good chadderbank so it doesnt matter much 1) if I'm wrong and 2 ) no one understands what the hell I am on about. two things
body heat of dogs - hair is hollow and a good insulator. Scott of the Antarctic's dogs had lots of hair sticking out at right angles - a bit like a bottle brush. I hugged a malamute around the corner and it sort of went in 75% and I said the the dog - "fluffy hair and not much of you".
And the dog said - we're quite thin really with really thick layer of hair. Definite bottle brush
but that leaves the paws - or should I say - shall we pause for the paws ?
People will have noticed they (dogs' legs) are long and thin ( cursorial specialisation = they have evolved for running ) but the arteries are curled around the veins on the way down ( of the leg)
cue - counter current mechanism - at the top warm arterial blood warms the venous blood on the way back. Half way down, now-cooled arterial blood will still hear the really cold blood from the pad. At the pad really cold arterial blood becomes really cold venous blood ( independent of oxygen transfer ) - and this is the way that blood is conserved.
google 'why dont ducks feet freeze'
and also
http://en.wikipedia.org/wiki/Countercurrent_exchange
but there is only a paragraph on this
well it was a technical question
so expect a technical answer followed by 50 000 "wha ....'s?" 30 000 "mehs" and ten thousand 'yeah wha' yeaaaaah!'s
oh and you need specialised changes in the blood so that it works way off the standard temperature of 37 'C and doesnt sort of sludge