Euthanasia for a bed sore?

My mother died of lung cancer in 2000. Before they upped her morphine dosage so that she became comatose, she had horrible pain from a bed sore on her tailbone. She had cancer in all her bones at that point and it was eating her ribs. The worst pain though, was from the bed sore. Now would it be allowable to euthanize people if they weren't dying but probably would not be mobile again and thus likely to suffer from chronic bed sores?