Merseyside Police said the dog was destroyed following the incident in Richard Kelly Close, Clubmoor last night.
Two women, aged 27 and 28 years, from Clubmoor, have been arrested on suspicion of an offence under the 1991 Dangerous Dogs Act.
A post-mortem examination on the man is due to take place later, the BBC reported.
Merseyside Police said the dog was out of control when officers arrived at the house and found the man's body in the garden of his home.
The women have been arrested under the section of the Dangerous Dogs Act which relates to an owner or a person in charge of the dog allowing it to enter a private property where it is not permitted to be and the animal injures a person.
"House-to-house inquiries are underway and Crime Scene Investigators are carrying out forensic examinations at the scene," the Sun reported.