Dogs' Feet Studied: Heat Exchange System Researched By Japan Scientists

TOKYO (Reuters) - Ever wonder how dogs can walk barefoot in the snow? Now a Japanese scientist may have the answer -- an internal central heating system.

The secret lies in how dogs circulate their blood to prevent cold surfaces from chilling the rest of their bodies, according to Hiroyoshi Ninomiya, a professor at Yamazaki Gakuen University, just west of Tokyo.

The system uses warm, oxygenated blood to heat the cold blood that has been in contact with a cold surface before returning it to the dog's heart and central circulation.

"Dogs exchange heat at the end of their legs. Arterial blood flows to the end of their legs and then heats up venous blood before returning it to the heart," Ninomiya said of his findings, published in the journal Veterinary Dermatology.

"In other words, they have a heat exchange system in their feet."

Ninomiya studied a preserved dog's leg under an electron microscope and found that because of the proximity of arteries and veins in the foot pad, the heat in the blood carried from the heart to the arteries is easily conducted to the cooler blood in the veins.

This heat transference maintains a constant temperature in the foot pad, even when exposed to extremely cold conditions.

Dogs are not alone in having this sort of heat exchange system, which is shared by other animals such as dolphins, Ninomiya said.

But not all dogs thrive in the cold, due to refining by breeders seeking specific traits, he added.

"Dogs evolved from wolves, and so they still have some of that ancestry remaining," he said.

"But that doesn't mean that one should always go and drag around in the snow all the time. There are many varieties of dogs nowadays that are not able to stand the cold."

(Reporting by Chris Meyers at Reuters TV; editing by Elaine Lies)

Comments

[Cognocit]

01:53 PM on 02/28/2012

This is interesting, although identification of counter current heat exchange in the paws of dogs was published sometime in the 1970s. I believe the responsible researchers were with the U.S. Navy, but will need to find the original.

[New Ideas]

03:15 AM on 02/28/2012

This doesn't surprise me, when you consider the wolf packs that go out hunting in the deep snows of winter.

[June25]

07:40 PM on 02/27/2012

Years ago my friends dog Blacky would just sleep when it snowed outside and in the morning we would call out to him Blacky would just jump up out from under the snow.The dog loved water and snow.

[Jasmine Adamson]

06:57 PM on 02/27/2012

My hairless Chinese Crested does not like the snow one bit, not at all. It makes his feet cold, but he won't wear shoes...

[vetxcl]

03:50 PM on 02/27/2012

My gosh!! You know I was just wondering this very thing!!! Wow! Now I know!!! Thank you, oh thank you AOL!!

[victorzeller]

02:58 PM on 02/27/2012

Dogs are smarter then most people.

[RHR]

03:56 PM on 02/27/2012

My terrier just reminded me that, grammatically, your comment should use "than" instead of "then" in a comparative sentence.

[blurredmolly]

09:52 AM on 02/29/2012

yeesh.....

[SherrySue]

12:59 PM on 02/27/2012

I really hope dogs were not abused to study their feet!!!!

[vetxcl]

03:57 PM on 02/27/2012

Yeah. Those those glued-on velcro attachments for the doggie snow shoes are really nasty.

Dogs chew on them and get poisoned.

[BobbyNCorpus]

12:28 PM on 02/27/2012

Dogs walk barefoot in teh snow becasue they aint got no shoes. Governor of Alabama told me taht once and I never forgot it.

[YankeeCanuck]

12:35 PM on 02/27/2012

Good thing for them dogs it don't snow much there.

[BobbyNCorpus]

12:47 PM on 02/27/2012

lol

[vetxcl]

03:51 PM on 02/27/2012

A reasonable response to a ridiculous article.

[cottere5]

11:28 AM on 02/27/2012

Two of my three wienie children have been in snow, and they love it. They are like little bulldozers, pushing it in front of them with their chests. Then it is hard to get them back inside.

[mwmes]

10:53 AM on 02/27/2012

Our Mutt loves the snow, not only did her ancestors giver her a double coat, but she also has a lot of fur between her toes. She also loves it when my kids build a snow fort in the front yard. She can jump out and scare the neighbors as they walk by.

My dog is smarter than your Honor Student. :)

[Coma]

11:41 AM on 02/27/2012

Yeah, but my Honor Student unexpectedly brings home Mexican food sometimes... bet your Mutt can't do that!

[victorzeller]

02:59 PM on 02/27/2012

Your honor student doesn't use napkins.

[vetxcl]

03:52 PM on 02/27/2012

Go back to sleep or get your honor student to interpret the article for you.

[vetxcl]

03:55 PM on 02/27/2012

Right. Because when you're smart you grow fur between your toes?

It's nice that you like a breed of dog that's adapted to a specific environment over many generations, but try not to read too much into it.