A robber kicked a 92-year-old woman in the head and left her bleeding and badly injured on her doorstep.
Edith Brickhill had opened her back door to let her dog out and was bending down when she was kicked and punched in the face.
The man stole cash from her purse before fleeing, leaving Mrs Brickhill battered and bleeding on the ground.
The attack happened at around 7.20pm on Wednesday at the pensioner's home in Moston, north Manchester.
Mrs Brickhill suffered severe bruising, two large lumps to her forehead and a cut nose.
It is believed the robber escaped with just £30.
Police said Mrs Brickhill had been left extremely shaken up and distressed.
Detective Inspector Denise Sweeney said: "At this early stage, we are still investigating what motivated such a senseless attack on a defenceless, vulnerable pensioner as she was letting her dog out.
"Whatever the motive, it was an act of sheer cruelty and we are doing everything we can to get to the bottom of it."
Police are appealing for witnesses and have stepped up patrols in the area.
Janet Boswell, Mrs Brickhill's daughter, told the BBC: "She said she is frightened to go back to the family home where she has lived for 45 years.
"She said she is afraid this person will come back and kill her."
A man was arrested on suspicion of assault and has been bailed until February 11, pending further investigations.
Anyone with information is asked to call Greater Manchester Police on 0161 872 5050 or Crimestoppers, anonymously, on 0800 555 111.