Non-Compassionate Sources
We at The Open Sanctuary Project disavow animal experimentation and any “use” of animals for human purposes. Because compassionate works on valuing the personality, intelligence, and unique attributes of many nonhuman animals are rare, in this resource, we draw from existing work that may be non-compassionate in nature, but which may all the same be used to improve the lives of residents. We work towards a future when compassionate, non-exploitive, and non-invasive research is the norm, but in the meantime, we will work with what we have to help sanctuaries help animals as effectively as possible. You can read a little bit more about our non-compassionate source policy here.

Lavender Aromatherapy: It’s Promising

If you care for horses, you may find yourself trying to reduce the stress horse residents experience during health checks, hoof trimmings, transport, or other situations that commonly cause anxiety. There are a number of ways this can be approached, depending on the situation, the species, and the individual. One thing that may come up in your research is using certain specifically scented essential oils (aromatherapy) to reduce stress. Lavender is a scent frequently associated with calming properties and physiological effects in humans, and there is quite a bit of scientific evidence to back this up.^1,2,3 But is the effect the same for nonhuman animals? More specifically, can it help calm horses? While research is limited to certain species, some studies indicate that lavender may prove a beneficial tool in helping certain resident species stay calm in stressful situations.^4,5,6 While this isn’t the case for every species or for every individual, there is evidence that the scent and possibly the topical application of lavender could have a calming effect on horse residents.^7,8,9,10  In this resource, we will take a brief look at the current research available and whether the findings have application in sanctuary settings. First, let’s take a quick peek at the lavender components most responsible for the effects we see. 

Relaxing Properties

While lavender contains a number of other components that have been studied for their effects on human and nonhuman animals^11,12, linalool and linalyl acetate are most associated with the calming effects of lavender.^13,14  While there are a number of studies on the topical and oral administration of lavender in various species, we will focus mostly on research studying the inhalation of the essential oil but will cover a couple on the topical application of it as well.^15,16,17 We will not review research on oral administration, and we advise sanctuaries not to give essential oil to residents orally. The oral studies used different forms of lavender supplements.

The Research 

Reviewing Five Studies

There have been multiple studies investigating the effects of lavender on horses. Here is what some of them have found:

One study found that exposure to humidified air that contained 20% lavender essential oil significantly decreased heart rate in horses exposed to a loud sound that caused them acute stress.⁷  

Another study found that horses exposed to a diffuser with 20% lavender (to 80% water) during transport had lower cortisol levels. Cortisol is often used as a way to determine how stressed a nonhuman animal may be. High cortisol levels generally indicate that an individual is stressed. In this study, heart rate didn’t vary significantly between the control (the group that was only exposed to a diffuser that only contained water) and the treatment group (the group that was exposed to lavender-scented air). The authors concluded that this was a promising indicator that lavender could help lessen stress in horses while being trailered and transported.⁸

A third study applied diluted lavender oil directly to the skin of the horses, who were then presented with several different stressful scenarios such as exposure to a novel object (traffic cone) in their space, being stalled with and without visual contact with another horse, and the sudden introduction of a yellow cube in their space. The findings found significant differences in heart rate and cortisol levels between horses in the control and treatment groups. However, because the lavender was applied topically, we don’t know how much of the effect was from the smell of lavender or how much was due to the topical application that was absorbed into the skin.⁹

In yet another study, researchers found that while heart rate or cortisol levels didn’t differ significantly, heart rate variability did. The reason this is important is due to the parasympathetic component of heart rate variability, RMSSD. Horses exposed to diffused lavender had their RMSSD raise significantly. Without diving deep into physiology, this essentially suggests lavender caused these horses to relax. An important thing to note about this study is the fact that these horses were not exposed to any intense stressors. Of course, this is dependent on individuals, as someone might find being haltered and walked into an outdoor space stressful, but signs of this were not reported.  Another notable finding was that removing the scent removed the calming effect. Basically, lavender didn’t have a lasting effect once it was removed.¹⁰

A fifth study also used the topical application of diluted lavender oil (diluted with vegetable oil) to study possible calming effects in horses. In this study, the horses all performed stereotypic behavior. Stereotypies are repetitive, unvarying behaviors that have no apparent function. In this case, each horse studied performed stall circling, likely due to the management practice of stalling them for up to 22 hours a day. Each horse was their own control. No treatment was applied for the first 2 days, and their behavior was recorded over the same 3-hour period. On days 3-10, each horse had lavender oil (diluted to 4% in almond oil) rubbed slowly into their forehead. Researchers found that by day 10, 40% of the horses had stopped performing stall circling altogether during the 3-hour period, and another 40% of the horses were observed to have significantly reduced the time they spent stall circling. The remaining 20% were not significantly affected. However, we remain uncertain how much of the effect was directly related to the absorption of lavender through the skin or if the scent played a significant role in reducing this stereotypic behavior.¹¹

Lavender Oil May Cause Skin Irritation
While there was no evidence of irritation in the above studies, some studies in humans indicate lavender oil could be an allergen, though an uncommon one, and cause skin irritation.^12,18 It’s important to remain on the safe side and always dilute lavender oil and discuss its topical application with a veterinarian before attempting topical application. 

It is important to look at all the studies, not just the ones that support the effectiveness of lavender. For example, one study found no significant difference in heart rate or cortisol between the control and treated horses when exposed to loud sounds while stalled. The cortisol results were inconclusive due to the fact that baseline cortisol levels already varied significantly before the treatment, indicating an issue. So unfortunately, this limits what we can confidently glean from this study.¹⁹

Limitations Of These Studies

The number of horses in each of the studies was small (7-28 individuals), and the more data we have, the more confident we can be about the soundness of the findings. Some of these studies also had contradictory results, though this may be due to their different methods or the conditions under which they gathered data. Either way, more compassionate studies that do not involve exploitationExploitation is characterized by the abuse of a position of physical, psychological, emotional, social, or economic vulnerability to obtain agreement from someone (e.g., humans and nonhuman animals) or something (e.g, land and water) that is unable to reasonably refuse an offer or demand. It is also characterized by excessive self gain at the expense of something or someone else’s labor, well-being, and/or existence. are needed to determine the effectiveness of lavender in reducing stress in horses in different circumstances. For now, many of these studies demonstrate lavender oil scent and topical application as promising instruments in reducing stress in horse residents. 

Practical Applications For Sanctuaries

Always Consult Your Veterinarian First!
We cannot stress enough the importance of talking with your vet before attempting new treatments that could affect a resident’s health. We do not know the full effects lavender oil or supplements may have on horse (or other) residents. It could possibly cause allergic reactions or interfere with medications. Though uncommon, allergic reactions in humans have been noted as side effects of ingesting oils. In large enough amounts, ingested oils could become toxic. Skin irritation has also been seen in humans from the topical application, though this is rare. Of the studies we looked at, no horses suffered adverse effects, but that doesn’t mean it isn’t possible. It’s important to consider the possible risk factors. While a small amount is unlikely to harmThe infliction of mental, emotional, and/or physical pain, suffering, or loss. Harm can occur intentionally or unintentionally and directly or indirectly. Someone can intentionally cause direct harm (e.g., punitively cutting a sheep's skin while shearing them) or unintentionally cause direct harm (e.g., your hand slips while shearing a sheep, causing an accidental wound on their skin). Likewise, someone can intentionally cause indirect harm (e.g., selling socks made from a sanctuary resident's wool and encouraging folks who purchase them to buy more products made from the wool of farmed sheep) or unintentionally cause indirect harm (e.g., selling socks made from a sanctuary resident's wool, which inadvertently perpetuates the idea that it is ok to commodify sheep for their wool). a horse, there have been instances where cats accessed products with lavender oil in them and licked them, causing some pretty serious side effects.

Using lavender to calm horse residents during stressful situations is a promising aid. It is also fairly inexpensive (well, it is somewhat expensive, but a little goes a very long way!), easy to procure, dilute, and administer. There are a variety of situations where caregivers may find the use of lavender helpful in preventing or reducing stress in horse residents. Here are just a few:

• During trailering and transport
• During active rescues
• In quarantine spaces for new residents
• In living spaces for residents that must be temporarily separated
• Possibly in spaces with individuals that need to be less mobile for a time due to injury
• During hoof trims
• During health checks
• During introductions
• During teaching/learning sessions (standing still, accepting touch, learning to be comfortable with a fly mask being put on) with a resident 
• During vaccinations
• As sensory enrichment

A Note On Sourcing Lavender Oil
If you decide you’d like to utilize lavender essential oil with your horses, it is important to do a little research first to choose and purchase one responsibly.  There are a number of ethical considerations involved, including the rights of workers who help manufacture these products, the environmental impact of these products, and whether the company that sells these products also tests them on animals. Here is a list of some things to look for when purchasing lavender essential oil:

1. Uses sustainable harvesting methods
2. Ensures the lavender is fair trade
3. Doesn’t test on animals
4. Avoids the use of pesticides
5. Lists their distillation process and quality testing on their site

While it can be difficult to find a brand that participates in all of these practices, trying to at least identify a brand that has sustainable harvesting methods, is fair trade, organic if possible, and isn’t tested on animals goes a long way.

We generally do not provide links to specific brands as we do not endorse any brand, company, or organization. However, we’ve compiled a list of a few places with at least some of the above practices for your consideration:

Peace With The Wild
https://www.peacewiththewild.co.uk/product-brands/peace-with-the-wild/page/2/ 
https://www.peacewiththewild.co.uk/product/lavender-essential-oil-15ml/

Mountain Rose Herbs
https://mountainroseherbs.com/principles/sustainability/ 
https://mountainroseherbs.com/lavender-essential-oil

Rocky Mountain Oils
https://www.rockymountainoils.com/we-promise
https://www.rockymountainoils.com/organic-lavender/p

Sanctuary Scientists

Sound, reliable research requires a solid framework and controlled studies covering many details to collect valid data and provide accurate results. For example, controlled studies will try their best to ensure that every possible factor is kept the same for each individual or group, except the individual or group being studied, who will have a single different factor introduced to them. You can learn a little more about controlled studies here. However, it is possible for you to be a sanctuary scientist and to learn more about your residents and how best to meet their needs.

Compassionate Science Only 
We have mentioned it before, but this can’t be overstated: We at OSP fundamentally disavow animal experimentation and any “use” of animals for human purposes. No resident should ever be forced into a situation that might cause them harm for the sake of knowledge. Ensuring residents are not emotionally, mentally, or physically discomforted or harmed is paramount in compassionate science. Examples of compassionate science at sanctuaries may look like:

– Giving residents choices to learn their preferences. For example, do Frankie, Loretta, and Danu seem to prefer the scent of peppermint over the scent of cinnamon or sage? Do you observe any changes in behavior when they are exposed to their scent of choice? Does their heart rate or respiratory rate change?

– Making environmental changes and recording their behavior or using other non-invasive measurements. For example, does Allie exhibit more exploratory behavior and increased activity when we place scratching posts further out in their outdoor space over placement closer to their indoor living spaceThe indoor or outdoor area where an animal resident lives, eats, and rests.? Or does Sinda walk into the trailer more quickly when there is a light in there?

The best way to practice compassionate science in many situations is to let the residents choose. If they indicate they don’t like an essential oil diffuser, take it away or ensure they have the choice to walk away from it. Ideally, you are just offering them the option to participate in an activity or interact with something if they find it neutral or positive. Giving the choice to walk away is not always possible during things like dental exams or medical treatments. During those times, you can assess whether the addition of something like a lavender-scented diffuser has the potential to help and make observations and check heart rate (collect data) if it doesn’t cause additional stress to the resident.

Remember, the goal of sanctuary science is to better the life of the individual! Purposefully putting residents in potentially harmful situations, whether they be emotionally, mentally, or physically harmful, is unacceptable. Let’s make science what it should be – compassionate and non-exploitive!

What Does ‘Unacceptable’ Mean?
At The Open Sanctuary Project, unacceptable means that we cannot condone (or condone through omission) a certain practice, standard, or policy. See a more detailed explanation here.

While a lot goes into setting up a well-controlled experiment, you can start simply by introducing the scent of lavender to a resident with a diffuser, cloth with diluted oil held near their nose, or some other novel way and checking their heart rate before and after. We recommend repeating the “experiment” several times in the same context for more reliable results. Before you do all of this with the lavender, however, we also recommend that you go through the same motions without the lavender and record those results first. Remember to use the same diffuser (before it has had lavender in it) or type of cloth treated only with water and check their heart rate before and after exposure just like you will when you introduce the lavender to ensure it isn’t some other factor affecting their heart rate. Try this without a potential stressor first, then try it in a more somewhat stressful situation (an already necessary one, not for the sake of knowledge gained) such as during a hoof trim, health checkThe Open Sanctuary Project uses the term "health check" to describe health evaluations performed by caregivers who are not licensed veterinarians. While regular health checks are an important part of animal care, they are not meant to be a replacement for a physical exam performed by a licensed veterinarian., or trailering.

We mentioned repeating the same research under the same context as being important. It is important to control as much of the environment as possible to limit any interruptions or disturbances. That means, ideally, nothing should change in the environment between the first time you check their heart rate and the second or third time you check, other than the farrierSomeone who provides hoof trimming and care, especially for horses or cows continuing with their work. If repeating this research over a series of days, you must also replicate the environmental factors as much as possible. Otherwise, this can affect the results you get and not provide you with accurate data. This is because a new factor can affect the results you might get.

Here are some examples of things that should ideally be the same:

• Time of day
• Same farrier
• Same caregiverSomeone who provides daily care, specifically for animal residents at an animal sanctuary, shelter, or rescue.
• Same social situation
• Same weather
• Same sounds
• Same location/sights
• Same diffuser or cloth
• Same status of resident health
• Same type/brand of lavender oil

One Last Thing:
Remember the individual. What works for one resident doesn’t necessarily for another. They have personal preferences and dislikes. There may be a resident that finds the scent of lavender unpleasant. Always be on the lookout for any signs of avoidance or behavior that indicates stress or anxiety, and be ready to remove the offending scent or ensure they can walk away from it. 

We hope you find these bite-sized science resources helpful at your sanctuary. The aim of these resources is to provide sound scientific information that may have a practical application in sanctuaries. We hope you’ll stay tuned for more Science For Sanctuaries. In the meantime, let us know if you have any experience with aromatherapy for horse residents or other resident species. We love hearing from you and will do our best to answer any questions! Also, please contact us if you have any questions or concerns. It is important that we constantly improve our knowledge base with the most accurate, compassionate information possible.

Infographic

One last thing! You can read and share this information in our handy infographic. Check it out here!

SOURCES

1. Physiological Effects Of Inhaling Fragrances | International Journal Of Aromatherapy

2. The Effects Of Lavender Aromatherapy On Stress And Pain Perception In Children During Dental Treatment: A Randomized Clinical Trial | Complementary Therapies In Clinical Practice
3. Effects Of Orally Administered Lavender Essential Oil On Responses To Anxiety-Provoking Film Clips | Human Psychopharmacology: Clinical And Experimental
4. Influence Of Lavender Essential Oil Inhalation On Aggressive Behavior Of Weaned Pigs | Journal Of Applied Animal Science (Non-Compassionate Source)
5. Aromatherapy For Travel-Induced Excitement In Dogs | American Veterinary Medical Association
6. Effects Of Scent Enrichment On Behavioral And Physiological Indicators Of Stress In ZooAn organization where animals, either rescued, bought, borrowed, or bred, are kept, typically for the benefit of human visitor interest. Primates | American Journal Of Primatology (Non-Compassionate Source)

7. Effect Of Lavender Aromatherapy On Acute-Stressed Horses | Journal Of Equine Veterinary Science (Non-Compassionate Source)
8. The Use Of Lavender Aromatherapy To Relieve Stress In Trailered Horses | Journal Of Equine Veterinary Science (Non-Compassionate Source)
9. Lavender Essential Oil Decreases Stress Response Of Horses | Environmental Chemistry Letters (Non-Compassionate Source)
10. Effect Of Aromatherapy On Equine Heart Rate Variability | Journal Of Equine Veterinary Science (Non-Compassionate Source)
11. Topical Aromatherapy With Lavender Essential Oil In Horses With Circular Ride In Manger: Preliminary Study | Compendium Of Veterinary Sciences (Non-Compassionate Source)
12. Lavender And The Nervous System | Evidence-Based Complementary And Alternative Medicine  (Non-Compassionate Source)
13. Phytochemical And Biological Strategies To Improve Essential Oils Content In Lavender | PhD Dissertation, Keefah Al-Garallaa, Mississippi State University (Non-Compassionate Source)
14. The Effects Of Lavender Oil Inhalation On Emotional States, Autonomic Nervous System, And Brain Electrical Activity | Journal Of The Medical Association Of Thailand (Non-Compassionate Source)
15. Effects Of Inhaled Linalool In Anxiety, Social Interaction And Aggressive Behavior In Mice | Phytomedicine (Non-Compassionate Source)
16. Effectiveness Of Silexan Oral Lavender Essential Oil Compared To Inhaled Lavender Essential Oil Aromatherapy On Sleep In Adults: A Systematic Review Protocol | Jbi Evidence Synthesis (Non-Compassionate Source)
17. Effects of lavender on anxiety: A systematic review and meta-analysis | Phytomedicine (Non-Compassionate Source)
18. Cytotoxicity Of Lavender Oil And Its Major Components To Human Skin Cells | Cell Proliferation In Basic And Clinical Sciences  (Non-Compassionate Source)
19. The Use of Equine Lavender Aromatherapy to Suppress Stress | FASEB Journal (Non-Compassionate Source)

Non-Compassionate Source?
If a source includes the (Non-Compassionate Source) tag, it means that we do not endorse that particular source’s views about animals, even if some of their insights are valuable from a care perspective. See a more detailed explanation here