A woman is now cancer-free thanks to her pet dog. Maureen Burns owns a pet dog that acted strange when his owner started worrying. Burns said her pet collie named Max may be ill. She thought her pet was showing signs of aging since he was already 9 years old. But as it turned out, Burns was the one who was sick and not the dog.

According to animal experts, many dogs know when a person is about to eat in the house. Even before pet owners can go to the kitchen, dogs will go running and wait for scraps that might reach the floor.

Burns' pet has sniffed out cancer in his owner even before her mammogram showed any signs. Max acted depressed and lethargic. The dog often sniffed at his owner's breast then backed off with a "sad look in his eyes," according to Burns.

She developed a small lump on her breast. But her recent mammogram did not show anything wrong with her breast. Burns consulted her doctor and after several tests, she was told she had nothing to worry about.

Her dog's strange behavior continued and Burns was sure that her dog was trying to tell her something burdensome. She went to her doctor again and requested for a biopsy of the lump on her breast. The results showed that the lump was not benign but cancerous.

Burns said she came back home, her dog no longer acted strange and acted completely normal. Max put his nose on her breast where the operation had been. The dog wagged its tail and his eyes looked happy. She said she loved her dog and owed the discovery of her breast cancer to it.

The story of Burns and her dog Max was featured in BBC Earth's "Secret Life of Dogs." The report said dogs can smell the toxic chemicals of cancerous tumors. They can smell the changes in the human body, and in the case of Burns, smelled the cancerous tumor in her breast before a mammogram detected it.

According to a study by the InSitu Foundation, dogs are 99 percent sensitive and 88 percent specific in "smelling" lung and breast cancer in their early stages. Dogs will only need to smell the breath of a person with early signs of cancer to know something is wrong.