Plymouth, Devon -
Kimberley May, her fiance Martin, and their three-year-old daughter Olivia were all sound asleep when the thief broke into their house.
But as the raider rifled through cupboards the noise woke up Toby the family's British Giant bunny in his kitchen cage.
The 4.5kg, two-feet long pet began stomping so loudly on the floor that the intruder was caught on the hop and left.
Kimberley said: "We went to bed on Wednesday at about 10pm. In the early hours of the morning Toby our rabbit did five loud thumps.
"I sort of half woke up then realized he'd stopped and went back to sleep.
"When I went downstairs every single cupboard and drawer were open, there were bits out everywhere, then we started noticing things were missing and we phoned the police."
Kimberley, a nurse, is convinced that two year-old Toby's thumping scared the thief off from their house in Plymouth, Devon.
She found a hoard of items left piled up on the sofa which she thinks the burglar was preparing to take but left behind.
She added: "Because of Christmas and my birthday just gone, I had loads of gift sets and perfumes that they'd laid out across the sofa.
"We think that when the rabbit thumped it scared the burglar off and they left all the stuff they were going to take.
"He's like a little dog, if you whistle him he comes.
The crook still managed to get away with other valuables including a treasured First World War medal that belonged to Kimberley's great-grandad.
Kimberley added: "They managed to take a laptop, an iPad and my handbag with my purse and everything in, but the worse thing was my great granddad's medal.
Detective Constable Nick Bloom said: "We believe the family was burgled between 10.30pm on Wednesday February 6 and 7am on Thursday February 7.
Toby still has some way to go before he is fully grown - British Giant rabbits can reach up to 5.9 kg.
Owner Kimberley, 30, said monster bunny Toby was so big he lives in a cage built for a Labrador.
Kimberley and online salesman partner Martin, 33, got their prized pet from an animal adoption center who took him in as an unwanted pet.
She said: "He's playful, really friendly, and he doesn't mind my three-year-old crawling all over him. He's like a small dog really.
"He has the run of the house and at night he goes in a dog's crate. It's a Labrador-sized cage.
"When he thumps on the floor its incredibly loud - you can hear it echoing around the house."
On the night of the burglary Toby stomped his five-inch long feet so loudly on the plastic floor of his crate that he managed to wake Kimberley up.
She said: "The rabbit had obviously seen the burglar when he went into the kitchen.
"I heard him thump five times on the bottom of his cage and I woke up, sat up, then turned over and went back to sleep.
"As I've done that the bed springs have made a loud creaking sound, so the guy has probably heard movement and made a run for it."
Although the thief managed to take some valuables Kimberley fears the break-in could have been even worse had it not been for Toby.
She added: "If he hadn't been scared off he could have come upstairs looking for things. My daughter was asleep up there - it could have been really dangerous.
"Toby has done the job of a guard dog. We're so proud of him we've rewarded him with a new tunnel to play with.
"It's a cat's tunnel obviously because he needs a big one."