Puppy saves owner's life in incredible way after he collapsed at home alone

It's not new information that dogs are fiercely loyal, but Luna the Jack Russell took loyalty to new heights after saving her owner's life.

Suffering a medical emergency while on your own could lead to devastating consequences if you're unable to get help fast enough - something which this pooch seemed to know.

Vaughn Marshall, 48, had just returned to his home in Melbourne, Australia, after taking Luna for a walk when he all of a sudden fell unwell.

Vaughn then collapsed and found himself unable to breathe or move in the extremely scary ordeal.

Luckily Luna was on hand to help and upon seeing her owner in distress, she ran outside in the hopes of getting someone's attention.

Fortunately she did and one of the last things Vaughn remembers was seeing a good Samaritan carry Luna back into the house before rushing to his aid and calling an ambulance.

When he arrived at the hospital, Vaughn was taken into intensive care where doctors said he'd suffered a pulmonary embolism. This happens when a blood clot blocks a blood vessel in your lungs - something which can prove deadly.

Luna's owner Vaughn had suffered a pulmonary embolism. (9News)

Symptoms of a pulmonary embolism include shortness of breath, chest pain and fainting, Mayo Clinic reports.

Other symptoms may include lightheadedness, fever, excessive sweating and a rapid or irregular heartbeat.

With the seriousness of his medical emergency in mind, Vaughn fears he might not have survived had Luna not been on hand to help.

"Who knows what the outcome might have been if Luna hadn't been there," he told 9News.

He went on to spend three nights in the ICU and is now back home with his heroic dog.

"If she wasn't already my best friend, she is now," Vaughn said of Luna. "I'm not sure if she has any idea of what she's done, she certainly knows she's been very spoilt ever since."

Luna has been hailed a hero for her life-saving actions. (9News)

Luna isn't the only pooch to have saved their owner's life; last year a border collie named Axel saved a 17-year-old from a severe brain injury.

Teenager Gabriel, from Spring in Texas, fell unwell while in his bedroom last year, something which Axel alerted his parents to.

It was later revealed that Gabriel had suffered a stroke and had he not received the medical attention he needed in the time that he did, Gabriel could have been left with 'permanent deficits that would have made him really nonfunctional and unable to live life'.

Gabriel spent a few days in hospital at the time and went on to make a positive recovery from the scary ordeal. His mom later credited Axel for saving her son.