How do a dog's paws withstand the cold and snow? Science has the answer
flickr photo by pmarkham
Minding your pets comfort in the winter is important, right?
In weeks past, this premise has been the focus of at least a couple of posts that I've written, and with even a little effort and mindfulness, it's easy to keep your pets comfortable.
One post in particular — protecting a dog's paws with booties while they're outdoors — prompted a bit of discussion, and one very good question was posed to me on Facebook:
"I'm a huge believer in protecting dog paws and had a set of these — until I went to pick up poop with rubber gloves on and my fingers almost froze off. Ever since then, I don't use them because the rubber seemed to conduct the cold exponentially. Obviously dog paws are not the same as human fingers, but I'd imagine the cold conduction would be the same. What are your thoughts?"
The same thought had crossed my mind when it came to using rubber dog booties, which are my preference for good reason: they protect paws from the elements (crusty snow, salt, ice melter).
But in gauging each dog's behavior during and after our outdoor adventures, there was no indication that they were experiencing any discomfort from the cold, and now, we know why.
Researchers in Japan discovered that our furry friend's paws are very special.
To begin with, dogs' pads contain lots of fatty tissue. This area doesn't freeze as easily as other tissues, and the blood vessels in dogs' feet are arranged in a way that's unique: they let them serve as living heat exchangers — arteries in the paws are very close to networks of tiny veins, and these allow the transfer of heat from venous to arterial blood.
The research was conducted by Dr. Hiroysho Ninomiya and other scientists at Tokyo's Yamazaki Gakuen University. An electron microscope and four subjects were used to help do the study, which was published in the journal Veterinary Dermatology.
A "counter-current" heat exchange occurs like this: a paw is cooled by contact with frozen ground, and warmth from the arteries in the paw gets transferred to the tiny veins, called "venules." This helps keep the paw at a manageable temperature. It also warms the blood before it flows back to the body, which helps keep the dog's body temperature from falling too low.
This isn't an ability that nature has given to canines only. Other animals, like penguins and foxes, have it, too.
The information in the study suggests that dogs may have evolved in cold environments, but this doesn't mean that they should be left out in the cold, by any means. They still need protection and care.