Wednesday, June 19, 2013

Dogs and Heat. It's that time again.

As the temperature began warming up at the dog show, I once again saw all the people dragging out the fans for their crates.  And once again I become frustrated about this situation and want to lecture everyone on fans, dogs, and physics.  So I will take out my frustration on you.   I'll start with the physics.

First fact.  Fans do not cool.  What fans do is create a “wind chill”  By blowing air around, the fan makes it easier for water to evaporate into the air, carrying energy with it.  On people, the moving air evaporates sweat, and eliminates body heat.  The more evaporation, the cooler you feel. 

Second fact.  Unlike people, dogs do not really sweat.  They cool themselves through panting, blowing air across their wet tongue which evaporates moisture into the air, carrying energy with it.  However, there is little to no moisture on the rest of their body to cause heat loss due to blowing air.

1 + 2=hot dog.  Unlike people, blowing air across a dry dog does almost nothing to cool it off.  If you want to cool your dog off, you have to either wet the dogs fur (to create evaporation which will remove energy/heat) or, you have to place something cooler against them (like a chill blanket or ice pack).  Simply blowing the same temperature air across the dog does not have the same cooling effect that it does on a person.

Teeny tiny disclaimers.  There is a very small amount of heat that will be lost through convection alone if the air is cooler than the dog’s body temperature, and the air is blowing on their skin (not fur). However, this is so small, it is almost not worth mentioning.   Also, if the dog is in an enclosed area, like a crate that is completely covered, and their own body heat raises the temperature inside above the air temperature outside, then there is some benefit to moving the outside air into the inside.  But still, this is not cooling the dog.
If you want to test the concept, try this.  Get out a clean dry towel.  Feel the temperature of the towel against your hands/face.  Now twirl that towel above your head for 20 seconds and feel it again.  The temperature should be about the same.  Now take the towel and get it wet with room temperature water.  Wring it out good and then do the twirl.  Compare the temperature of the wet towel before and after.  It will have cooled significantly.  This is how a fan cools you (you're the wet towel) and doesn't cool your dog (he's the dry towel).
But there is a very easy solution to cool your dog-turn him into a wet towel!  When you turn on your fan, add a source of moisture to your dog.  You can mist him with a squirt bottle, or wipe him down with a wet towel.  If it is super hot, wet down his entire body.  There are even fans available that have a source of moisture built in.  Just remember, that the fan alone does not cool him!


1 comment:

  1. Great info, thanks! I've often seen owners use fans for their dogs at agility trials and wondered if it was worth investing in some for mine. I've been lucky so far and haven't attended a venue that was hot enough for the dogs to need cooling, gotta love AC!