Dog Feet Have Special Blood Vessels That Protect Them From Cold

Woof, it's cold out there! So how come dogs' paws don't freeze up when they pad around on snow and ice - and what keeps dogs from minding the cold?

Japanese scientists say they've discovered why. First of all, they say in a new study published in the journal Veterinary Dermatology, dogs' pads contain lots of fatty tissue - which doesn't freeze as easily as other tissues. And the blood vessels in dogs' feet are arranged in a way that lets them act like living heat exchangers: arteries in the paws are very close to networks of tiny veins (venules), facilitating the transfer of heat from venous to arterial blood.

When a paw is cooled by contact with frozen ground, warmth from the arteries in the paw is transferred to the venules. This helps keep the paw at a tolerable temperature. In addition, it warms the blood before it flows back to the body - thus helping keep the dog's body temperature from falling uncomfortably low.

The so-called "counter-current" heat exchange mechanism sounds like a good one, and it's not unique to canines. Similar systems are seen in other animals, including penguins and foxes, physorg.com reported. The finding suggests that dogs may have evolved in cold environments.

Research has shown that dogs' feet are protected from freezing even in temperatures as low as -35 Celsuis, according to the BBC.

The research, carried out by Dr. Hiroysho Ninomiya and colleagues at Tokyo's Yamazaki Gakuen University, was conducted with the help of an electron microscope and four willing dogs.

Comments

[helenfred]

12:25 AM on 01/19/2012

Counter-current heat exchange systems are, for example, essential in marine mammals, pre-cooling blood as it approaches the surface of the body, and pre-warming blood as it goes from the surface to the core. Elegant, efficient, pretty common. So efficient that many such mammals have to go to the surface to cool down.

[philips0811]

03:40 AM on 01/16/2012

I think that articles about dogs breed a larger variety of posts than any other. People have strong opinions about dogs.

[Cat-Lover]

08:36 PM on 01/15/2012

It seems God did a better job protecting dogs from extreme weather than he did man.
I wonder what evangelicals have to say about that?

[justgigging]

02:40 AM on 01/16/2012

Probably.......go shave your cat....lol

[FEsrigoHL]

03:46 PM on 01/16/2012

God had nothing to do with it. Dogs are extant due to MAN. The particular genetics of the wolf enabled man to choose what to keep & breed, directing & enhancing evolution to develope a dog that could perform the duties the men needed help with. In northern areas dogs had to live & run out of doors. No dog with thin pads & the inability to withstand the cold lived or was used for breeding. This is elementary knowledge in farm areas. You want chickens that lay a lot of eggs, then you keep chicks ( both hens & roosters) from the hens that lay a lot of eggs . MOST people are TOO lacking in knowledge about genetics & dogs; despite how important both of these things are to most people. Working from opinion & emotion ( most people) is COUNTERPRODUCTIVE & leads to NO understanding , improvement or understanding: FACTS & REASON DO. Please use the latter. www.AKC.org

[Cat-Lover]

05:50 PM on 01/16/2012

Regardless of how, evolution, with or without man's involvement, dog's got to where God would like man. Even better!

[FEsrigoHL]

09:16 PM on 01/16/2012

You are entitled to your own beliefs; BUT this is not a religious site. Lets stick to the subject & facts. Wading thru that bigoted humane extremist is already more than I care to deal with. However, because her area has so many low down people gives her no right to besmirch the reputation of people of my caliber. She is treating the symptoms & not the disease. She should be getting legislation passed to stop puppy mills, puppy farms & back yard breeders & the auctions, plus the pet shops. Then she would make a real contribution to the welfare of dogs. As long as those slime balls stay in business she will be up to her butt in dog problems.
If you have a hole in the dike, more & more catch buckets won't solve the problem. The hole needs to be plugged. My breed is a companion/protector for the family. They are structurally & tempermentally superior due to my diligence in keeping only really good females & breeding them to really good males. They are known around the world & in many books. I can only do my part.

[OdinsEye]

02:59 PM on 01/15/2012

My experience with several pets and hunting dogs would lead me to believe that this is going to vary depending on the dog breed. For example, we had a Lhasa Apso who absolutely loved the snow and except for the snow dredlocks she would get never seemed to have a problem. The little Min-Pin we had, on the other hand, could not tolerate the snow and would immediately lift her paws.

[FEsrigoHL]

03:54 PM on 01/16/2012

Yes, & on who the breeder or producer is. Producers breed anything for profit. Real breeders
aim to develope a line of dogs with superior qualities. Of course the breed is a major factor. Lhasas come from a COLD country & have lots of HAIR. Min Pins are short haired without undercoat & are not expected to brave the elements; so are not chosen for cold tolerance when evaluating them for possible breeding. The breeds used to develope the Min Pin also affect the breed today. I owned & bred Min Pins in the past. NO sensible person hunts & breeds a Lab that can't deal with cold water & bad weather.

[IMissAmerica]

02:58 PM on 01/15/2012

Thanks for this! I walked barefoot on my lawn on a sunny day in November and practically fainted it was so cold. Was wondering how the frozen ground seems not to bother the dogs.

[escribacat]

01:04 PM on 01/15/2012

I use musher's grease on their paws when it's really cold. If it's too cold, my dogs let me know by lifting their paws. If it's around 15 degrees or less, they always lift their paws. I don't believe that -35 degrees number!

[Watching rock grow]

01:17 PM on 01/15/2012

I believe your dogs know you to be a softy and are playing with you :)

[Phyllis Copeland]

06:53 AM on 01/16/2012

That is a possibility! My significant other said they had a dog growing up who came to live with them when they lived in Pensylvania, so when the dog went outside in the winter, he would come stand at the back door and shiver and be let in. A couple of years later, they moved to Florida, and wouldn't you know that dog would stand at the back door in 90 degree weather and shiver to be let in!! We laugh about it all the time, but I can't help thinking Pavlov really knew his stuff!! :-)

[Jim chaos]

12:21 PM on 01/15/2012

So how did they determine that -35 degrees was near the limit for dog paw freezing?

[FEsrigoHL]

04:03 PM on 01/15/2012

People living in areas with lots of cold weather only kept dogs that had the type of constitution that tolerated cold weather & used them for breeding. After multi generations the tolerance increased. This is EVOLUTION.

[usernamealreadyinuse]

11:21 AM on 01/15/2012

I am so lucky that I have the same type of system working for me although in my hands and other extremities.I live in a ski resort and I have not worn a hat or gloves for over twenty years when I downhill or cross country ski.People think I am crazy when I ski in minus twenty degree or even colder conditions.My hands and ears have never frozen although the ski patrol warns me all the time that I am in danger of that happening if I don't cover up.It has been this way since I was a kid and I believe the body of any animal including humans will adapt in time to adverse conditions when allowed to.Running for cover and putting on too many clothes will only weaken a person's tolerance.Exposing some skin consistently to the elements just increases the tolerance.
I am certain that the vascular system creates more and more venules in those areas that are threatened.I am very aware that I also have living heat exchangers and I can feel them working for me.There is a distinctly warm glow pulsating through my skin which feels as if a mini furnace has been switched on.I would never suggest anyone try this approach without starting when they are very young as it takes a lifetime for it to be that effective.

[FEsrigoHL]

04:05 PM on 01/15/2012

Such tolerances are genetic, otherwise everyone who grew up in cold areas would have the same tolerance.

[Phyllis Copeland]

06:56 AM on 01/16/2012

Are your ancestors from cold climates, like Sweden or Norway? It could be adaption from severl generations of family members living in extreme cold.

[hoosierhelen]

10:53 AM on 01/15/2012

We brought our little short haired dachshound to Indiana from Florida 4 yrs ago as a puppy. To our amazement he absolutely loves the snow. He rolls in it and pushes his face down into it. It is hard to get him out of it. He does not like walking on ice or walking on a rainy day. If it is raining outside, he won't move off the steps. If he hits a patch of ice, he is off of it immediately. When the weather gets down around zero, he takes care of his business and shortens his walking time considerable. (thankfully) I believe different dogs handle the cold differently and these scientists must not be dog owners.

[escribacat]

01:05 PM on 01/15/2012

Agreed. My greyhounds love the snow but not when it's snowing and not when it's too cold out. I take in rescued greyhounds from Florida and it's really hard to house break them in the Colorado winter weather.

[FEsrigoHL]

04:06 PM on 01/15/2012

hounds & small dogs are, in general harder to housebreak.

[Phyllis Copeland]

06:57 AM on 01/16/2012

Dachshounds were bred in Germany which has famously cold and snowy winters, so your little dog may have found his ancestral climate! :-)

[Roadrun]

09:38 AM on 01/15/2012

Okay, so now explain why a lab is so happy with icicles all over it's body when it climbs out of water on a 9 degree day? I swear they are more happy then that at any other time in their life.

[mykirbyroo]

02:22 PM on 01/15/2012

Your lab is a comedian. They are so funny! One of the happiest dog breeds there is! I swear if they could laugh, they would. Lucky you to share your life with one!!!

[Roadrun]

03:34 PM on 01/15/2012

They have two moods - 1) I didn't mean to 2) now that we have that worked out, throw the ball again.

[FEsrigoHL]

04:08 PM on 01/15/2012

Again, genetic. Dogs who wont jump into cold water to retrieve were not kept or used for breeding when the breed was being developed. It is called EVOLUTION>

[Roadrun]

04:13 PM on 01/15/2012

I don't know if it is evolution or what it is but I am certain that you don't have dogs.

Oh, what do you imagine my dog is retrieving from the water? Icicles?
It's called having fun.

[FEsrigoHL]

06:01 PM on 01/15/2012

Of COURSE its evolution. REALLY. It so happens I am a professional BREEDER ( NOT commercial producer). I am in all the books on my breed, am known around the world for the excellence of my dogs. SO THERE !! I have the rep for knowing the right dog to breed to in order to produce the best quality dogs. I have the desire AND ability for this field. I also am a superb handler & able to get the best performance from a dog in the show ring. I do my homework by studying pedigrees & observing what various studs are producing in the US & Europe.NO, I'm NOT rich but I put everything into the dogs from my business, which is NOT selling dogs. You do NOT speak from knowledge, but opinion; which all know everyone has, the same as all have a rear end.

[kwestionauthority]

09:28 AM on 01/15/2012

I live in Vermont and I've given homes to fifteen rescue dogs in the last twenty five years. Many ot them--even collies with thick coats--came with frost bitten feet. This article is irresponsible and should be deleted. It will only hurt dogs.

[Donnie DeVun]

03:34 PM on 01/15/2012

The article isn't suggesting leaving your dog out in the cold; it's simply suggesting a mechanism by which the pads of dogs' feet avoid freezing. Censoring scientific research simply because some people might get the wrong idea is just wrong.

[kwestionauthority]

02:02 PM on 01/16/2012

Good writing does not invite misreading.

[reality4u2]

08:30 AM on 01/15/2012

My dogs must have gotten people feet - they won't walk more the a few feet on snow without picking their paws up and looking to get back in the house.

[Warren Yuill]

09:23 AM on 01/15/2012

When I put mine out on a rainy day they act like they are walking in battery acid. For the first little while anyways. Then they come back in slathered in mud and quite happy.

[mccudds107]

10:12 AM on 01/15/2012

make sure its not the ice salt you put on the ground it burns their paws

[reality4u2]

10:26 AM on 01/15/2012

Thanks, appreciate that, but I don't use any ice salt for that very reason and we don't walk on the road. It's funny as I have three little guys and one (10 years old) is very sensitive to the cold/snow on his feet, the other (same age) only after being out for a while and the 14 month old is too busy running around on the golf course (I'm on a fairway of a 27 hole course) to care...

[Sandy Bos]

10:09 PM on 01/14/2012

. . . with the help of "four willing dogs". Really? Exactly who asked them? Did they sign a liabllilty release? Vivisection is alive and well. In addition, exactly what breed(s) did they experiment on? This article is so generalized that it is of no use. Do you mean to infer that a Yorkie can with withstand the same temps as a Malmute? Dogs DO mind the cold. They are bred to be domestic house pets. A worthless article and "study" at the expense of, of course, the animals.

[FEsrigoHL]

04:25 PM on 01/15/2012

Only ignorant, uncaring people breed dogs as housepets unless they were originated for that purpose. Then all bets are off & you need to provide an area OUT of the bad weather to exercise them; otherwise you are being cruel. Most breeds originated for a working purpose & have a written description of how they should look & act & move, etc.. THAT is what dog shows are for : to reward those dogs that come closest to what they should be to do their job. They are breeding stock ( and can be house pets too). Those that are NOT of show quality should be sold as PETS with LIMITED REGISTRATION & NOT bred. To PRODUCE pups from such dogs is irresponsible. The resulting pups are the ones that are most likely to end up in shelters. ALL reputable breeders require dogs not kept by the original buyer be returned to them : IN THE BILL OF SALE. 75% of all pure breds are NOT well bred & are PRODUCED by puppy farms & back yard breeders ONLY for profit. AVOID them. Only a book could give a thorough story on this matter. Going to a dog show will open your eyes & give a good selection of dog books. Do yourself a FAVOR & find a show listed on AKC.org thru Dog Show Superintendents.

[Sandy Bos]

09:06 PM on 01/15/2012

You are Clearly a breeder. FYI, dog shows have NOTHING to do with rewarding dogs that meet performance stds. If that were true, why check the topline? Where are the sheep? Don't we want to see the herding group, well, HERD??? What a joke. Regardless, I have no idea how your response relates to my post, but since you felt the need to reflect on it, I will reflect on yours. "Only ignorant, uncaring people breed dogs as housepets unless they were originated for that purpose." Really? When a Maltese is bred, what other purpose was intended? Regardless, "reputable breeders" is an oxyMORON. In addition, "papers" for a dog are laughable at best. You could paper a cockroach. I've been to 3 dog shows . . . nothing there surprised me. I have ZERO respect or regard for "breeders". Few adhere to the commandments of accepting a dog back, that they have bred & sold. Most "breeders" are trash, with ZERO regard for life itself, selling & dumping it off like a used lawnmower. I've rescued used up "bitches" from the breeder's auction. I know. Experiments on animals is wrong. Using animals for entertainment is just as equally narcissistic and unethical. And incessant breeding of animals, for which there are no homes, and of which the MAJORITY end up in harms way, also shares the same platform of greed. So, I'll pass on the AKC.org referal. I think as small of them, as I do Barnum & Bailey's.

[FEsrigoHL]

03:28 PM on 01/16/2012

YOU have REAL problems. PRODUCERS are not synonymous with BREEDERS. Yes, most pure breds are PRODUCED for profit. THAT is the fault of the buyers. If they did not buy from pet shops & puppy farms & back yard breeders, those people would stop PRODUCING dogs. YOU are SLANDERING the real breeders. I hope someone sues you. If you attended a dog show in Ohio or the like I'm sure you did not see the best dogs or people connected with them
A TOPLINE is VERY important. It transfers the propulsion from the rear to the front and enables the most movement for the least effort. There are herding tests & titles are given for the passing partisipants. You let your bad experiences overwhelm your manners & mentality.
I cant be held responsible for bad eggs. There are NO dog auctions in my area: those are in areas with low down people. When YOU close your mind you enable the bad eggs.

[grizzly bear55]

09:19 PM on 01/14/2012

I have 2 malamute dogs an they are my 3rd pairs, very large in the 150-160 LB, they feel the frozen ground when it's minus 25 Celsius and lower, they lift one paw at a time and keep switching paws down.

I don't know what these scientists are talking about.

[FEsrigoHL]

04:32 PM on 01/15/2012

Mals were originated to haul heavy freight in Arctic situations. CORRECT breeding will use only dogs who have NO difficulties with cold weather conditions. When they freight they do NOT stand still. They run, so any paw is not constantly on the ground. You need to be in touch with breeders who race Mals. They can give you the skinny on all things Mal. WWW.AKC.org will help you find REAL Mal breeders; NOT producers who only do it for profit & use incorrect dogs for breeding.

[TomMartin]

08:07 PM on 01/14/2012

Celsuis? Don't you have a spell checker software?

[FEsrigoHL]

04:32 PM on 01/15/2012

These sites do NOT have spell check

[TomMartin]

12:25 AM on 01/18/2012

If the Huffington Post writers have no spell check, then they should get a Mac like I have, it spell checks everything. Though if I write in a foreign language, almost everything is then underlined.