Hi there Donnigan
 
While it is currently winter here in Aus, it does get quite hot and humid in summer.  A few things I do to help keep them cool and hydrated are:
 
* Watermelon is always a favourite in summer and helps with hydration.
* I put frozen vegetables into water, again helps with hydration, cools the water and the bobbing for treats entertains them and hopefully takes their mind off the heat.
* As they do not like getting wet, I damp down the dirt in their shaded run and they seem to like to lay on the cool dirt.
* Or, if they are free ranging, I spray the vegetation in their favourite spot which not only helps the vegetation but keeps that area cooler and the water has a trickle down effect from the vegetation.
* I also damp down and/or create puddles in frequently used paths etc, which they walk through and hopefully aids in keeping them cooler.
* I do have a mister system set up on the run but only use that in extreme heat because we already have enough humidity and adding to it could encourage mould spores which can result in respiratory issues.
* If someone is showing symptoms of getting a little too hot, I have damped down her face, wattles and comb.