'Lucky to be alive': Quick thinking pup saves owner's life outside Melbourne home

A Jack Russell terrier has been hailed a hero for alerting neighbours after her owner collapsed outside their home in Melbourne's south-east.

Vaughn Marshall called Luna a "lifesaver" and believes he might not have survived without her quick thinking.

The 48-year-old had just returned to his Frankston home from a walk with Luna when he collapsed, struggling to breathe and unable to move.

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Sensing her owner's distress, Luna ran from house to house, apparently searching for help.

The next thing Marshall recalled was a woman arriving with Luna in her arms and quickly calling an ambulance.

"I am just incredibly lucky," he said.

"She was barking across the road and the last thing I remember is her running around the corner."

Frankston Hospital intensive care consultant Dr Craig Johnston expressed concern that Marshall was on the verge of a heart attack.

"Who knows what the outcome might have been if Luna hadn't been there," he said.

Marshall was treated for a life-threatening blood clot, known as a pulmonary embolism.

After spending three nights in ICU, he is now recovering, with Luna by his side.

"If she wasn't already my best friend, she is now," he said.

"I'm not sure if she has any idea of what she's done, she certainly knows she's been very spoilt ever since."

Marshall has not only thanked Luna but also the woman and her partner who came to his aid.

He hopes to find and thank them.