Animal euthanasia

Animal euthanasia (euthanasia from ; "good death") is the act of putting an animal to death or allowing it to die by without it facing extreme medical measures. Reasons for euthanasia include incurable (and especially painful) 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 although in some cases the procedure is the same.
In pet animals, this process is commonly referred to by euphemisms such as "put down" or "put to sleep".