The 3-3-3 rule is a guideline for transitioning a rescue dog into its new home and helping it to settle in. It suggests that the first three days should be used for adjusting to its new surroundings, the next three weeks for training and bonding, and the first three months for continued socialization and training.

Shelters are typically operated and funded by local governments, and shelter animals are kept in a facility and housed with other animals. Rescue groups, on the other hand, are generally operated by volunteers and funded by donations.

Puppies can also suffer from fear, anxiety and other lasting behavioral problems. Sometimes these issues don't show up until people bring the puppy home, only to be confronted with unpredictable, expensive and oftentimes chronic medical issues.