An animal shelter is a facility that houses and disposes of homeless, lost, or abandoned animals; primarily a large variety of dogs and cats. In the past, such a shelter was more commonly referred to as a dog pound, a term which had its origins in the impoundments of agricultural communities, where stray cattle would be penned up or impounded until claimed by their owners.
The goal of the modern animal shelter is to contribute to the public health by keeping animals that otherwise will be free on the streets, usually in unsanitary conditions. They aim to provide a safe, loving and caring environment until the animal is either reclaimed by its owner, placed in a new home, placed with another organization for adoption or euthanized. Many shelters temperament test animals before they are put up for adoption to determine if the animal is adoptable and, if so, what the appropriate home environment would be. However, in the United States, many government run animal shelters operate in conditions that are far from the ideal. In the wake of the Financial crisis of 2007–2008 many government shelters have run out of adequate space and financial resources. Currently, in U. S., 64% of all incoming animals left at a government run shelter are euthanized. Owners who choose to drop a pet off at one of these shelters are only giving that pet a 36% chance of survival. Shelters unable to raise additional funds to provide for the increased number of incoming animals have no choice but to euthanize them, sometimes within days. The statistics are less grim at no-kill shelters.
Usually public animal shelters around the world euthanize animals that are not adopted within a set period of time (usually 7 to 14 days); others, however, limit that policy to only putting down animals that are in distress due to age or illness. Most private shelters are typically run as no-kill shelters. In Europe of 30 countries included in a survey only three (Germany, Greece and Italy) did not permit the killing of healthy stray dogs.
United States 
In the United States there is no government run organization that provides oversight or regulation of the various shelters on a national basis. However, many individual states do regulate shelters within their jurisdiction. One of the earliest comprehensive measures was the Georgia Animal Protection Act of 1986. The law was enacted in response to the inhumane treatment of companion animals by a pet store chain in Atlanta. The Act provided for the licensing and regulation of pet shops, stables, kennels, and animal shelters, and established, for the first time, minimum standards of care. The Georgia Department of Agriculture was tasked with licensing animal shelters and enforcing the new law, through the Department's newly created Animal Protection Division. An additional provision, added in 1990, was the Humane Euthanasia Act, which was the first state law to mandate intravenous injection of sodium pentothal in place of gas chambers and other less humane methods. The law was further expanded and strengthened with the Animal Protection Act of 2000.
Currently it is estimated that there are approximately 5,000 independently run animal shelters operating nationwide. Shelters have redefined their role since the 1990s. No longer serving as an until-death repository for strays and drop-offs, modern shelters have taken the lead in controlling the pet population, promoting pet adoption, and studying shelter animals health and behavior. Shelters, and shelter-like volunteer organizations, responded to cat overpopulation with trap-neuter-release programs that reduce feral cat populations and reduce the burden on shelters.
“Approximately 5 million to 7 million companion animals enter animal shelters nationwide every year, and approximately 3 million to 4 million are euthanized (60 percent of dogs and 70 percent of cats). Shelter intakes are about evenly divided between those animals relinquished by owners and those picked up by animal control. These are national estimates; the percentage of euthanasia may vary from state to state.” 
In Canada, the government-run Humane Society shelters specialize in dogs, cats, and small rodents.
Some shelters will also keep reptiles and/or parrots.
United Kingdom 
In the United Kingdom, animal shelters are more commonly known as rescue or rehoming centers, and are run by charitable organizations. The most common rescue and rehoming organizations are the RSPCA, Cats Protection, and the Dogs Trust.
Most larger cities in Germany either have a city shelter for animals or contract with one of the very common non-profit animal organizations throughout the country, which run their own shelters. Most shelters are populated by dogs, cats and a variety of small animals like mice, rats and rabbits. Additionally there are so-called Gnadenhöfe for larger animals. They take cattle or horses from private owners who want to put them down for financial reasons. Under German law the euthanization of animals is restricted to medical reasons or cases where the animal is dangerous, not controllable and actually poses a danger to humans (Gefahr im Verzug - exigent circumstance). Most dangerous animals, such as aggressive dogs (possession of some special breeds is restricted), are locked away until rehoused to a controlled environment.
See also 
- Abandoned pets
- Black dog bias
- Cat colony
- Dog camp
- No-kill shelter
- Overpopulation in companion animals
- Pet adoption
- Goshala, cow shelters in India
- Diamond, Wendy (13 May 2007). "America’s Foreclosed Pets". The Huffington Post (Cleveland). p. 1. Retrieved 6 August 2009.
- Lewis, Laura Dawn (2009). Laid Off, Now What?!? Financial Savvy, Book 1. Couples Company, Inc. p. 29. ISBN 978-0-9671042-6-3.
- World Society for the Protection of Animals & The Royal Society for the Prevention of Cruelty to Animals International (2007). Report Stray Animal Control practices (Europe) An investigation of stray dog and cat population control practices across Europe. p. 18.
- "Animal Protection - Ga Dept of Agriculture". Agr.georgia.gov. Retrieved 2012-10-16.
- "Georgia Humane Euthansia Act, O.C.G.A. Â§4-11-5.1". Animal Law Coalition. Retrieved 2012-10-16.
- "Judge Issues Permanent Injunction Against Illegal Use of Gas Chambers in Georgia". Animal Law Coalition. Retrieved 2012-10-16.
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- "Pet Statistics". ASPCA. Retrieved 2 April 2013.