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Updated June 09, 2015.

Definition:

Albumin is a major blood protein that is made by the liver. It is often a measure of nutritional status and of healthy liver function.

In animals, albumin can be secreted in the urine, saliva and skin. It is a common allergen, triggering allergy symptoms in susceptible people. Albumin is especially an important allergen in cats, dogs, horses, and most furry animals.

Since albumin is always the same size and shape, it is cross-reactive among many of these animals.

That is, if a person is allergic to cat albumin, for example, she will also likely be allergic to the albumin of other animals.