With training, pets can help their owners to lead a more normal life, as with the case of guide dogs for the blind. Animals such as "hearing dogs" are trained to help deaf people identify and react to specific signals such as the doorbell, fire alarm and telephone.

Assistance animals also fulfill many other invaluable roles, including working as sheep and cattle dogs, as sniffer dogs used for detection of drugs, tracker dogs, mountain, sea and avalanche rescue animals, and police dogs. It is interesting to talk to the handlers of working animals and to learn that they are still regarded as pets, which have simply been trained for specific purposes.

The coexistence and cohabitation of humans and pets has become an area of investigation in which a growing number of psychologists, scientists, veterinary surgeons and doctors around the world have become interested.

For example, scientists believe that the presence of a pet can lead to a reduction in stress, a decrease in blood pressure and the lowering of anxiety levels. Scientific studies have also shown that the chances of recovery among heart patients who have pets are higher than those who are not pet owners.

Tests have revealed that stroking dogs and cats can lower the blood pressure and heart rate of the human. This may be related to the simple fact that caring for certain pets introduces added responsibilities, such as having to go out to exercise a dog, shopping and generally leading a more active life. Pet owners have often confessed that it is the dog, which makes them exercise. Walking the dog also leads to many conversations and social interactions that might otherwise not have taken place.