Pet dogs keep their feet from freezing By Ella Davies Reporter, BBC Nature Two border terriers rest their paws (c) David Greaves Pets naturally avoid cold feet Dogs can keep warm on frozen ground, thanks to a specialised circulation system in their paws, say scientists. Researchers in Japan used electron microscopes to study the internal structure of domestic dogs paws. They found that heat was transferred from the artery to the network of veins, meaning that cooled blood could not return to the body. The system has been recognized in many other animals extremities, including penguins beaks and dolphins fins. The findings are published in the journal Veterinary Dermatology. Arctic foxes and wolves are well known for their adaptations that help them to regulate a constant body temperature in cold conditions. Arctic foxes have dense and rigid fur on their feet which keeps the pads away from the freezing ground The pads are connective tissue and fat which is more resistant to freezing They have a rete mirabile or wonderful network of veins in their feet and legs that works as a heat exchanger where cooled blood is warmed up to maintain a constant temperature Previous studies showed that the canines can keep the tissue in their feet from freezing even in temperatures of -35C. Dr Hiroyoshi Ninomiya and his team at the Yamazaki Gakuen University in Tokyo, Japan, set out to discover if this ability was also common to domestic dogs. Using electron microscopes, the researchers were able to examine the internal structure of dogs paws. They found that the very close proximity of the arteries to the veins in the footpad meant that heat was conducted from one blood vessel to another. So when blood in the paws veins cooled on contact with the air or ground, warm blood pumping from the heart - through the neighbouring artery - transferred its heat. The blood was therefore warmed up before it returned to the body - preventing the dogs body from cooling down, whilst also keeping the paws at a constant temperature. It is well known that penguins in the Antarctic have a counter current heat exchange system in their wings and legs to prevent heat dissipation and keep the body warm, said Dr Hiroyoshi Ninomiya.
Posted on: Wed, 29 Jan 2014 17:19:26 +0000
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