This is a veterinary decision as much as a psychological one. The veterinarian must first rule out all medical causes (pain, seizures, brain lesions). Once organic disease is excluded, the question becomes one of welfare. An animal living in a constant state of hyper-vigilance, terror, and reactive aggression is not experiencing a good quality of life, even if its bloodwork is perfect. Behavioral euthanasia recognizes that mental suffering is as valid a reason for ending life as terminal cancer.

Understanding animal behavior is crucial in veterinary science. Animals often exhibit behavioral changes when they are stressed, anxious, or in pain. By recognizing these behavioral cues, veterinarians can diagnose and treat underlying medical issues more effectively. For instance, changes in appetite, water intake, or elimination habits can be indicative of various health problems. Moreover, behavioral observations can also help veterinarians identify potential welfare concerns, such as social isolation, inadequate housing, or lack of mental stimulation.

For deep dives into the science and clinical application, the following works are highly regarded: