A seven-month-old German shepherd has been hailed a hero after it was stabbed protecting a Darwin home from a group of youths attempting to break in as the owners slept.

Security guard Mobin Pour Nowrouz and his pregnant partner Yuni were asleep in their home in the suburb of Malak when the incident happened about 9:30pm on Wednesday.

Mr Pour Nowrouz, 26, was awoken by his partner's parents some time after the attempted break-in and found their dog Buddy in a pool of blood.

The dog had been stabbed in one of its back legs.

"He's a hero," Mr Pour Nowrouz said.

"Me and my partner were inside, she's four-months' pregnant.

"If Buddy wasn't there they might have just broken into the house, woken us up and stabbed us."

A witness told Mr Pour Nowrouz he saw five young people running away from the property.

The dog was expected to make a full recovery, but Mr Pour Nowrouz said vets explained to him that Buddy could have died if he was found much later.

"He means so much [to me]," he said.

"Every fortnight when I get paid I have to first buy his food and then do my own shopping."

A Go Fund Me campaign set-up by a stranger to help pay for Buddy's surgery bill exceeded its $5,000 goal only hours after going online.

"I'm going to get the receipt from the vet and the rest I'm going to donate to one of the animal shelters," Mr Pour Nowrouz said.

Police are calling for other witnesses to contact them.