If you cover a dogs back with a wet towel you are effectively sealing in the heat. It's better to get them into a bath of water up to their arm pits or lay them on a wet towel.
Sounds like wee Rascal recovered fine though.

It's a worry, but we all welcome the sun, so just have to be careful - for ourselves and our children too I guess.
Mine were hot last weekend too - and jumped into my newly made pond - stirring up the mud that was just beginning to settle.

Think I'll have to fence it off. But then it
is handy for doing water retrieves I must admit