Pets often carry fleas and ticks, and these can transfer to children. They cause severe itching, allergies, and can transmit some dangerous diseases. Good pet hygiene is important to avoid these problems.

Cats release an allergen, Fel D 1, into the environment which can provoke and worsen asthma. Similarly, dogs, too, release an antigen. These are two of the commonest antigens involved in childhood allergic diseases. 66% of children sensitized to cat antigen have been found to have either asthma, eczema, or rhinitis.

These antigens can persist in the home environment for months after the animal is removed. If there is a family history of allergic disorders, the animal should be removed from the home several months before the baby is born. About a third of childhood asthma can be attributed to allergen sensitization, and this may not become obvious for some months after a pet is acquired.