A teacher says her pet pooch saved her life by detecting the early stages of her lung cancer.

Colleen Ferguson feared something was wrong when beloved German shepherd Inca began to take an unusual interest in her breathing.

Concerned the dog’s keen sense of smell was picking up on something amiss, the 60-year-old booked herself in for a private health test.

Weeks later she received the devastating news scans had revealed a golf-ball-sized tumour on her left lung.

Mrs Ferguson, who was teaching at Five Acre Wood School in Boughton Lane, Maidstone at the time of her diagnosis, said she might not be here if it wasn’t for her pet.

She said: “She would just stop completely still and focus on my breath and sit there sniffing, waiting for the out breath.

“I knew she wasn’t begging for food or anything and dogs could detect health problems, so I booked a health MOT.”

Video: Amazing Inca sniffed out his owner's cancer

A non-smoker, Mrs Ferguson, from Headcorn, had no symptoms of ill health other than tiredness.

After a biopsy confirmed the tumour was cancerous, the special needs teacher was admitted to Guy’s Hospital in London where she had the lump and half her lung removed earlier this month.

Now, less than two months after her diagnosis, she is recovering at home, and waiting for confirmation she is cancer free.

Diseases are known to have characteristic odours which dogs can detect.