Allergens from animals are some of the most common allergens that cause allergic reactions. The reason for the reaction is that allergen is secreted from the animal's skin cells, saliva, urine and the sebaceous glands, which cause the body's immune system to react.
Cat dander is small skin flakes from the cat's fur that contain the allergen Fel d 1, which can cause allergic reactions in sensitive people, but in itself is not dangerous.
Cow dander is a protein from cow's skin that can cause allergic reactions in people who are sensitive to it, and to find out if you are allergic, an allergy test can be performed that measures the levels of IgE antibodies to cow dander in your blood.
Dog dander is small flakes of skin that dogs can shed from their fur and can cause allergic reactions in people who are sensitive to the proteins found in the dander, such as Can f 1 and Can f 2.
Allergens from goose feathers are proteins that can cause allergic reactions, and if you suspect that you are allergic to goose feathers, you can carry out an allergy test to find out if you are sensitive to these proteins.