As it has been crazy hot here in Chch lately we have been looking at ways to cool the dogs down (esp during the day when we are at work) and I thought I would pass this hint on to you all...
The best thing we have found is filling a 2L ice-cream container with water, dropping in a small bone/bit of meat etc and then freezing it overnight. The next day we give our dogs a meat iceblock. They LOVE it and I'm sure it helps keep them cool. Also very funny to see their reaction the first time...
Hope this helps someone!