The most common allergies in horses
There are a number of types of allergies that are common in horses.
Insect allergy and sweet itch
The most common allergy in horses is hypersensitivity to insect bites, especially to the saliva of biting midges (Culicoides). With sweet itch, horses may rub the mane, tail and belly raw. The itch is severe, the skin becomes damaged, and the signs often worsen each year.
Certain breeds such as Icelandics, Welsh ponies, Shetlands, Connemaras and Friesians appear more sensitive.
To support the skin in horses with sweet itch and insect allergy, supplements can help, such as Hilton Herbs Bye Bye Itch and PUUR Culico.
Atopy and environmental allergies
Atopy is the second most common form of allergy in horses. They react to substances in their environment, such as pollens from grasses, trees and weeds, but also to house dust mites, storage mites, moulds and dander. Horses sensitive to indoor allergens often have more problems when stabled.
Warmbloods, Thoroughbreds, Arabians, Morgans and Quarter Horses seem to have increased susceptibility.
With environmental allergies, respiratory support can be useful and skin support with PUUR Apis.
Sensitivity to other insects
Besides midges, horseflies, botflies and other stinging insects can cause strong skin reactions. Some horses develop large, firm, itchy swellings, especially under the belly or on sensitive areas.
In horses that react strongly to environmental stimuli and insect bites, HorseFlex AllerRelief can help support resilience to these triggers.
Pollen allergy and respiratory signs
Some horses mainly develop respiratory signs in spring or summer: coughing, watery or mucous nasal discharge and getting out of breath more quickly during work. These “hay fever-like” signs are often caused by pollen. Symptoms are usually worst on warm, dry, windy days.
Respiratory support with a supplement such as Audevard Balsamic Control and anti-inflammatory support with omega-3 fatty acids, for example Dr. Baddaky Omega-3, may help.
Read more about pollen allergy in the blog Pollen allergy in horses.
Sun allergy
With sun allergy, the skin reacts oversensitively to sunlight. Skin can die off and slough, which is painful and looks dramatic. An underlying liver problem or exposure to phototoxic plants such as ragwort may be involved. Sun allergy should always be assessed by your vet.
Reducing allergens: what can you do yourself?
You can’t remove exposure completely, but you can often reduce the burden considerably. That can be the difference between recurring problems and a largely stable situation. Management is a key pillar, especially with atopic dermatitis and hypersensitivity to insect bites.
Reducing house dust mites
House dust mites are found in bedding, hay, feeders and on stable surfaces. For sensitive horses, keep the environment as dust-low as possible. Rubber mats as flooring, cleaning with a damp method instead of dry sweeping, and thorough cleaning of buckets and feeders help to reduce allergens.
Store feed in airtight containers in a cool, dry place, buy smaller amounts so it stays fresh, keep stable humidity low (below 45%) and temperature moderate. This creates a less favourable environment for mites.
Reducing insect contact
For horses with sweet itch or insect allergy, limiting bites is essential. Start with pasture choice: avoid areas with standing water, muck heaps, compost or lots of livestock. Bringing horses in around dusk and dawn also helps, as midges are most active then.
Fine mesh sweet-itch or fly rugs and masks offer a physical barrier. Treating rugs or stable textiles with a permethrin-based repellent can add protection. Stable fans disrupt insect flight paths and improve airflow.
More tips on protecting your horse against horseflies and flies: How to protect your horse against horseflies.
Limiting pollens
For pollen-sensitive horses, timing and planning matter. Turn out when pollen counts are lower: early morning, later evening or right after rainfall. On warm, windy days with high pollen, consider limiting turnout.
In the stable, closing doors and windows during peak hours can help, as long as ventilation remains adequate. Wash pads, rugs and boots used outside regularly so pollen doesn’t build up.
Reducing moulds
Mould spores are common in dusty or mouldy hay, wet bedding and poorly ventilated stables. Ventilate well, keep stalls dry and remove mouldy material immediately. Feed hay outside or switch to steamed hay or haylage if dust and mould are an issue.
Avoid forest rides during wet autumn weather if your horse is sensitive, and dry clothing and tack outside rather than in a damp tack room.
Treatment: what really works?
Allergies are almost always chronic and require long-term management. In many cases, signs are initially treated with antihistamines or corticosteroids to suppress itch and inflammation. Skin care products and anti-inflammatory supplements such as HorseFlex Boswellia can help reduce overall burden.
However, these mainly address symptoms, not the cause. For confirmed allergic disease there is one treatment that modulates the immune system itself: immunotherapy.
Immunotherapy: addressing the cause
Allergen-specific immunotherapy (desensitisation) is evidence-based and helps the immune system tolerate allergens again. After allergy testing, for example with the PAX Horse Allergy Xplorer, you find out which allergens your horse is sensitive to. A tailored formulation is then created.
Allergens are administered in gradually increasing doses, usually by injections or orally. The aim is a less vigorous immune response and fewer clinical signs. Many horses improve within months, though full effect often takes 6–12 months. In many horses, corticosteroids and other symptomatic meds can later be reduced or stopped.
Immunotherapy is suitable long term, competition-legal and generally very safe. Most horses remain on a maintenance dose once controlled.
Food allergy in horses
In addition to environmental and insect allergies, some horses develop food allergy. It is less common but can greatly affect skin, gut and performance. The immune system reacts abnormally to certain proteins in the ration, leading to itch, hives, gut issues such as diarrhoea or mild colic, and unexplained weight loss.
Common allergens include cereals (oats, maize, barley, wheat), soya, alfalfa and certain plant proteins. Because signs resemble other allergies, it’s important first to exclude other causes such as parasites, infections or insect allergy.
Diagnosing food allergy
Diagnosis is usually based on an elimination diet for 4–8 weeks. Remove likely triggers and switch to a novel protein for your horse, for example coconut, pea or lupin protein, combined with a different forage type such as teff or timothy instead of alfalfa. Then reintroduce ingredients one by one to see what triggers a reaction.
Blood tests measuring IgE antibodies can provide supporting information and guide elimination, but are rarely sufficient alone to confirm food allergy.
What to feed with food allergy?
Once trigger ingredients are identified, avoid them long term while ensuring a complete, balanced ration. Hypoallergenic feeds with one clear protein source and grain- and soya-free feeds can be helpful. Fibre-rich components such as soaked beet pulp, hay pellets and specific hay types support gut health and reduce allergen load.
Omega-3 fatty acids can temper inflammatory responses in skin and gut and improve comfort. An example is Dr. Baddaky Omega-3, a high-quality marine omega-3 supplement.
Equine allergies are often chronic and require a combination of measures: reducing allergen contact, targeted symptom control, possible dietary adjustments and, where confirmed, immunotherapy to retrain the immune system.
If your horse has recurring itch, skin issues or respiratory problems, consult your vet to investigate whether allergy is the cause. With the right diagnosis, sound management and targeted support, you can usually improve your horse’s comfort and quality of life significantly.
Questions about horse allergies? Contact us at veterinarian@vetsend.co.uk.
