Based on a six-year study of 9,000 children, German researchers have stated that having dogs may reduce a child's risk of developing allergies. In theory, exposure to pet-related allergens builds ups a child's immunity and helps reduce risk of allergies, asthma, eczema, and hay fever.

The study used parents' answers on detailed surveys from birth to age six. Blood samples were also taken from a number of participants to test for antibodies in the blood stream.

The same protective effect was not noted in children with repeated exposure to dogs, but without dogs in their home.