Nelson, a six-year-old black and tan German Shepherd, sprang into action to help save the Sunderland man's life.

Police received a call from security firm G4S when one of their guards at Norgas House, in Killingworth, North Tyneside, had failed to make a regular check-in call in the early hours of the morning.

Officers, including dog handler Pc Sarah Gray and her Northumbria Police dog Nelson, went to the building and made several attempts to contact the guard.

They tried ringing his mobile phone and knocking on several windows and doors but failed to rouse him.

The officers then smashed their way through two doors and started their search of the building for the guard, who was from Sunderland.

Nelson proved dogs really are man's best friend when he was called into action to help with the search.

He soon found the 48-year-old man, who had suffered a severe diabetic episode and was conscious but confused and needed urgent medical help.

An ambulance was called and paramedics were able to give the man a strong dose of medication to stabilise his condition and prevent him from falling into a potentially lethal diabetic coma.

Pc Gray today praised Nelson's actions and said that without him the search, on September 8, could have taken a lot longer.

She said: "Nelson made a tremendous difference to our rescue. He was able to significantly narrow down the areas to search and managed to locate the man within 20 minutes.

"Without his help this search could very easily have taken hours, which could have had very serious consequences for this security guard."