Essential oils and aromatherapy have (again) gained prominence in veterinary medicine, but research on safety and efficacy has lagged behind the popularity of this age-old practice. While essential oils are reported to have many important health benefits, using these products without knowing where they came from, how they work, and whether they are safe can be dangerous for your horse.
Essential Oil Basics
Essential oils are made up of chemicals extracted from plant leaves, stems, wood, bark, and / or fruits. Together, these compounds are classified as secondary plant metabolites that plants produce to survive in the environment. In contrast to primary metabolites, secondary metabolites do not take part in basic life functions such as cell division and growth, respiration, storage and reproduction. Instead, secondary metabolites protect the plant in some way (e.g. against insects, pathogenic organisms and the ultraviolet rays of the sun).
The list of essential oils available is extensive. The essential oils most commonly used in modern medicine include basil, bergamot, chamomile, devil’s claw, eucalyptus, frankincense, geranium, ginger, lavender, lemongrass, peppermint, tea tree, valerian, white willow, and yucca.
Benefits of Essential Oils: What Science Shows
In vitro (laboratory) study results show that some essential oils have pronounced antimicrobial activity against both bacteria and fungi (Ebani and Mancianti 2020). This includes multi-resistant bacterial strains such as Pseudomonas spp. and Staphylococcus spp. In addition to bactericidal properties, essential oils are said to have antibiofilm properties as well. Biofilms are collections of bacteria and the protective “slime” they produce, which forms an impenetrable barrier around pathogenic organisms.
Essential oils also show promise as insecticides. A study showed that tea tree oil extracted from Melaleuca alternifolia has excellent adulticidal in vitro effects against stable flies (Dillmann et al. 2020). These blood-sucking flies are a nuisance for horses, interrupt feeding and can trigger an escape reaction with their painful bites (even in the middle of a competition). Biting flies can also transmit disease, including equine infectious anemia.
Another group (Cox et al. 2020) reported that a commercial herbal topical spray applied once a day for 28 days appeared to be effective in treating hypersensitivity to insect bites. The spray contained extracts of lemongrass, peppermint, camphor, corn and patchouli. These essential oils were selected for their previously proven immunomodulatory (changes the immune response), antihistamine, antipruritic (anti-itch), anti-inflammatory, antiallergic, analgesic (pain reliever) and larvicidal (kills juvenile insect) activities.
A published study also supports the widely recognized role of lavender as a sedative when used as aromatherapy, as found in decreased heart rate variability in eight dressage horses (Baldwin and Chea 2018).
Essential oils, especially carvacrol, are being researched as antiparasitics (Trailovic et al. 2021). This would be a welcome solution to the widespread resistance of roundworms (Parascaris sp.) To all three major anthelmintic (deworming) families.
In general, aromatherapy uses natural essential oils to improve the psychological and physical wellbeing of animals – a broad and comprehensive description. As such, these products, which cannot and cannot be classified as medicinal products, are also used to treat painful musculoskeletal disorders, immune stimulation, antioxidant activity, soothing solutions and gastric ulcers. Essential oils can also be administered by inhalation using a commercially available nebulizer to improve respiratory health.
Take these other benefits into account
With essential oils in conjunction with, not instead of, modern medicine and with veterinary expertise, we can:
- Reduce the need for systemic antibiotics. Using products that can fight infections without antimicrobials promotes good antibiotic management and reduces the pressure to create or treat antibiotic-resistant strains.
- Minimize the need for anti-inflammatory drugs and their side effects. Nonsteroidal anti-inflammatory drugs (such as phenylbutazone or “bute”) can contribute to stomach ulcers or colitis, and corticosteroids can cause laminitis.
- Maintain gut microbiome health. Any drug has the potential to disrupt the delicate balance of microbes in the appendix and colon. Dysbiosis can lead to diarrhea, behavior changes, a weakened immune system, and other negative consequences.
- Reduce pollution from drugs, drug by-products, or chemicals.
safety
Just like other complementary and alternative therapies, horse owners tend to view essential oils as generally safe. In reality, the safety of essential oils remains largely unclear and both their positive and negative properties require further study.
In mice and rats, essential oils are associated with liver, kidney and reproductive toxicity as well as changes in blood vessels and can cause oxidative stress (Ebani and Mancianti 2020). In addition, a series of articles recently published in the Journal of the European Food Safety Authority warned consumers not to view essential oils as irritants to the skin, eyes and respiratory tract. Human study results report photosensitization after exposure to sunlight and dermatitis after topical application of essential oils. Lavender, peppermint, and tea tree oil seem to be the biggest culprits.
As with joint supplements and other complementary and alternative therapies, choose a quality product. Inferior oils may not contain the listed ingredient in the specified concentration or amount. Products can be contaminated with other ingredients that can affect your horse’s health.
Finally, you should be clear about which essential oils the equestrian federations prohibit. The FEI, USEF, and some jockey clubs have added various herbs and oils to their Prohibited Substances List.
Take home message
To use essential oils in a safe and meaningful way, work with a trained aromatherapy veterinarian. You can find one on the Veterinary Medical Aromatherapy Association membership directory (www.vmaa.vet).
