Allergy to animals is very common and can aggravate other allergies.

Pets are a major source of allergens, with cats being more likely to provoke an allergic reaction than any other domestic animal. The allergens are not in the animals' fur (contrary to popular belief), it is their coats that are very good "transporters" of allergens.

The allergen that comes from animals is often referred to as "dander". Animal danders are the most common nonseasonal, inhaled allergen. Animal danders may induce hayfever and asthma symptoms, or they may produce skin reactions such as urticaria.