Why can dogs walk on cold ground?

THAT'S THE WHY:When I was growing up, it struck me that our dogs never minded running around in the snow. If you or I went barefoot on snowy or icy ground, the cold would soon cause severe discomfort.

But the canines didn’t seem to have that problem, and a recent study suggests their tolerant paws share characteristics with animals that live in chilly climes.

Researchers at Yamazaki Gakuen University in Japan used electron microscopy to analyse the structure of blood vessels in the footpad of a domestic breed of dog, and saw that veins surrounded and ran parallel to an artery.

This close arrangement means that as warm arterial blood flows towards the footpad, heat can get transferred to the venous blood as it flows back from the footpad's surface, note the researchers in the journal Veterinary Dermatology.

In practice, that would mean the heat transferred from the arterial blood gets conserved rather than being lost through the paw to the cold environment.

Penguins, whales and seals also have such “counter-current” heat exchange networks in their feet, fins and flippers to help avoid losing body heat, they add.

And there’s more: the study suggests the architecture of the vessels in the dog’s footpad could also promote the retention of some warm blood there to protect against tissue damage from the cold, and the nervous system can regulate the flow of blood to the area depending on the need that suits the environment.