He was immediately taken to the hospital, where he received stitches. Police said he is not in a life-threatening condition.

At the time of the attack, the dog, which is 95 centimeters long and weighs 45 kilograms, was on a leash but was not muzzled.

Under the animal protection law, only five breeds of fierce dogs and their mongrels are required to wear muzzles. The five breeds are the Tosa dog, American Pit Bull Terrier, American Staffordshire Terrier, Staffordshire Bull Terrier and Rottweiler.

The Old English Sheepdog is not among them.

"My dog is really well-behaved. He has never attacked people,"

the dog's owner was quoted as saying to investigators. She believes the dog appears to have attacked the man after being surprised to see the food trash bin that he was holding, as another resident had once threatened him with a food trash bin, police said.

The police have booked the dog's owner on suspicion of negligence resulting in injury. (Yonhap)