Scientists may have unravelled one of the big mysteries about dogs – why are our our four-legged friends’ noses so cold?
Previously, many believed that dogs’ chilly noses were to do with regulating the animals’ body temperature – but dog noses are actually heat detectors, it turns out.
Researchers found that dog noses can detect the presence of weak heat sources (such as small mammals) from up to five feet away.
Dogs can detect heat sources too weak to be felt by human hands, the researchers found.
In the study published in Scientific Reports, a team of researchers from Sweden and Hungary found when the ambient temperature is 30C, a dog’s rhinarium – the bare end point of the nose – is some five degrees cooler.
If the outside temperature is 0C, a dog’s nose will be around 8C. The two factors equal out at 15C.
Such differences suggested the tip of the nose served a sensory function – and in experiments, dogs could detect thermal radiation in double-blind experiments.
The research team from Sweden’s Lund University and the Eotvos Lorand University in Hungary studied three dogs – Kevin, Delfi and Charlie – who were trained to identify which of two identical four-inch wide objects had been heated to around 12C warmer than room temperature.
“All three dogs could detect stimuli of weak thermal radiation in double-blind experiments,” the study said.
The researchers wrote: “In addition, we employed functional magnetic resonance imaging on 13 awake dogs, comparing the responses to heat stimuli of about the same temperatures as in the behavioural experiment.
“The warm stimulus elicited increased neural response.
“All stimuli of radiating heat used in our experiments were too weak to be felt by human hands, even at very short distances. We had to touch the surfaces to feel the warmth.”