Show them that you are responsible enough to take care of one. You can persuade your parents to get you a dog by convincing them that you are ready to take responsibility for the pet dog. Most parents don't want to invest their free time in looking after a pet dog.  If you can assure them that you can look after the dog without any help, they might be persuaded to get you a pet dog. Showing that you are pretty serious about getting a dog can also convince your parents.