A humane society is a group that aims to stop cruelty to animals. In many countries, the term is used mostly for societies for the prevention of cruelty to animals (SPCA). In the United Kingdom, and historically in the United States, such societies provide waterway rescue, prevention and recovery services, or may give awards for saving human life (e.g., Glasgow Humane Society and Massachusetts Humane Society).
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.
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.