Two close friends in Halifax say you might want to pay attention the next time your dog starts acting strangely around you.

One is battling cancer; the other is a survivor.

In both cases, they say a family dog alerted them to the disease long before doctors found it -- and experts say they're probably onto something.

When Anamarija Wagner visits her friend Mechelle Pikel, Wagner’s dog, Benny is often the centre of attention – and that suits the eight-year-old Labradoodle just fine.

Wagner and Pikel have been friends for years and the two women have found themselves getting even closer in recent-months, thanks to some highly unusual behaviour from Benny.

“Well, every time I approached him, he always went towards my breasts and he wouldn't leave me alone,” said Pikel. “He kept barking, and then I realized there must be something wrong.”

There was: it was breast cancer.

After surgery in the summer, Mechelle's undergoing treatment. The wife and mother of four is forever grateful for an early diagnosis.

“I believe God used the dog to help me find the cancer,” Pikel said.

As remarkable as it is, that's not the end of the story.

Rewind to 2005 when Wagner's previous dog, Rocky, did the same thing by alerting her to Stage 2 invasive ductile carcinoma.

Rocky died six years later, leaving his owner heartbroken.

“I was so sad, and I thought to myself, ‘now, what am I going to do? I won't know if I ever get cancer again because I don't have my little cancer sniffer.”

The notion that dogs can actually “sniff out” cancer has been a compelling idea for decades.

Born with a sense of smell far superior to our own, it's believed canines can detect the volatile organic compounds produced by tumours.

In a paper published 14 years ago in The British Medical Journal, researchers tested whether dogs could detect bladder cancer in human urine.

The results were encouraging enough the journal noted “dogs have the potential to make a contribution in the field of oncology.”

None of this is overly surprising to those who work with dogs on a daily basis.

Long-time veterinarian Eric Carnegy says we're only beginning to understand, and harness, the power in a dog's snout.

“For example, we have 30 million little sensors in there, on our nose,” Carnegy said. “A dog has like 600 million, and the centre in their brain where they analyze all these senses, is like 40 times bigger than ours. So, when it comes to smell, dogs are the king.”

Said Wagner: "Rocky gave me my dognosis way before I had my diagnosis,” she said. “And, if it wasn't for him, I wouldn't be here.”

So the treatments continue for Pikel, with the love and support of family and friends, and no small amount of gratitude to a special canine – and a guarantee of extra attention for the rest of his life, which is just fine by Benny.

With files from CTV Atlantic’s Bruce Frisko.