When it comes to accurately diagnosing a disease, you might think you need expensive, high-tech machinery and equipment capable of looking deep beneath the skin at what’s going on in the body. But while these high-tech implements certainly are incredible, they aren’t the only instruments capable of detecting disease. In fact, you may even share a home with one of these powerful disease-detecting agents.

There are numerous of instances of unsuspecting pet owners learning they had a health problem from their pet. Examples include dogs licking, sniffing and even trying to chew spots on their owner’s skin – spots that were later diagnosed as malignant melanoma.

In fact, many species of animals – from the microscopic worm C elegans, to ants, mice and dogs – have all successfully demonstrated the ability to detect diseases in people and from biological samples during experiments.

Many species (including dogs, rats and bees) can detect very subtle changes in substances called volatile organic compounds (VOCs) that the body releases in very low levels, even when healthy. In fact, exhaled human breath contains approximately 3,500 different VOCs. The composition and concentration of VOCs the body releases changes based on a person’s health – and will be different if they’re fighting an infection or dealing with a health problem.

The disease-detecting abilities of animals aren’t just for human benefit, either. The worm C elegans can not only detect cancer in human samples, their superior olfactory senses mean they can also detect cancer in samples from dogs and cats.