If being around a cat or dog can cause you to sneeze, have itchy or runny eyes, or develop a skin rash, you may be one of the estimated 10% of the population that is allergic to animals. In dogs and cats, the most common cause of allergies in people is the dander in their skin and coat.
Contrary to popular belief, the hair of dogs and cats generally does not cause allergies. Instead, it is the dander of the pet causing reactions. Dander is the scales of dead skin that are constantly being shed by all mammals. Dander is similar to dandruff in humans, but much smaller and not usually able to be seen by the naked eye.