Mercy dogs were trained during World War 1 to comfort mortally wounded soldiers
Mercy dogs, also called casualty dogs, were first trained by the Germanic armies of the 19th Century, but their popularity only grew. The sanitatshunde were trained to find the wounded and dying anywhere on the battlefield. Sometimes they carried medical supplies to help the wounded care for themselves until they could find care from a doctor or medic. If the soldier was too far gone for medical care, the dog would stay with him as he died, to ensure he wasn’t alone.
If a mercy dog on the battlefield found a wounded man, it would return to friendly lines with its own leash in its mouth, indicating that one of their own was out there and in need of help. Most importantly, the dogs were able to distinguish between a dead and unconscious man. If he was dead, the dog would move on. If he were dying, the dog would stay with him.