Animal euthanasia is the act of killing an animal humanely, most commonly with injectable drugs. Reasons for euthanasia include incurable conditions or diseases, lack of resources to continue supporting the animal, or laboratory test procedures. Euthanasia methods are designed to cause minimal pain and distress. Euthanasia is distinct from animal slaughter and pest control.

Animal slaughter is the killing of animals, usually referring to killing domestic livestock. It is estimated that each year, 80 billion land animals are slaughtered for food. Most animals are slaughtered for food; however, they may also be slaughtered for other reasons such as for harvesting of pelts, being diseased and unsuitable for consumption, or being surplus for maintaining a breeding stock. Slaughter typically involves some initial cutting, opening the major body cavities to remove the entrails and offal but usually leaving the carcass in one piece. Such dressing can be done by hunters in the field or in a slaughterhouse. Later, the carcass is usually butchered into smaller cuts.