Meaning: This sentence tells us that a group of people related to each other decided to take a young dog into their family as their own and keep it as a companion.
Choice of Words: The word "family" refers to a group of people related to each other, usually living together. "Adopted" means to take someone into your family as your own child. "Puppy" is a young dog. "Pet" is an animal kept for pleasure and companionship.