Posties trying to deliver our mail were attacked by dogs almost 2,500 times last year.
And in some cases, the victims were left with permanent disabilities following their ordeals.
The shocking figures were revealed as Royal Mail launched its Dog Awareness Week.
Dr Shaun Davis, director of safety at Royal Mail, said: “The coronavirus pandemic has placed an increasing reliance on our people.
“Safety is of paramount importance and never more so than now.”
Dave Joyce, of the Communication Workers Union, said: “Put the dog in a secure room before opening the door to collect deliveries.”
There were 1,622 days of absence in the past year due to attacks on Royal Mail staff.
The number was slightly down on 2018 but in many areas attacks increased – Guildford in Surrey went up from 26 to 47 and Chelmsford in Essex rose from 15 to 33.
Mark Wilding, who delivers in Llandrindod Wells, Powys, was one of the attack victims.
He said: “The dog jumped up and bit me on my hand. It then started biting my hi-viz jacket and trousers.
“Eventually the owner managed to drag the dog off me.
“My hand wouldn’t stop bleeding, so I had to go to hospital.”
Last November, an SAS soldier gave his special forces attack dog the kiss of life after it was hurt in a bomb blast.
The three-year-old Belgian Malinois, called Victor, is believed to have suffered a seizure after being hit by the shock wave from the improvised explosive device.
It happened as an SAS team was clearing a suspected Islamic State compound in Iraq.
The SAS soldier could see that although the dog’s heart was still beating it was no longer breathing.
He carried it to safety and began giving mouth-to-mouth resuscitation in a desperate attempt to save its life.
After around 40 seconds, the animal began to cough and almost immediately got back on its feet.