Size of the Pet
Many families come to the shelter in search of a small dog because they live in an apartment. However, there are many small dogs, such as Jack Russell terriers that require a great deal of exercise and outdoor time. These are not ideal apartment pets at all. Some larger breeds, such as greyhounds, are actually perfectly suited to sleeping on a sofa all day.
Also, toy breeds are sometimes nippy and less patient with children. Their size also makes them more sensitive to rough touch, so toy breeds may be unintentionally injured by an unsupervised child.

Picking a pet by personality and temperament is often the best, rather than by size, color or breed. Some of the best adoptions occur when you can describe the personality, activity level and other temperament qualities to an adoption counselor, who can then suggest potential matches for you.
Pure Breed or Mixed Breed?
The Labrador Retriever gained its reputation as an all-around family companion, great with children, friendly to people and other dogs, an easy-keeper for an active family. But a Labrador Retriever in a family that is not prepared for a large, boisterous, energetic dog that retrieves everything that’s not nailed down and can clear a coffee table with a swing of the tail is a dog that quickly becomes a liability. Labs with no manners end up in animal shelters and in rescue, their owners disillusioned with the breed.
A pure bred dog or cat from a reputable breeder or breed rescue group can make wonderful pets. However, mixed breed dogs and cats make great pets too, and mixed breeds have some advantages over pure breed dogs.