Pet adoption usually refers to the process of taking ownership of and responsibility for a pet that a previous owner has abandoned or otherwise abdicated responsibility for. Common sources for adoptable pets are

• Animal shelters, in the case of dogs also known as dog pounds
• Rescue groups
• Pets which are found out of captivity without identification, and which remain unclaimed by any owner
• Advertisements placed by individuals who are trying to find a new home for their pet
• Pets that have been abused or neglected and have been confiscated from the offending owner
• A fast growing source for pet adoption is online pet adoption through not-for-profit websites such as www.1-800-Save-A-Pet.com. Public service sites such as these have searchable databases of pets, maintained by thousands of animals shelters, and are searchable by the public.

Dogs adopted from shelters are often referred to as shelter dogs or pound puppies; dogs adopted from rescue organizations are often called rescue dogs (not to be confused with search and rescue dogs).

Pets become available for adoption for a variety of reasons. Some of the more common:

• Breeding: Breeders are a leading cause of overpopulation because they usually produce more pets than they can sell and often produce pets that do not fit their desired breeding specifications, and must be gotten rid of.
• Death: Owner dies and no one in the family wants to (or can) keep the pet
• Changed circumstances: Financial or living arrangements change drastically and people feel that they can no longer provide an appropriate home for the pet. This might also include someone having to move to a new living situation where the landlord or roomates do not allow a pet.
• Second thoughts: A pet was purchased after the spur of the moment decision or as a gift (frequently for Christmas). Some time afterward, owners discover that caring for the pet is much more work than expected, or requires more space or exercise than they are prepared to give
• Lost pet: Pet leaves home or cannot find its way back, and owner doesn't succeed in finding it.
• Health: Severe health problems make it impossible to have a dog in the house or impossible for the owner to care for the dog
• Moving across borders: People leave the country; quarantine laws in some countries can be traumatic to dogs and owners, so the dogs are often left behind

People deal with their unwanted pets in many ways. Some people have the pet euthanized (also known as putting it down or putting it to sleep), although many veterinarians do not consider this to be an ethical use of their resources for young and healthy animals. Other people simply release the pet into the wild or otherwise abandon it, with the expectation that it will be able to take care of itself or that it will be found and adopted. More often, these pets succumb to hunger, weather, traffic, or common and treatable health problems. More responsibly, owners will take the pet to a shelter, or call a rescue organization, where it will be cared for properly until a home can be found. Homes cannot always be found, however, and euthanasia is often used for the excess animals to make room for newer pets.

The central issue in the adoption of a pet is whether a new owner can provide a safe, secure, permanent home for the pet. Many shelters, pounds, and rescue organizations refuse to supply animals to people whom they judge cannot supply the animal with a suitable home.

A new owner might also face training challenges with a pet who has been neglected or abused.

Pets