Many educators enjoy introducing animals into their classrooms for show and tell, as class pets or teaching tools. While animals bring fun and engaging opportunities for students, many schools are shying away from this once common practice due to accidents, zoonotic diseases and allergens. It is estimated that approximately 10 percent of the population may be allergic to animals and a higher rate of 20 to 30 percent of individuals with asthma have pet allergy symptoms. Even if a pet is not in the vicinity, a student can have an allergic reaction due to allergens that can be easily transported on clothing and other paraphernalia. The cause of pet allergies is usually not fur as this is a popular belief, but the culprit is actually pet dander or flakes of dead skin. Animal dander can remain in an environment for at least six months even after the offending pet has been removed. The longer the animal remains, the higher the amount of dander in the air, which should be of major consideration when planning for long term incorporation of classroom pets. Many people are also allergic to animal saliva and urine as well. Common animals that cause allergic reactions are dogs, cats, birds, hamsters, rabbits, mice, gerbils, rats and guinea pigs; but any warm blooded mammal that sheds dander can produce allergens. There have also been studies that show some people have allergies to cold-blooded amphibians and reptiles as well. Although many times roaches and other insects are considered to be pests instead of pets, some educators enjoy using insects as teaching tools. Some insects, such as cock roaches and midges have been shown to trigger asthma and allergies, and current research suggest they may actually cause asthma to develop in preschool aged children. Pet allergy symptoms are usually respiratory and may include coughing and wheezing, red, itchy eyes, sneezing and runny or stuffy nose. Skin reactions can also occur and are usually in the form of a breakout where the person has come into contact with saliva or urine. It is rare, but hives can also occur.