Pet dander is generally worse in older animals than in younger animals, as older animals slough off more skin cells than younger animals. Dander is microscopic, and can be transported through the air. Through the air, dander can
enter the mucous membranes in the lungs, causing allergies to some individuals. Skin flakes that come off the main body of an animal are dander while the flakes of skin called dandruff come from the scalp.