Explanation

Animal dander mix (allergy): what is measured?

The test measures, in one go, IgE antibodies against a fixed mix of dander from 4 animals: cat, dog, horse and cattle. According to the Longfonds (Dutch lung foundation), with an animal allergy you react to the skin flakes (dander) and not to the hair. Dander floats in the air, sticks to furniture and clothing and, according to Thuisarts.nl, stays in the home for months after an animal has gone. IgE is the type of antibody that, in an allergic reaction, triggers mast cells to release histamine; the body only makes these antibodies after it has previously been in contact with an allergen, and this is called sensitization. Because the 4 animals are tested together, the result gives one number and a verdict of positive or negative, but not which animal the antibodies are directed against. Rodents, rabbit and birds are not in the mix.

What can it detect?

Sensitization to at least one of the 4 animals in the mix: the body has made IgE antibodies against dander from one or more of them
An indication of whether symptoms around animals, at home or when working with animals may have an allergic cause

Result

What does the result mean?

Positive result

A positive result means that you have IgE antibodies against dander from at least one of the animals in the mix: sensitization. That is not the same as an allergy, and the test does not say which animal the antibodies are directed against. In people who get symptoms near a cat, dog, horse or cow, such as sneezing, a blocked or runny nose, itchy or watery eyes, a skin rash or shortness of breath, a positive result fits an animal allergy. According to the Longfonds, symptoms often start within a few minutes, but sometimes only hours later, and even people without an animal of their own can get symptoms in a home where an animal lives or has lived. In people without such symptoms, a positive result only means that the antibodies are there; no treatment follows.

Negative result

A negative result means that no IgE antibodies against cat, dog, horse or cattle dander were found. An IgE-mediated allergy to these animals is then much less likely. An allergy to animals that are not in the mix, such as rodents, rabbit or birds, is missed. Symptoms at home or around animals can also have other causes: an allergy to house dust mite or molds, or non-allergic inflammation of the nose from irritants such as smoke and odors.

After an abnormal result

The GP mainly looks at the history: with which animal, when and where the symptoms occur, and if needed a test for single animals follows to determine which animal it is. With an allergy, the main advice is to stay away from that animal as much as possible; according to Thuisarts.nl, symptoms can then last for months because dander stays in the home. With symptoms from work, the occupational physician can help, and with symptoms that are not controlled with medication or with asthma, referral to an ENT specialist, lung specialist or allergist may follow.

Reliability

How reliable is the test?

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 recommends choosing an IgE test for single allergens based on the history of the symptoms; a mix tests more allergens at the same time, so a low sensitization without clinical meaning can more easily make the result positive. Sensitization to animals also occurs in people who never have symptoms from them, partly through cross-reaction between related proteins of different mammals. The mix is therefore mainly a first step: a negative result makes an allergy to these 4 animals less likely, a positive result can be looked into further with a test for single animals.

What can affect the result?

Sensitization without symptoms is common; the result can only be interpreted together with the history of the symptoms.
The test does not say which animal you react to; that requires a test for single animals.
Antibodies against one animal can, through cross-reaction, also give a positive result for another animal that causes you no symptoms.
Laboratories use different mixes, measurement methods and cut-off values; results from different labs cannot be compared one to one.

Who it is for

Who is the test useful for?

Useful for

Useful with symptoms that occur near cats, dogs, horses or cows, or in homes or stables where these animals are: sneezing, a blocked or runny nose, itchy or watery eyes, coughing, shortness of breath or a skin rash, also when these symptoms occur when working with animals, for example on a farm or at a riding school. If it is clear which animal is involved, a test for that single animal says more. In people without such symptoms, the test adds nothing: sensitization without symptoms is not a disease and is not treated.

How common is it?

Allergy to pet dander, such as from cats and dogs, is, alongside pollen and house dust mite, a known cause of allergic nose and eye symptoms, and can make asthma worse. Allergy to horse or cattle mainly plays a role in people who spend a lot of time with these animals, such as in equestrian sport or on a farm. Sensitization is more common than the allergy itself.

Thuisarts.nl, Longfonds and the FMS guideline on upper airway allergy; no Dutch prevalence figure has been checked

Drawbacks and risks

A positive result without symptoms can lead to unnecessarily giving away a pet, while sensitization without symptoms does not need treatment.
A negative result can give false reassurance if the symptoms are caused by an animal that is not in the mix.

Get tested