Horse allergy (IgE horse)

Horses spread allergens through their dander, hair, sweat and saliva. These allergens stick to clothing, riding gear and saddles and so also end up in the home or the car. This test measures the amount of IgE antibodies against horse dander in the blood, in kU/l. Some horse allergens are similar to those of other mammals, such as cat and dog; antibodies against those animals can therefore also give a positive result in this test.

• Sensitization to horses: the body has made IgE antibodies against horse allergen
• A starting point with symptoms that occur around horses, in a stable or riding school, or on contact with clothing and gear of someone who handles horses

The GP mainly looks at the history: when and where the symptoms occur. With a positive result and matching symptoms, the main advice is to limit contact with horses and with clothing and gear from the stable. If needed, medication for the nose, eyes or airways follows, and with symptoms that are not brought under control with this, a referral to an ENT specialist, lung specialist or allergist may follow.

A positive IgE result shows sensitization, not allergy: it only says that there are antibodies, not that you get symptoms from them. The Dutch medical specialists' guideline (FMS) on upper airway allergy says this literally and recommends choosing a test for single allergens based on the history of the symptoms; for food allergy, the FMS guideline on food challenge testing calls the history of the symptoms the cornerstone of diagnosis and a food challenge in hospital the gold standard. The result therefore only means something if it fits when, where and after contact with what you get symptoms. A positive result without symptoms is not treated.

• Sensitization without symptoms is common; the result can only be interpreted together with the history of the symptoms.
• Related allergens can recognize each other's antibodies (cross-reaction), for example pollen and nuts or fruit; a positive result then does not mean that this particular allergen causes the symptoms.
• The test measures all proteins from the allergen source together; testing for individual proteins (components) can say more in case of doubt.
• Laboratories use different measurement methods and cut-off values; results from different labs cannot be compared one to one.

Horse allergy is less common than cat or dog allergy, mainly because fewer people are in daily contact with horses. In people who handle horses a lot, such as riders and people who work in a stable, the chance of sensitization is higher. Sensitization is more common than the allergy itself.

Useful with symptoms that occur around horses or in a stable or riding school: sneezing, a blocked or runny nose, itchy or watery eyes, coughing, shortness of breath or itchy bumps on the skin. Also with symptoms near someone who has just been with horses. In people without such symptoms, the test adds nothing: sensitization without symptoms is not a disease and is not treated.

• NVKC, allesovertesten.nl: Allergie (RAST)
• FMS Richtlijnendatabase: Allergie van de bovenste luchtwegen, module Aanvullende diagnostiek
• FMS Richtlijnendatabase: Voedselprovocatie, module Plaatsbepaling diagnostiek voedselallergie
• Thuisarts.nl: Ik heb allergie
• Thuisarts.nl: Ik heb lange tijd of vaak neusklachten door een allergie