How dogs can walk on ice without freezing their paws

Jan 13, 2012 by Lin Edwards report
dog

Scientists in Japan have solved a long-standing veterinary mystery: how dogs can stand and walk for so long on snow and ice without apparent discomfort, and without freezing their paws.

Scientists at Tokyo's Yamazaki Gakuen University wondered why dogs do not seem to feel the cold in their paws, even though the paws have less insulating fur than their trunks. The paws have pads containing a high , which freezes less easily than other tissues, but they also have a high surface area-to-volume ratio, which means they should lose heat easily.

In humans exposed to frigid temperatures, vasoconstriction occurs in the extremities to reduce the blood flow and resultant , and ensure the blood returning to the rest of the body does not cool too much.

The research team, led by Dr. Hiroyoshi Ninomiya, used a scanning electron microscope to study the paws of four adult dogs, and discovered that the supplying blood to the pads had networks of numerous small veins, or venules, closely associated with them, and that the system essentially acts as a counter-current .

When warm blood arrives in the paws via the arteries, heat is transferred to the venules closely associated with the arteries, thus ensuring the blood has been warmed up before it returns to the rest of the body.

The counter-current heat exchange system prevents the body cooling and ensures the paw temperature stays within reasonable limits. The same system has also been identified in other animals such as Antarctic penguins, where it occurs in their legs and wings, and dolphins, which use a heat exchange system in their fins.

The Arctic Fox (Vulpes lagopus) was already known to have a counter-current heat exchange system in its paws, along with numerous other adaptations to the cold, but the existence of such a system in domestic dogs had not been previously suspected or identified. The findings suggest that domestic dogs might have originated in a , in which such a system would have had survival benefits.

Domesticated dogs are not all able to withstand icy conditions on their paws to the same extent, depending on their environment (such as habitually living indoors), and the breed. Common tips often suggested to help avoid cold feet in winter is to ensure their pads are not split or injured in any way, and to spray their paws with cooking spray before taking them out in the snow. Frostbite is very rare in dogs, but it can occur.

The paper is published in the journal Veterinary Dermatology.

Explore further: Rescued 'abandoned' penguin chicks survival similar to colony rates

More information: Veterinary Dermatology, Volume 22, Issue 6, pages 475–481, December 2011. DOI: 10.1111/j.1365-3164.2011.00976.x

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User comments : 39

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Henka
5 / 5 (6) Jan 13, 2012
Spray 'n Cook on doggie paws, yummy.
antialias_physorg
3.2 / 5 (6) Jan 13, 2012
The same system has also been identified in other animals such as Antarctic penguins, where it occurs in their legs and wings, and dolphins,

Not to mention all birds. Birds are able to sit on frozen wires or surfaces indefinitely because of this counterflow heat exchange mechanisms.

For dogs you can add the fact that they have only about 10% of the pain perception that humans have.

rawa1
3.8 / 5 (8) Jan 13, 2012
Some other organism use the same, just opposite principle of heat exchanger for maintaining their important organs warm and active. For example the predator fishes like swordfish and tuna have eye sockets warmer than the rest of their body surface for faster processing of visual signals, which gives them an advantage over their prey.
Deathclock
2.8 / 5 (10) Jan 13, 2012
For dogs you can add the fact that they have only about 10% of the pain perception that humans have.


Do you have a source for this info?
antialias_physorg
4.6 / 5 (9) Jan 13, 2012
Do you have a source for this info?


Just what a vet told me once about a particular breed of dog (but I don't remember which...Rottweiler? Pitbull? German sheperd? Something like that). I thought this was universal. But checking around I found that the pain threshold does seem to vary with the age and type of the dog.

The only thing I could find on short notice with any quantitative results (and which didn't require subscription to a journal site) was about shock collars for dogs which go up to 7500 Volts (for comparison: a bug zapper has about 2500 Volts and is something you really don't want to touch)
Deathclock
3.7 / 5 (13) Jan 13, 2012
Thanks, and also thank you for not taking that request as an attack against your statement and getting all defensive like a lot of people tend to do.
Dylan_Lee
5 / 5 (2) Jan 13, 2012
In teaching biology, whales are a model example for countercurrent exchange.
BillFox
4.9 / 5 (7) Jan 13, 2012
As the son of a veterinarian, I can tell you that your vet has misinformed you about the pain sensitivity of dogs.
Deathclock
3.2 / 5 (9) Jan 13, 2012
Yeah, I asked for sources because I know my dog acts hurt under roughly the same circumstances that I would... but that is anecdotal and based on simple observation so I was wondering if there existed more authoritative information about the topic.
Vendicar_Decarian
0.5 / 5 (42) Jan 13, 2012
Bullshit!

"For dogs you can add the fact that they have only about 10% of the pain perception that humans have." - Antialias
Skultch
5 / 5 (2) Jan 13, 2012
This is relevant to my alpine lifestyle and my wuss of a dog. haha commence anecdote:

I've got two mutt rescues, german shephard-ish and brittany spaniel-ish. The GS is a natural alpine backcountry companion in every way imaginable, including steep ski descents. He never complains about the cold on his pads or in general (healthy double coat). The BS, being bred for more temperate bird hunting, can't stand the cold. He usually requires a coat and booties for cold-snowy hikes longer than 30 minutes. It's not so much the cold on the pads, but the ice that collects in the hair between the toes. It just keeps building and the pressure is what hurts. Cutting that hair resolved the need for booties.

In the summer they both get booties for the sharp rocks, but that's only for 12,000 ft or higher climbs way above treeline.
xNico
5 / 5 (2) Jan 13, 2012
Do you have a source for this info?


Just what a vet told me once about a particular breed of dog (but I don't remember which...Rottweiler? Pitbull? German sheperd? Something like that). I thought this was universal. But checking around I found that the pain threshold does seem to vary with the age and type of the dog.

The only thing I could find on short notice with any quantitative results (and which didn't require subscription to a journal site) was about shock collars for dogs which go up to 7500 Volts (for comparison: a bug zapper has about 2500 Volts and is something you really don't want to touch)


The Voltage doesn't matter, it's all about the amps. If I shock you with something that is 100,000V and has .07A, you will survive, whereas you'd die if I shock you with something that is 20V and has 1A. It's all about the current.
Telekinetic
2.4 / 5 (13) Jan 13, 2012
The human garbage can, Mitt Romney, drove many hours with the family dog in a kennel on top of the car at highway speeds. That tells me all I need to know about him and his base.
HealingMindN
4.4 / 5 (9) Jan 13, 2012
The human garbage can, Mitt Romney,...


Do you have references to that "human garbage can?" I can only google references that he IS garbage.
trekgeek1
5 / 5 (2) Jan 13, 2012


The Voltage doesn't matter, it's all about the amps. If I shock you with something that is 100,000V and has .07A, you will survive, whereas you'd die if I shock you with something that is 20V and has 1A. It's all about the current.


If 70mA passed across your chest you'd probably die. It really matters where it touches you. At 100,000V and 70mA you'd be pumping 7kW of power into someone. You might die from the shear damage done to your tissue. 20 volts can't really pass through your skin. Your premise is correct, I am just commenting on the numbers chosen. I agree, current is what matters.
Deathclock
1.6 / 5 (5) Jan 13, 2012
Now I have to ask, say you kept the current constant at 10mA, but varied the voltage wildly from like 100v to 100,000v... would you even notice a difference?

I'm pretty weak with electricity, my understanding of voltage is that it is analogous to pressure in a water pipe where current is analogous to... well... current.
Vendicar_Decarian
0.4 / 5 (37) Jan 13, 2012
"The human garbage can, Mitt Romney, drove many hours with the family dog in a kennel on top of the car at highway speeds." - Telekenetic

If so he should be put to death.

References?
antialias_physorg
5 / 5 (1) Jan 14, 2012
I'm pretty weak with electricity, my understanding of voltage is that it is analogous to pressure in a water pipe where current is analogous to... well... current.

Current is directly proportional to voltage (given the same resistance). Assuming that skin resistance of dogs is not markedly different than that of humans (skin cells being more or less similar in land dwelling vertebrates) a similar voltage should cause an identical current.
Vendicar_Decarian
0.4 / 5 (37) Jan 14, 2012
"Assuming that skin resistance of dogs is not markedly different than that of humans" - Antialias

Dogs don't sweat from most of their skin, and have a layer of insulating oil secreted onto the skin.

Hence the conductivity will be lower.

Isaacsname
5 / 5 (1) Jan 14, 2012
Since some dogs that are typically from colder climes have hollow hairs( not all) wouldn't there possibly be a mechanism that excludes water from the folds of the pad by way of capillary action ?
Zilvar
5 / 5 (1) Jan 14, 2012
Does anyone have any experience with cut injuries in dog feet? Our dog cut his pad 2 weeks ago and it's still opening when he walks on it.
Telekinetic
1.6 / 5 (7) Jan 14, 2012
Read it and weep- this could be our next fearless leader:
http://www.care2....car.html
Isaacsname
5 / 5 (2) Jan 14, 2012
Does anyone have any experience with cut injuries in dog feet? Our dog cut his pad 2 weeks ago and it's still opening when he walks on it.


Veterinarians have extensive experience with that sort of thing..

*reaches for cheese danish*
trekgeek1
not rated yet Jan 14, 2012
Now I have to ask, say you kept the current constant at 10mA, but varied the voltage wildly from like 100v to 100,000v... would you even notice a difference?

I'm pretty weak with electricity, my understanding of voltage is that it is analogous to pressure in a water pipe where current is analogous to... well... current.


V=I*R

We have only three variables to use here. The voltage applied, the current and the resistance of the body. Your body would have a constant resistance (neglecting any weird effects) that would not change. The problem is that your scenario has defined all three variables, but you only have two independent variables and one dependent variable. You can't say "what would happen if the resistance was constant and the current was constant and you varied the voltage?" One of these must be determined from the others. For instance, I=V/R would allow us to see that increased voltage increases current with a constant resistance.
Parsec
5 / 5 (2) Jan 15, 2012
If I sprayed my dogs paws with cooking oil, he would plop down and lick every yummy bit off his paws before venturing outside. I suspect that having completely soaked paws would be somewhat less than optimal...
Vendicar_Decarian
0.4 / 5 (37) Jan 15, 2012
"Our dog cut his pad 2 weeks ago and it's still opening when he walks on it."

Call a vet.

Provide the dog with a sterile boot when it walks.

You may be able to very lightly tape the paw. Very lightly because you can easily do great damage to the foot if you bind it tightly and prevent blood flow. The result could easily be gangrene, amputation, death as the dog can't tell you if it is bound too tightly.

I would use a antiseptic boot to keep it clean, and try to limit the dog's use of the paw by bringing it food and water.

Keep it on the sofa.
KBK
1 / 5 (1) Jan 15, 2012
My personal experience with voltage and current comes from playing with direct handling of DC and AC voltages and currents --- thousands of times, barehanded.

The threshold (bare dry skin) is about 30V, and that's about it. On your tongue, for example, something wet, then conductivity is high.. and one gets uncomfortable quickly, at 5-10VDC. (like kids play with 9vdc batteries, on their tongue--a 12vdc wall wart is uncomfortable')

Due to the low conductivity of normal skin, ie, reduced conductivity, short term contact with 'voltage' is about 30-35VDC. Above that, conductivity increases fairly quickly and one 'notices' the current flow rather quickly..as a conductive pathway is established.

Higher potential causes the conductive pathway to be established quickly. Due to this sort of thing, you can have normally dry naked skin 'brush up' against 120AC, with only minor shocking.

Establishing conductivity is the real danger. I've been hit by over 400VACRMS. Total Blackout/shutdown.
Sinister1811
1 / 5 (5) Jan 15, 2012
For dogs you can add the fact that they have only about 10% of the pain perception that humans have.


I don't agree with that at all. Just because there's no way to measure it, doesn't necessarily mean that they feel less pain.
Palli
not rated yet Jan 15, 2012
Now I have to ask, say you kept the current constant at 10mA, but varied the voltage wildly from like 100v to 100,000v... would you even notice a difference?

You can make the hair on your head stand straight on end and not feel any pain if you apply high voltage across your body using only tiny current flow. This will not work at lower voltage and lower resistance (lower resistance bringing higher current). The effect of (high V, high R) and (low V, low R) will therefor have different properties at same total power levels.
Why this is I'm not sure, perhaps there's a threshold where electrons start flowing through the body instead of traversing around it, depending on body's resistance and conductance in air surrounding the body (amongst other variables), or maybe it's just that we can't feel the effect with such low current. This could be more accurately and better explained by someone more knowledgeable about electricity...
DunkMcForkin
1 / 5 (2) Jan 15, 2012
I have 5 dogs and can verify that they dont feel close to the same amount of pain that we do. A paw from a dog to the face hurts but it doesnt seem to hurt their dad near as much. Also they seem to have to ability to shut off pain and we do as well...just like we got the ability to harness the electromagnetic field with our brain and know which way is north like them foxes they did a recent study on in germany.
captainelectron
1 / 5 (1) Jan 15, 2012
"The human garbage can, Mitt Romney, drove many hours with the family dog in a kennel on top of the car at highway speeds." - Telekenetic

If so he should be put to death."

References?


I found many references with a Google search where Mitt Romney admitted in a Fox News interview treating his dog "Seamus" in a manner that no true dog lover would tolerate. This occurred many years ago.
Here is a link:
antialias_physorg
not rated yet Jan 16, 2012
The threshold (bare dry skin) is about 30V, and that's about it.

We did tests on ourselves at uni. It also depends on the frequency. DC gets painful since the induced ion flow will cause acid burns.

AC doesn't induce ion gradients, but it does stimulate nerves directly. It gets painful at middling frequencies (unfortunately the 50-60Hz range seems to be 'optimal' for causing pain), whereas lower ferquencies and higher frequencies seem to be less painfull until you crank up the voltage.

You can make the hair on your head stand straight on end and not feel any pain if you apply high voltage

For this you have no current flow. That's just static electricity (like in a capacitor). Rubbing a balloon against your hair and bringing it close to your body will do the trick. If you bring it too close you WILL get a current (nasty shock).
shwhjw
5 / 5 (2) Jan 16, 2012
...even though the paws have less insulating fur than their trunks.


The Japanese have to do EVERYTHING differently don't they? They've even managed to breed dogs with trunks!
Xbw
1.3 / 5 (15) Jan 16, 2012
The findings suggest that domestic dogs might have originated in a cold climate, in which such a system would have had survival benefits.


Domesticated dogs are descended from Gray Wolves. Of course some of the natural defenses against the cold carried over. http://en.wikiped...wiki/Dog if you dont like wiki, feel free to check other sources but they will confirm the same thing.

Also, on the issue of pain. I don't think it is so much a case of dogs not experiencing pain as we do. It more that they are less focused on it. If my dog runs into a wall, he yelps, then goes right back to chasing his ball. If I run into a wall, I curse, hit the wall, and go on to complain about it for 2 hours :)
Skultch
not rated yet Jan 16, 2012
I don't think it is so much a case of dogs not experiencing pain as we do. It more that they are less focused on it. If my dog runs into a wall, he yelps, then goes right back to chasing his ball. If I run into a wall, I curse, hit the wall, and go on to complain about it for 2 hours :)


Good point. Even if you can determine limits with tissue resistance and even if a neuron reaches the threshold, the subjective and relative psychological pain experience could be not directly related to what is happening to the neurons in the skin. I'm no neurologist, but I think the brain could ignore the signals after a certain amount of time or even ignore them until a minimum time threshold has been reached. Then, who knows what the dog brain decides to do with that info and if it's the same across all mammals. I don't know how to describe this physically, but in humans, context and expectations of comfort also have an effect on perceived pain. Is this different in dogs?
Xbw
1 / 5 (9) Jan 16, 2012
I don't know how to describe this physically, but in humans, context and expectations of comfort also have an effect on perceived pain. Is this different in dogs?

I would assume so. Dog's attention remains fixed on the moment. Unless the pain is immediate and constant, they will pretty much forget about it.
9999
1 / 5 (3) Jan 19, 2012
To antialias: You don't seem to understand electricity very well. The reason that touching an electrically charged object is generally a bad idea is that there is frequently a large amount of amperes available. High voltage in and of itself is NOT dangerous. Just scuffing your feet on a nylon carpet generates thousands of volts but almost no current. Therefore, touching the door knob releases a very high voltage without any significant damage to your finger. Volts times amps equals watts. One hundred thousand volts times one micro-amp equals only 1/10 of a watt. You may get the drift.
antialias_physorg
5 / 5 (1) Jan 19, 2012
High voltage in and of itself is NOT dangerous.

U=R*I
Skin resistance is fairly constant (Ok, it's a bit dependent of the frequency of the current but to a good approximation it's constant)

High voltage means high current at constant resistance. The reason that static electricity isn't very dangerous is that the time the current exists is very short.
Power is resistance times current squared (which is high). but total ENERGY conveyed is Power divided by time (since time is short this is rather low).

The wattage isn't what keeps your fingers from being damaged. It's the lack of Joules conveyed.

One of the reasons why 'lightning power stations' are not a good idea: the power is high, but the total energy gathered per lightning bolt is low.

You don't seem to understand electricity very well.

Since I hold a university degree in biomedical electrical engineering I'd beg to differ.
MP3Car
5 / 5 (1) Jan 19, 2012
We're way off topic here, the article was about dogs walking on ice. I'm an EE and would love to get into this discussion... but there's plenty out there on the web about this...