of those calories.”

Equine nutritionist Natalie Sullivan, M.S., PAS, owner of On Course Equine Nutrition, states that calming ingredients fall into the behavior-modifying category, which comes with a high dose of skepticism.

“The placebo effect inside the horse-human connection is incredibly strong,” she says, meaning that owners see a difference because they want to and have spent money on a product. She recently researched calming nutrition and the connection between ingredients and their behavior-modifying aspects.

“I had to infer much from human use of these ingredients, as there is very little to no research data on these common calming ingredients in horses,” says Sullivan.

Calming Ingredients in Supplements for Your Horse

The following is a look at the most common ingredients found in horse supplements that claim calming properties.

Tryptophan: An amino acid commonly found in meat and dairy that is a precursor to serotonin, a neurotransmitter found in the body that is related to mood. A paper published in the Equine Veterinary Journal in 2008 showed no behavior changes caused by high levels of tryptophan through a blood test. Another review by Applied Animal Behavior Science in 2017 showed no effect on a startle test, and found an increase in excitability for some horses.

Valerian: An herb used for insomnia and anxiety in humans. Not recommended to take for more than four weeks (WebMD, June 2022).

Raspberry leaf: Found in mare supplements claiming to help control female hormones. Very little was found about its efficacy.

Magnesium: The most popular ingredient in today’s calming supplements. Sources and quantity of magnesium vary greatly, from 200 mg to 10,000 mg per serving. A study done in 2017 in Australia concluded that there could be some reaction speed decrease in horses fed supplemental magnesium over the National Research Council’s Nutrient Requirements of Horses recommendations.

“As long as it isn’t detrimental to the overall nutrient balance, I generally tell owners they can experiment with various supplements if they like, since it is more a matter of trial and error to find something that seems to work for an individual horse,” says Pesta. “Most owners would be better served to spend their money on seeking help from a veterinarian or professional trainer rather than reaching for a supplement to quiet their horse, or spend their time trying to pin down a certain ingredient that has made their horse excitable and set out on a quest to find a feed without it.”

The Bigger Picture

It’s important to step back and look at the bigger picture if your horse seems too hot, anxious, or over-excitable.

Invest in safe pasture turnout for your horse, clear expectations for his training and performance, clean water, a salt block, quality hay and feed, and top-notch medical care. With those in place, you may just be pleasantly surprised with how well your horse can retain a healthy body, positive mindset and settled demeanor.

This article about nutrition for calming a horse, including supplements and ingredients, appeared in the September 2022 issue of Horse Illustrated magazine. Click here to subscribe!