Animal shelter in the context of Sheriff of Cork City

Neutering, from the Latin neuter ('of neither sex'), is the removal of a non-human animal's reproductive organ, either all of it or a considerably large part. The male-specific term is castration, while spaying is usually reserved for female animals. Colloquially, both terms are often referred to as fixing. In male horses, castrating is referred to as gelding. An animal that has not been neutered is sometimes referred to as entire or intact. Often the term neuter[ing] is used to specifically mean castration, e.g. in phrases like "spay and neuter".

Neutering is the most common method for animal sterilization. Humane societies, animal shelters, and rescue groups urge pet owners to have their pets neutered to prevent the births of unwanted litters, which contribute to the overpopulation of unwanted animals in the rescue system. Many countries require that all adopted cats and dogs be sterilized before going to their new homes.

The domestic rabbit (Oryctolagus cuniculus domesticus) is the domesticated form of the European rabbit. There are hundreds of rabbit breeds originating from all over the world. Rabbits were first domesticated and used for food and fur by the Romans. Rabbits may be housed inside, but the idea of the domestic rabbit as a house companion, a so-called house rabbit (similar to a house cat), was only strongly promoted starting with publications in the 1980s. Rabbits can be trained to use a litter box and taught to come when called, but require exercise and can damage a house or injure themselves if it has not been suitably prepared, based on their innate need to chew. Accidental interactions between pet rabbits and wild rabbits, while seemingly harmless, are strongly discouraged due to the species' different temperaments as well as wild rabbits potentially carrying diseases.

Unwanted pet rabbits sometimes end up in animal shelters, especially after the Easter season. In 2017, they were the United States' third most abandoned pet. Some of them go on to be adopted and become family pets in various forms. Because their wild counterparts have become invasive in Australia, pet rabbits are banned in the state of Queensland. Domestic rabbits — bred for generations under human supervision to be docile — lack survival instincts, and perish in the wild if they are abandoned or escape from captivity.

An animal sanctuary is a facility where animals are brought to live and to be protected for the rest of their lives. In addition, sanctuaries are an experimental staging ground for transformative human–animal relations. There are five types of animal sanctuaries determined by the species of the residents: companion animal sanctuaries, wildlife sanctuaries, exotic animal sanctuaries, farmed animal sanctuaries, and cetacean sanctuaries.

Unlike animal shelters, sanctuaries typically do not seek to find new human homes for animals, and instead maintain each animal until their natural death (either from disease or from other animals in the sanctuary). In some cases, an establishment may have characteristics of both a sanctuary and a shelter; for instance, some animals may be in residence temporarily until a good home is found and others may be permanent residents. The mission of sanctuaries is generally to be safe havens, where the animals receive the best care that the sanctuaries can provide. Animals are not bought, sold, or traded, nor are they used for testing or experimentation. Additionally, no parts of nor secretions from the animals, such as eggs, wool, or milk, are commodified. The resident animals are given the opportunity to behave as naturally as possible in a protective environment.

In some countries, there is an overpopulation of pets such as cats, dogs, and exotic animals. In the United States, six to eight million animals are brought to shelters each year, of which an estimated three to four million are subsequently euthanized, including 2.7 million considered healthy and adoptable. Euthanasia numbers have declined since the 1970s, when U.S. shelters euthanized an estimated 12 to 20 million animals. Most humane societies, animal shelters, and rescue groups urge animal caregivers to have their animals spayed or neutered to prevent the births of unwanted and accidental litters that could contribute to this dynamic.