Equine allergies have increased significantly over recent decades, and today many horses suffer from various hypersensitivity symptoms. Of course, improved diagnostics compared to the past also contributes to increased detection. Allergies can present as respiratory symptoms, skin problems, itching, digestive issues, or discharge from the eyes and nostrils. The most common equine allergies are linked to dust, molds, pollen, insects (such as biting midges), or certain feeds.
Why have allergies increased?
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Environmental conditions
Horses spend more time indoors, where air quality may be poor. Dusty bedding, moldy hay, and inadequate ventilation expose horses to airway irritation and allergies.
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Over-hygiene and low exposure
Research suggests that an overly “clean” environment for young horses may cause the immune system to develop in an imbalanced way, increasing the risk of allergies—an effect known as the “hygiene hypothesis.”
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Climate change and pollen seasons
Warmer and longer summers have increased pollen levels and extended pollination seasons, exposing sensitive horses to more allergic triggers.
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Breeding
Certain breeds or bloodlines may be more prone to allergies. Some Thoroughbreds and ponies, for example, appear to be more sensitive to certain environmental factors.
Prevention
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A clean, well-ventilated stable
Avoid dusty bedding. Use, for example, pellets or dust-free peat. Ensure good ventilation, especially in winter.
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High-quality, dust-free hay
If needed, soak hay with water before feeding or use steamed / pre-dried hay to reduce dust particles.
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Turnout and exercise
Daily turnout and movement support respiratory and immune system health.
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Insect protection
Sweet itch (allergy to biting midge bites) can be prevented with insect rugs, non-toxic repellents, and keeping the horse indoors in the early morning and evening when midges are most active.
Treatment
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The elimination principle
The foundation of allergy management is avoiding the trigger. This may mean changing bedding, hay, or other feeds, or improving stable air quality.
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Medication
If needed, a veterinarian may prescribe antihistamines, corticosteroids, or other anti-inflammatory medications to control symptoms.
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Immunotherapy (allergy vaccination)
An allergy test can be performed to identify allergens. This allows avoidance of the trigger or initiation of desensitization therapy, where the immune system is trained to tolerate a specific allergen.
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Topical management of skin symptoms
In sweet itch, for example, corticosteroid creams, cooling gels, and skin oils can be used to reduce itching.
Summary
The rise in equine allergies is linked to many modern environmental and management practices. Good stable hygiene, dust-free forage, sufficient turnout, and taking the horse’s individual needs into account are key to prevention. If symptoms occur, it is important to consult a veterinarian and determine the most appropriate treatment approach.
Sources:
- Couëtil, L. L. et al. (2007). “Equine Asthma Syndrome”
Journal of Veterinary Internal Medicine
https://doi.org/10.1892/0891-6640(2007)21[356:EAS]2.0.CO;2
- Robinson, N. E. (2001). “Current Therapy in Equine Medicine”
- Marti, E. et al. (2008). “Equine allergic diseases”, Veterinary Immunology and Immunopathology
https://doi.org/10.1016/j.vetimm.2008.02.016
- Karikoski, N. et al. (Finland): Equine respiratory problems and dust exposure
www.sele.fi (members only)
- AllHorse GP & AAEP (American Association of Equine Practitioners)
https://aaep.org
- Hygiene hypothesis
Also generalized in animal research: see e.g. Björnson et al. 2018 on allergies and environmental exposure in young animals.
