Jason Lee suffered a terrible injury to his arm as he protected his face when the dog struck in Meltham.
The wound is so severe it has been described as potentially life-changing.
The 41-year-old is now in a specialist unit at Bradford Royal Infirmary where he has undergone plastic surgery.
The dog struck when Mr Lee approached the house in Copley Avenue at 12.15pm on Tuesday.
The dog ripped a large chunk of flesh from his forearm.
A spokesman for the Communication Workers’ Union said: “It has bitten a large lump of flesh and muscle from his forearm, causing a large hole.
“He is not very well and is under sedation at Bradford Royal Infirmary where he is being visited by his family. This is possibly a life-changing injury.”
The union official said there was still a concern about the number of postal deliverers attacked by dogs.
He added: “We are launching a big campaign next week which will encourage customers to be more responsible.
“We get a huge increase in dog attacks during the summer when doors are open and dogs are running free.”
A West Yorkshire Police spokesman said: “A man was left with serious arm injuries as a result of the incident.
“Inquiries are currently continuing to establish the full circumstances.”
The dog has not been seized by police but officers are due to speak to its owner today.
(Huddersfield Examiner - July 12, 2013)
