Is Your Horse Chronically Stressed?

January 4, 2024

By Sarah Griffiths, DCH

I talk a lot about nutrition on this blog but I wanted to take the time to address the subject of chronic stress in horses this week. After 3 decades with horses, I’ve seen it all (or close to it). After all I’ve experienced with my own horses and in various facets of equine sporting and management, I believe that the horse industry is in need of major renovation when it comes to ethics. I’d like to contribute to changing the paradigm of horse care in today’s article.

My understanding of animal health comes from a process that is a little bit backwards. I use a reverse engineer way of thinking to figure out what makes animals sick instead of just looking at disease as a random or genetic event. To understand disease development, I have dedicated years of study to the ancestry of companion species and the most common modern disease processes that affect them. I research the science that suggests the causes of each disease and compare that to their ancestry. This process reveals valuable clues about where we might have gone wrong and how we might change direction.

To understand stress in horses from a scientific perspective, we can explore factors that increase the stress hormones cortisol and adrenaline and increase serum inflammatory immune markers. The most common equine diseases all have epigenetic (environmental) components to them. Environmental stress comes in many forms for modern horses including housing, footing, bedding, diet, exercise, climate, training techniques and more.

My priorities with my own horses have changed dramatically over the years. The focus has become entirely on their quality of life and very little on my personal equestrian goals. I’ve realized the stress that our human expectations can have on horses and have humbly changed my trajectory for what I want to accomplish in my partnerships with them. What I’ve learned is that there are many ways a horse can experience stress on physical and emotional levels. It is entirely our responsibility to create happy lives for them if we choose to have them in ours. For us to do that, we need to take a hard look at our own capacity for self-awareness, humility, our reasons for having horses and our level of empathy towards them.

This week, let’s talk about how to improve your horses’ quality of life by reducing stress.


Which chronic diseases are the most prevalent in horses today?

  • Digestive disorders: Colic, ulcers, hind gut acidosis, fecal water syndrome
  • Insulin resistance, Cushing’s disease and laminitis
  • Inflammatory conditions eg. chronic injury, asthma and arthritis

Exploration of the research surrounding these diseases helps us to understand the causes – and stress is at the top of the list. Physical and emotional stress have been scientifically proven to change metabolism and increase immune-mediated inflammatory markers in the blood. Horses need us to do better. Below are some significant ways for us to do that.



Nutritional stress comes in 5 major forms for horses:

a) nutritional deficiency

b) toxic feed by-products

c) lack of access to varied fibre

d) excess dietary starch (sugar)

e) microbiome disorders



Do you know what’s in your hay? Most people literally have no idea. To determine if your horse has any nutritional deficiencies, it’s best to use a multi-faceted approach to identify problems. First, get a hay analysis from your supplier to get a baseline on the nutritional value of your forage source. If you’re not sure how to read a hay analysis, you can check out my article here for help.


It is also helpful to have blood testing done to explore your horse’s mineral levels and, if there are any specific health concerns, vitamin testing may also apply. You can ask your veterinarian to run these tests for you. Mineral testing is inexpensive and well-worth it. I recommend doing it once a year as a part of a preventative wellness check. Once you have your horse’s results, you can supplement as needed instead of guessing what might be missing. If you’re not sure what supplementation is best, work with a professional.


Highly processed feeds wreaks digestive havoc on horses. Research shows that high starch diets drastically alter the gut microbiome of horses and causes higher production of valeric acid (1) which is a contributor to ulcer formation (2). Highly processed feeds of any type should be avoided for prevention of gut disease in horses. It is well-documented that gut imbalances are a catalyst for systemic inflammatory diseases and metabolic dysregulation.

Processed feeds also contain crops from the conventional agriculture industry (genetically modified crops) that are sprayed heavily with herbicides and pesticides including glyphosate, dicamba and more. Glyphosate is a proven metabolic deregulator, a patented antibiotic and a cancer-causing agent. The top GMO crops fed to horses are: wheat, corn, soy, sugar beets and alfalfa.

The grains, legumes and by-products used in equine and livestock feeds are of lower quality than those used for human consumption. They house aflatoxins which are a chemical by-product of dangerous mould formation on improperly cured crops. Aflatoxins are poisonous to horses and can result in liver damage and inflammatory disease (3).


Lack of fibre in the equine diet is probably one of the most under-rated issues in the equine health field. I personally believe that the current recommendations for equine dietary fibre are grossly underestimated which can be reflected in the number of horses suffering from digestive and metabolic disease. Providing and abundance and variety of healthy fibre sources to your horse requires more than just adding a processed feed that says that it has fibre in it! Fibre comes in many forms in the ancestral equine diet from mature grasses to bark to herbs and roots. Fibre sources also vary throughout the seasons. The less access to varied fibre, the more risk of metabolic dysregulation (4) and inflammatory disease (5).

Inadequate dietary fibre increases the effect of starch on blood sugar levels and insulin balance. That’s why it’s so important to consider the fibre and starch in relation to each other and not by the terms “high fibre” and “low starch.”


Physical pain is another significant problem for modern horses. There are endless ways that horses can experience physical stress:

  • lack of bedding, leading to poor sleep quality and body soreness
  • poor footing: wet, slippery, hard or rough ground
  • excessive exercise and repetitive movement
  • unresolved inflammation or illness
  • injury
  • poor farriery
  • stagnation of movement
  • surgery and medications


Be honest in terms of how your horse is feeling in this area. If you see places that need improvement, do it. Be sure your horse is physically comfortable. If you think something doesn’t feel or look right, listen to yourself. Listen to you horse. No matter how much it costs now, it will not compare to what it will cost you in both stress and money later if you ignore it.

  • Provide soft, deep bedding for your horse to sleep on and keep the dust down
  • Assess the footing in living spaces
  • Assess your horse’s fitness level and don’t push them over their threshold
  • Make exercise varied and appropriate for your horses’ experience level and age
  • Listen when your horse is saying no to something – this is important information – and DON’T assume they are just being “bad”
  • Tend to injuries immediately and give as much time as possible for full recovery
  • Be sure that your farrier is balancing your horse’s feet correctly. Get x-rays if you aren’t sure
  • Get your horse moving as much as possible to increase blood flow and oxygenation to all the body tissues.
  • Have regular bodywork done on your horse and or other therapies such as red light
  • Be minimal when it comes to medications wherever possible, especially with vaccines, NSAID and antibiotic drugs. These medications all come with risks of increasing systemic tissue inflammation and damage


In order to understand what stresses horses out, it requires us to use our intuitive and empathic abilities to see life from their point of view. We also need to regard them as sentient beings that have complex emotions. Research shows that the following factors can be highly stressful for horses and can affect their immune system, gastrointestinal system and metabolic function:

  • trailering (6) (7) (8)
  • sporting (9) (10) (11) (12)
  • housing in small areas (13) (14) (15)

It’s also important to go beyond scientific studies and see the horse that is in front of us. Tune into your horse and listen to what they need. Signs your horse might be emotionally stressed:

  • Chronic behavioural issues (spooking, bucking, rearing, kicking, biting, etc.)
  • Sudden changes in behaviour
  • New environments or change to the environment
  • Social stress (eg. bullying between herd members, herd-bound behaviour or lack of social time)
  • If you’re stressed, take note. Our stress affects our horses too! Check out the video on the research being conducted at the Heartmath Institute on this very subject by following this link.


  • Practice trailering with your horse with small sessions on a regular basis not just before you have to take them somewhere. If you know your horse has stress with loading or traveling, do the work to get them comfortable with this process. It can literally be life-saving.
  • Be kind in training. Assess your horse’s fitness level and stress thresholds. Adjust training to a small daily challenge rather that rigorous and repetitive training. Less is more! Vary your training lessons and spend time grazing your horse, doing groundwork and hacking out on trails.
  • Do not give your horse challenges that they cannot meet. It will erode your relationship and their trust in you. Break things up in to learnable pieces and make it fun and easy for them to learn.
  • Build your relationship with your horse so they are tuned into you and trust you in stressful situations. Ensure that you are clear on safe and healthy boundaries so your horse knows clearly what is being asked of him. If you’re unclear with your communication, it can be very stressful for your horse.
  • Address any negative stress-related behaviours with a professional if you can’t handle them yourself
  • If your horse is finding something mentally challenging, pay attention. Slow down and figure out what they need.
  • Give your horse as much space as possible to promote movement
  • Figure out a social situation that works for your horse so they can have interactions with other horses and long term equine relationships
  • If you plan on moving your horse to a new location or a horse show, prep for stress reduction. Nutrients like magnesium, vitamin B comlex, C and E are indicated for reducing stress
  • Provide as much turnout or grazing time as you can. Don’t bubble wrap your horse! Even top level equestrians like British dressage trainer Carl Hester recognize the necessity of turnout and social time for horses.
  • Spend quality time with your horse. Make time to enjoy each other without pressure and expectations.
  • Practice self-awareness to ensure that your emotional stress is not affecting your relationship with your horse. Accountability is important and so is your mental health!


Did you know that the gut and brain share an axis in the body? Were you aware that poor gut health can affect the nervous system and lead to increased anxiety and depression in multiple species, including horses? (16) It can also lead to colic and laminitis. (17)

Factors that influence gut health include:

  • diet – high starch, low fibre (16)
  • sporting (16)
  • overstocking of living spaces (16)
  • stagnation (lack of movement)
  • medications (eg. NSAIDs and antibiotics) (18) (19)
  • chronic emotional stress
  • sterile/pathogenic eating surfaces


  • Be meticulous about assessing your horse’s diet, especially fibre and starch levels
  • Provide a multi-strain, species-appropriate probiotic
  • Provide as many prebiotic fibres as possible
  • If your horse has a history of ulcers, consider gut-reparative herbs including marshmallow, chicory and liquorice root
  • Ensure that your horse is eating during ALL of his waking hours. Lack of forage intake can lead to acid-buildup and gastric ulcer formation, especially when exercising on an empty stomach.
  • Ensure your horse is moving around as much as possible, not just with exercise but also during low-impact foraging and social behaviours
  • Avoid antibiotics whenever possible – only use when benefits outweigh the risk to the gut.
  • Avoid NSAID drugs wherever possible – they are well-document to promote ulcer formation
  • Provide clean eating surfaces for horses to eat from and, surfaces with living dirt, trees and shrubs for healthy environmental bacteria access


As we all know, sleep is imperative for regenerating our entire body, supporting the nervous system and reducing stress. Lack of sleep is a serious concern for modern horses who are living in synthetic environments. Sleep deprivation increases the stress hormone cortisol (13) and increases risk for anxiety, depression, cardiovascular and metabolic diseases (20)

Factors that affect sleep:

  • inadequate bedding
  • chronic pain
  • environmental discomfort eg. noise, light exposure
  • perceived danger
  • lack of exercise


  • Bedding quality and quantity drastically changes a horse’s sleeping behaviour so make sure you’re taking this seriously (21) (20)
  • Address chronic pain – take measures to get them comfortable. There are many natural solutions to chronic pain as well as conventional pain management if it is warranted for quality of life
  • Ensure that your horse’s evenings and nights are quiet and non-disruptive after the lights go out
  • Assess whether or not your horse feels safe in their environment as this can seriously affect their ability to have proper REM sleep
  • Adequate natural light is a must in your horse’s sleeping area so their circadian rhythm can sync with daylight hours
  • Ensure your horse has adequate space to roam when you are not there. One hour of exercise/work per day with a tiny paddock and no social time with other horses is not enough for a horse to feel tired and settled at the end of each day.

Please take these suggestions seriously! Be an advocate for the changes needed to make the lives of horses better.


  1. BMC Veterinary Research: A high-starch vs. high-fibre diet: effects on the gut environment of the different intestinal compartments of the horse digestive tract, 2022
  2. American Journal of Veterinary Research: Effects of hydrochloric, valeric, and other volatile fatty acids on the pathogenesis of ulcers in the non-glandular portion of the stomach of horses, 2003
  3. The Veterinary Journal: Toxicological effects of aflatoxins in horses, 2011
  4. Horse Production: Carbohydrate metabolism and metabolic disorders in horses, 2009
  5. BMC Veterinary Research: Gut health of horses: effects of high fibre vs. high starch diet on histological and morphometrical parameters, 2022
  6. Nature: Inflammatory-like status and acute stress response in horses after road transport, 2023
  7. Journal of Animal Science: Effect of transport on fecal bacterial communities and fermentative activities in horses: Impact of S. cerevisiae CNCM I – 1077 supplementation, 2013
  8. Research in Veterinary Science: Effect of transportation on the sympatho-adrenal system responses in horses, 2019
  9. Animal Physiology and Animal Nutrition: Effects of competition on acute phase proteins and lymphocyte subpopulations – oxidative stress markers in eventing horses, 2015
  10. Vetrinar: Indicators of exhaustion and stress markers in endurance horses, 2021
  11. Department of Large Animal Diseases and Clinic: Intense leisure exploitation influences on horses hormonal reaction – preliminary study, 2022
  12. Journal of Equine Veterinary Science: Relationship of some oxidative stress biomarkers in jumper horses after regular training program, 2016
  13. Animals: Do you think I am living well? A four-season hair cortisol analysis on leisure horses in different housing and management conditions, 2021
  14. Applied Animal Behaviour Science: Behavioural and physiological responses of horses to initial training: the comparison between pastured versus stalled horses, 2022
  15. Equine Veterinary Journal: Comparison of bone mineral content and biochemical markers of bone metabolism in stall vs. pasture-reared horses, 2010
  16. The Horse: Horse behaviour and the microbiome: what’s the connection? 2023
  17. Journal of Equine Veterinary Science: Factors influencing equine gut microbiota: current knowledge, 2020
  18. Journal of Equine Veterinary Science: Prognostic significance of oxidative stress markers in colitis associated with Phenylbutazone administration in draft horses, 2012
  19. Texas A&M University Libraries: The equine fecal microbiome – effects of diet, antimicrobials and colitis, 2020
  20. Frontiers in Veterinary Science: A review of equine sleep: implications for equine welfare, 2022
  21. British Society of Animal Science: The effects of night light and bedding depth on equine sleep duration and memory consolidation, 2020