The humanization of care for domestic animals is a common theme within the reality of pet caregivers, as well as within the daily lives of veterinary medicine professionals. Within this perspective, euthanasia can shorten the suffering of animals in a terminal state or with uncontrollable pain, which cannot be minimized through analgesics, sedatives or any other type of treatment, and also alleviate the suffering of their caregivers, even make it such a difficult decision to make. This conduct must be seen as the last resort to be done, when no treatment has a positive effect, and the veterinarian must be concerned with humane techniques, and thus induce death quickly, painlessly and peacefully for the patient. The present study has as general objective to search in the literature the circumstances of when the euthanasia of small animals is recommended. The methodology is based on the literature review, whose publications will be directed to the scientific area, being made bibliographic searches through sources constituted by electronic resources in the electronic base Scientific Electronic Library On-line (SciELO) and Google Scholar, with published documents between 2010 and 2022. It is concluded that despite being a difficult choice, both for pet caregivers and for professionals involved in veterinary clinics, it is a necessary procedure for animals undergoing irreversible treatments or that are in great suffering, being considered a humanitarian measure.