But instead of attacking and scaring him off, her lovable pet just wagged his tail and licked the offender.
Taking matters into her own hands, ballsy Jean Walsh, from County Durham, slammed the criminal up against a wall and shouted at him, "Get out of my house!"
Her courage shocked the burglar, who told her there were other men upstairs in the building, and she immediately called the police.
Within seconds, they arrived and caught him red-handed, trying to make off with her television.
The grandmother-of-11 told her local paper: "I was just acting on adrenaline really.
"Later that night when I got into bed, I laughed to myself and was quite shocked with what I had done.
"But in that moment I just did what I had to do. I wanted him out of my house."
Although the retired secretary had been let down by her border collie Marley, she remained unperturbed.
Tallen Kirby, 24, pleaded guilty to burglary and separate offences of theft of a parked car and criminal damage to a police cell. He was jailed for 15 months at Teesside Crown Court.
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