Thanks to the development of civilization, humans have been able to tame the natural world and create comfortable living conditions for themselves.
Today we live in comfortable, warm homes, with access to running water and electricity, domesticated animals, faster transport with cars and public transportation, food and other products are readily available in stores, if we have any health problems we’re guaranteed medical aid, etc. If these things didn’t exist, most us would have a hard time surviving even a few days.
Human-domesticated animals are in a slightly different situation. Even if they are thrown out, they are capable of handling themselves in a new situation thanks to their instincts, which they will never lose. Dogs are capable of surviving in many different conditions, some of them quite extreme. Many of them do not require human care at all and survive just fine without it. But the chances of survival for a weakened or injured dog falls almost to zero, especially if up until that point the dog was living peacefully alongside a human, only to be suddenly deprived of this care and shelter.
This was the unfortunate loss that met a certain pitbull, who was heartlessly treated by his previous owner.