Is sweat from exercise different from that due to anxiety or illness?

Is sweat from a different cause – such as exercise, anxiety or illness – chemically unique? Can dogs tell the difference?

Claire Guest,

Medical Detection Dogs, Milton Keynes, UK

In short, yes. Sweat is mostly composed of water, but it also plays a role in the excretion of toxins and waste products from the body.

These substances can be hormones, minerals or volatile organic compounds (VOCs) produced as a by-product of disease. They can vary from person to person and depend on the cause of perspiration.

For dogs, which possess up to 300 million olfactory receptors, sniffing out the difference can…