Cats are beloved family members of millions of Americans. Unfortunately, these pets are also allergen factories for as many as 25 percent of the population, according to the American College of Allergy, Asthma and Immunology.

Allergies to dogs are caused by dog dander. All dogs shed dander continuously. Dander is the microscopic bits of hair and skin that have a protein-based oil secretion on them.

Kids love pets, so parents may not realize that their infants have dog allergies until they have already adopted and bonded with a puppy. When suspicions allergy symptoms appear, it may be too late to break up the budding relationship.

Cats shed skin flakes and deposit them in their fur when they groom. This is dander. Allergy-causing proteins in the dander can provoke reactions including hives, rhinitis and asthma. Thorough removal of dander in the home will significantly reduce symptoms associated with a cat allergy.

According to the American Academy of Allergy, Asthma and Immunology, almost 15 percent of people in the United States experience some type of allergic reaction to pets such as cats or dogs. The primary cause of such allergies is pet dander—the dead skin cells cats and dogs shed on a daily basis.