A resident walks her dog over a snow-covered sidewalk following an overnight snow storm in Toronto, Ontario.
A resident walks her dog over a snow-covered sidewalk following an overnight snow storm in Toronto, Ontario March 2, 2014. An extreme cold weather alert is in effect in the Toronto area as a U.S. National Weather Service forecast calls for an area of snow extending from the Central Plains into the Northeast. REUTERS/Hyungwon Kang

Two women dog owners have been jailed for 12 months after their dog, a Presa Canario cross-breed that has been left unfed for 45 hours, ate alive a 79-year-old pensioner in Britain.

Witnesses told the Liverpool Crown Court they heard Clifford Clarke, a 79-year-old retired hospital porter, yelling "get off me" as Charlie, a bull mastiff-type dog owned by Della Woods and Hayley Sulley, mauled him to death.

Neighbours ran to the scene and tried in vain to help Clarke. One was even armed with a golf club and tried to beat the animal off. Clarke suffered horrific injuries in the 15-minute attack.

Police who were called to the scene eventually shot the beast dead.

Sulley and Woods were both charged under the Dangerous Dogs Act to offences of allowing a dog to enter a place where it was not allowed to be and where it injured a person. They pleaded guilty to both offences.

It was learnt that the dog, which the owners left unattended as they went to a barbecue, eventually had escaped their garden. They left the beast without water and shade on a warm day, the court heard.

The dog was then able to enter the garden of his next-door neighbour Clarke who was then cooking meat from his kitchen. Investigation reports said Charlie ingested large amounts of tissues, prompting the court judge to say that Clarke had "literally been eaten alive."

At the time of the attack, the court heard Charlie was so crazed that even after being shot at once by a policemen, it managed to still get up and tried to attack and bite the end of the policeman's rifle.

It was "the worst thing I have ever seen," the NZ Herald quoted an unidentified officer as he described the scene.

Forensic tests later revealed the beast, along with two other dogs the couple owned, had not been fed or watered for 45 hours before it killed Clarke. The dogs were so hungry they tried to eat their plastic food bowl and ate cigarette butts, bird food and dirty water, the court also heard.

Judge Mark Brown told the owners they were lucky not to be charged with manslaughter, yet noted Clarke's death was "entirely avoidable."

"Mr Clarke suffered a horrific death and you have taken away from his family the love and companionship he would have provided," the NZ Herald quoted Brown.

"Mr Clarke was literally eaten alive by Charlie when large parts of tissue were ingested by the dog. That was a very shocking, appalling and tragic event."

The owners face two years at prison the most.