A hyperactive horse is commonly referred to as a “hot” horse. You may know the feeling of dealing with a hot horse all too well: it can feel like your horse is going to explode at any moment.

Hot horse behaviour is associated with changes in stress hormones. Cortisol is a stress hormones that has a cascading effect on the horse’s body. [1][2][3] Chronically elevated cortisol levels in horses are associated with ulcers, colic, and impaired immune function. [4][5][6]

Hyperactive behaviour can manifest as:

  • Overreacting to new stimuli
  • Nervousness and anxiety
  • Bucking
  • Bolting
  • Rearing while on the ground or under saddle

This unwelcome behaviour is dangerous to both horse and owner, creating fear and tension. In some cases, an owner might choose to sell their horse if the behaviour becomes too much for them to handle.

Luckily, there are strategies that can be implemented to help manage hot horses. The first step is to ensure your horse has a well-balanced diet with the right amounts of energy, vitamins, and minerals.

It is also important to manage your horse’s daily routine and exercise regimen. Enabling their natural species-appropriate behaviours and minimizing boredom and frustration can also have a calming effect on some horses.

You can submit your horse’s information online and our equine nutritionists can help identify changes to your horse’s nutritional management that can promote calm behaviour.

Why is my Horse Hot?

Wondering why your horse is displaying hyperactive behaviour? It may just be your horse’s personality: hot-blooded breeds such as Thoroughbreds and Arabs are known to be more reactive than others.

However, if your horse is uncharacteristically hypersensitive then a multitude of factors may come into play.

These factors can range from nutrition, training, inhibition of natural behaviours, and environmental pressures.

1) Feeding excess energy

Your horse’s daily calorie requirement is specific to its age, weight, exercise level, and life stage. Caloric energy is required to maintain bodily processes and fuel your horse’s daily activities.

Forage and pasture should provide the majority of energy in your horse’s diet. Having too much of a good thing can lead to your horse’s diet exceeding its energy needs.

Horses can easily get too much energy when on high-sugar grasses in the Spring and Autumn. High-quality hays can also provide excess caloric energy and horses on high-grain diets often over-consume calories.

When energy intake exceeds requirements, the excess calories will be deposited as fat or expended through unwanted behaviour.

2) Feeding “Hot” Feeds

Some feeds are considered “hot” because they increase the likelihood of your horse displaying hyperactive behaviour.

Hot feeds contain ingredients that spike blood sugar levels. These are sometimes referred to as high-glycemic feeds because the sugars in these feeds are metabolized quickly and lead to a rapid increase in insulin secretion.

“Hot” feeds generally contain higher levels of sugar and starch, collectively referred to as non-structural carbohydrates (NSC).

NSC is a measure of the sugars found within plant cells. These sugars are readily digested and absorbed in the small intestine, resulting in a rapid increase in circulating sugar in the blood (serum blood glucose levels). [7]

Common hot feeds include grains such as wheat, corn, and barley, as well as commercial feeds, sweet feeds, molasses and other sugar sources.

Energy-dense feeds like plant oil or alfalfa are sometimes mistaken as hot feeds. While these feeds are energy-dense, they do not affect blood sugar to the same extent as high glycemic feeds like grain. [8]

Fat and fibre are metabolized slowly and do not spike your horse’s blood sugar levels. These cool energy sources can decrease stress and spooking compared to high starch and sugar feeds. [9]

3) Forage Composition

Forage selection can play a major role in causing your horse to become hot. The sugar and NSC composition varies for different sources of pasture and different hays.

Cool-season grasses such as timothy, brome, fescue and orchardgrass tend to have higher NSC levels. These grasses can also accumulate fructans – a type of sugar.

In contrast, warm-season grasses such as bermudagrass generally have lower NSC levels and accumulate more starch than sugars. [20]

Horses grazing on high NSC pasture and hay are at higher risk of metabolic concerns, laminitis, and reactive behaviour.

It is recommended to get a hay analysis to help you select the right forage for your horse.

Growing Conditions and NSC Levels

Sugar levels also vary depending on growth, management, and harvesting conditions. Stress conditions such as drought and over-grazing can cause sugars to accumulate in pasture. [10]

Cold climate grasses have evolved to produce more NSC when stressed by cold temperatures so they have a better chance at surviving winter.

During drought conditions, grasses will increase their NSC production to ensure they have ample energy for a quick growth spurt when the rain returns. [11]

Overgrazing also causes the grass plant to experience stress because its photosynthetic food production is limited by leaf removal. The grass responds by trying to store as much energy as possible to grow when grazing pressures ease. The result is higher NSC grass.

4) Vitamin and Mineral Deficiencies

Nutritional imbalances in your horse’s diet can also affect their behaviour. If certain vitamins and minerals are not supplied in adequate amounts or if the ratios of these nutrients are out of balance, hot behaviour may occur.

In our analysis of thousands of equine diets, most have deficiencies in one or more vitamins and minerals which could contribute to anxious behaviours. Feeding a well-balanced mineral and vitamin supplement can help to correct for common deficiencies.


Magnesium plays an important role in muscle contraction, metabolism, and electrolyte balance. [12] Magnesium is also important for neurological function and mood balance.

Deficiency in this mineral can result in nervousness in the horse. A magnesium-deficient horse may exhibit excitability, anxiety, irritability, muscle pain or tremors, and sensitivity to sound. [13][14]

Supplementing with magnesium may have a calming effect if your horse is deficient. However, supplementation is unlikely to have a calming effect if your horse already obtains adequate amounts of this mineral from the diet.

Excess magnesium is readily excreted in the urine and not stored in the body. For this reason, we recommend submitting your horse’s diet for analysis first so a nutritionist can review magnesium levels in your feed and forage.

B-Complex Vitamins

B-vitamins can also play a role in keeping your horse calm. Both Vitamin B1 (thiamin) and vitamin B2 (riboflavin) contribute to nervous system function and mood regulation.

Clinical thiamin or riboflavin deficiencies are very rare in horses because these B-vitamins can be manufactured by the bacteria in your horse’s gut. [15]

However, B-vitamin production in your horse’s gut can be compromised in young, old, ill or stressed horses. These horses might benefit from additional B-vitamins in the diet to help modulate their behaviour.


is an amino acid that is a precursor to the production of the “happiness” hormone, serotonin. Tryptophan is also famously associated with making humans feel sleepy after a Thanksgiving turkey dinner

Many equine calming supplements contain tryptophan as the primary active ingredient. However, deficiency in horses has not been observed and research into supplementation has not demonstrated efficacy for promoting a calming response in horses. [16][17]

5) Mycotoxin Contamination in the Feed

Most horse owners associate mouldy hay with respiratory problems, but the toxins from mould called mycotoxins can make some horses hypersensitive. [16]

In severe cases of mycotoxin exposure, horses may display hypersensitivity to movement and noise. [17] Further studies are needed to understand the prevalence of mycotoxin-induced hypersensitivity in non-clinical presentation.

6) Pain

Pain can also cause increased reactivity and sensitivity in horses. The source of pain is often difficult to pinpoint in your horse; potential causes include abdominal discomfort due to digestive ailments or general irritation due to allergies.

Gastric ulcers are very common, particularly in exercising horses or horses fed high-grain diets.

Ulcers can contribute to stress and hot behaviour. Conversely, hot behaviour can cause stress and ulcers which can make it difficult to identify the root cause of the problem.

Adopting strategies that minimize the risk of ulcers can have a positive impact on your horse’s behaviour.


Quiz: Assess Your Horse's Ulcer Risk

PSSM and Tying Up

Muscle disorders like polysaccharide storage myopathy (PSSM) and exertional rhabdomyolysis (tying-up) also cause pain and reactive behaviour.

PSSM horses have a genetic mutation that causes a buildup of sugars in muscle tissue. Horses that tie-up are affected by calcium dysregulation in their cells, resulting in muscle tremors. [18][19][20]

Both disorders can contribute to muscle pain, ranging in severity from subtle discomfort to noticeable pain. If you notice a change in your horse, it is best to speak with your veterinarian.

Higher levels of Vitamin E are recommended to combat increased oxidative stress from muscle spasms caused by both of these disorders. PSSM horses also require lower levels of NSC and higher fat in their diet.

You know your horse better than anyone else. Recognizing what their normal movement feels and looks like can help you distinguish if they are acting up due to pain or if they are feeling their oats.

7) Inhibiting Natural Behaviours

Hot behaviour is sometimes a result of domestication practices and stabling conditions. Horses are naturally social animals and have a high drive to forage.

Our modern management practices may inhibit the expression of some of their natural species-appropriate behaviours. Stall confinement can impede your horse’s evolutionary drive to walk and graze for upwards of 16 hours per day.

When horses are not allowed to express normal foraging behaviours, this can result in excessive energy, pain from gastrointestinal disturbances, boredom, and frustration.

Feeding Practices

Horses that are stabled are typically fed in several large meals during the day. This disrupts the continuous slow grazing behaviour that the horse’s body and mind have evolved to exhibit.

Meal feeding also has negative implications for gastrointestinal health as well as mental stimulation. Horses that go for long periods of time between meals are at greater risk of gastric ulcers because there is nothing in the stomach to buffer against gastric acids. Meals that contain high quantities of starch also increase the risk of hindgut acidosis.

Providing your horse with lots of turnout and feeding a forage-first diet can help to support a species-appropriate lifestyle.

If your horse is stabled, using a slow-feed hay net is a straightforward way to mirror their natural behaviours. Hay nets are associated with reduced stereotypic behaviours (cribbing, weaving, etc.), increasing time spent eating, and a friendlier disposition. [18]

Feeding hay free-choice may seem like a more natural alternative, but actually presents several disadvantages compared to feeding with a hay net. When hay is offered free-choice, horses tend to eat their required intake quickly and spoil the remaining hay. This does not mimic the natural grazing behaviour we are looking for and can have unintended consequences on digestive health.


Horses are herd animals and generally display lower stress levels when kept in a consistent social group.

Individual turnout and stabling are in direct conflict with their herd mentality. Whenever possible, give your horse contact with one other horse. [19]

Stress-associated hot behaviour is often seen in horses that are isolated. This hyperreactive vigilance is natural for prey animals because they must be aware of potential threats.

Understanding your horse’s evolutionary needs and species-appropriate lifestyle can help to mitigate unwanted behaviour.

8) Exercise and Fitness

Hot behaviour may also occur if your horse is in excellent physical condition and no longer finds its workload challenging. Increasing the intensity, duration or complexity of your horse’s work may help.

Exercise supports normal blood sugar metabolism; when your horse exercises, glucose is taken up from the blood by muscles to fuel work. You can reduce excess energy in your horse’s diet by exercising them regularly. [11]

9) Your Relationship and Training

Your relationship with your horse is an important factor for maintaining calm behaviour.

Unclear training can cause frustration and confusion which may appear as hot, unruly behaviour. In contrast, proper training can create trust and reduce hyperactivity.

Exposing your horse to novel objects, places, people, and animals can desensitize them and reduce spooking.

Feeding for Calm Behaviour

There are several key principles that horse owners should follow when feeding their horses to support calm behaviour.

1. Feeding a forage-first diet:

Feed 1.5 – 2.5% of your horse’s bodyweight in forage every day as the major component of your horse’s diet. Hay and pasture will support your horse’s digestive comfort and satisfy their need to express foraging behaviour.

In one study, horses that were fed a high fibre diet had higher serotonin levels compared to horses on a high starch diet. Fiber not only promotes hindgut health, but also supports healthy hormone levels. [26]

2. Feeding a balanced diet:

Ensure your horse’s diet is providing adequate levels of essential vitamins, minerals, and macronutrients.

Nutritional balance is critical for managing your horses’ mood and behaviour. If your horse needs additional minerals and vitamins in their diet, use a concentrated mineral and vitamin supplement instead of a complete feed or ration balancer.

Both complete feeds and ration balancers contain nutritional fillers and are designed to be fed at a high feeding rate to meet your horse’s daily requirements. This can add excess energy to your horse’s diet.

In contrast, Mad Barn’s Omneity Premix mineral and vitamin is fed at a rate of 120 grams per day for a 500 kg horse and does not add excess caloric energy. This can help to minimize mood disturbances.

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3. Weighing supplemental feeds:

It is easy to over- or under-feed key nutrients like vitamins and minerals if you are not weighing your horse’s feed. Complete feeds and ration balancers are also frequently fed at an incorrect rate.

It is important to know exactly how much of a specific product you are supposed to feed and how much your horse is consuming on a daily basis.

Scoops and measuring cups can make feeding more convenient but are imprecise. Instead, nutritionists recommend measuring the amount of each feed you are giving your horse on a daily basis. Use a kitchen scale to get an accurate measurement.

4. Using fat for energy:

Instead of using “hot” commercial feeds or grains as an energy source for your horse, consider cool energy sources such as plant-based oils.

Fats like flax seed, camelina oil, or Mad Barn’s w-3 Oil, are metabolized slowly and will not spike your horse’s blood sugar levels. Fat supplies twice as many calories per gram when compared to protein and carbohydrates.

5. Carefully selecting grains:

In general, you should avoid commercial feeds and grains and stick with high-quality forages and fat for energy.

However, if you need to use grains to meet your horse’s nutritional requirements, select a processed feed to ensure full digestion in the small intestine. Heat, steam, and mechanical processing are all methods to increase the digestibility of your horse’s feed.

It may seem counterintuitive to use a processed feed, but this prevents undigested starches and sugars from entering the hindgut, which can cause dysbiosis and hindgut acidosis. [27].

You should also feed grains in multiple small meals throughout the day and avoid individual meals with high quantities of starch.

6. Supporting natural equine behaviours:

Use a slow feed hay net to increase the time your horse spends foraging. This will keep them mentally stimulated and limit the amount of time they spend with an empty stomach.

By slowing down the consumption of your horse’s daily hay ration, a hay net keeps the horse chewing for longer periods of the day. This increases saliva production, helping to consistently buffer stomach acid and reducing the risk of gastric ulceration.

7. Feeding to their activity needs:

Feed your horse according to their activity level and closely monitor changes in their body condition.

Pleasure horses usually need to be fed based on a maintenance or light workload. Performance horses need to be fed based on a moderate to heavy workload.

Examples of moderate work include mid-level eventing with weekend events, dressage and most show jumping. Heavy work includes endurance, racing thoroughbreds and upper-level eventing.

8. Turnout during the early morning:

Adequate turnout is important for your horse’s overall health and well-being. However, turnout on sugar-rich pasture can be a problem for many horses.

To reduce your horse’s NSC intake, only provide pasture accesses between 3 – 10 AM when sugar levels are lower. This is especially important when your pasture may be stressed: during the hot months of the summer, a cold snap, drought, or over-grazing.

9. Feed mould-free hay:

Never feed your horse hay that has signs of mould growth. Mycotoxins are more prevalent in hay and pasture during cool and wet seasons like spring and fall. [28]

Storage practices can help to reduce the risk of hay going mouldy. Make sure hay is adequately dried before storing indoors. Ideally, keep hay in a moisture-free environment and stack hay bales to enable evaporation of moisture content.

10. Supplementation:

Mood supplements for horses are sometimes the first thing that horse owners look to when dealing with a hot horse. However, we recommend implementing the strategies listed above first before adding a new supplement to your horses’ diet.

There is limited successful research on calming supplements in horses, but some ingredients have anecdotal support for efficacy.

Ingredients such as inositol, valerian root, tryptophan, chamomile, taurine and ashwagandha are purported to promote a calm mood. These ingredients have some demonstrated efficacy in human studies, but require further research in horses to determine whether they work and how they should be used.

We recommend consulting with a nutritionist first to evaluate your horse’s overall feeding program before researching calming supplements to use.

Is Your Horse's Diet Missing Anything?

Identify gaps in your horse's nutrition program to optimize their well-being.


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