In the early 20th century, coal miners in the UK took caged canaries into the coal mines to warn them of the presence of toxic gases such as carbon monoxide and methane.
The canary, being more susceptible to the toxic effects of these gases than humans and any other animal, was an excellent candidate to be a sentinel of sorts in the coal mine.
These days, many households have pet dogs as companions. They live in close proximity to their owners, often sleeping in the same room and travelling together.
This also means they have the same shared exposure to household carcinogens and outside risk factors.
Thus, the health of dogs may reflect that of their owners since humans and dogs suffer from the same spectrum of diseases.
In addition, dogs have a shorter lifespan than humans.
This means that chronic diseases, such as environment-induced cancer, appear faster in dogs, which may help predict the future health status of the pet’s owner.
In the 1980s, dogs in Philadelphia in the US, were used to provide an early diagnosis of mesothelioma (a form of cancer of the lining of the lungs, abdomen or heart) in humans.
Asbestos is often the cause of human mesothelioma and the latent period for cancer development after exposure is usually more than 20 years.
But in dogs, the latent period for the development of mesothelioma after exposure to asbestos is less than eight years.
Thus, pet dogs with spontaneous mesothelioma were used to identify owners who had been exposed to asbestos and had a higher possibility of developing mesothelioma.
On another occasion, a case-control study carried out at the University of Pennsylvania in 1989, revealed the relationship between canine bladder cancer and insecticide exposure.
Later, it was concluded that even in humans, the risk of developing bladder cancer is higher when exposed to insecticides.
Research has proved the ability of a dog to be a guardian for the cancer risk of their owners. Thus, proper yearly cancer screenings for pet dogs might save the owner’s life.
Dr Sujey Kumar, a lecturer at Universiti Malaysia Kelantan’s Faculty of Veterinary Medicine, volunteers in animal shelters and clinics. This article is a summary of his observations of the link between the health of dogs and their owners.