Allergies are the body's disproportional reaction to harmless substances. They're usually hereditary, so if you or your partner is allergic to something, there's a chance your child will be, too. However, you won't necessarily be allergic to the same substances. Allergies typically develop by the time you're 10 years old.
Cat allergies are commonly triggered by the proteins secreted in a cat's sebaceous glands and in their saliva and urine; they're also commonly set off by skin flakes, or dander, that the cat sheds. When your body comes in contact with one of these allergens, your immune system will try to neutralize the bothersome substance. It produces immunoglobulin E, which then instructs your mast cells and basophils to release some 40 chemicals to fight off the allergen. One of these chemicals is histamine.
Histamine is responsible for the inflammation of your nose and airways; noticeable symptoms caused by cat allergies include a runny nose, watery eyes, sneezing, coughing and wheezing. Some highly sensitive people can even develop a rash when they come in contact with a cat. These symptoms affect both adults and children alike. One clue that your child may be allergic to cats is if you have a cat or and your child's cold-like symptoms last more than two weeks or are year-round. A visit to the doctor can help determine whether your child's allergic symptoms are being caused by a pet feline, or whether the source is another type of allergen. You may be referred to an allergist who can perform more extensive skin testing in order to determine your child's sensitivities. While skin tests can be done on infants, they're considered most reliable on children older than two.