So many "remedies"!
I don't claim to know it all, but lets look at some facts I do know.
First, chickens don't sweat...like dogs and other animals that don't sweat...they don't lose electrolytes through sweating!
Adding all these concoctions will also add a lot of salt and sugars!
Stick with supplements made for chickens!
Adding tasty frozen treats is a good way to get them to intake liquids and some nourishment.
When the temperature rise, animals slow down, and pant to pass air over their little ''radiator'' ...the tongue and mouth to cool them down!
This is similar to the basic principle of the "Swamp Cooler".
I have heard, if you (or someone) soak an overheated dog, they can go into shock!
Offer your chickens the opportunity to mist to cool down, don't force it on them.
Odds are they will Lay or stand in the mud!
In the past I have raised dogs, chickens, racing pigeons and various other animals.
Besides shading your coop and run, the Swamp Cooler is the THEE most effective way to help your animals survive inclement temps.
For pigeons, they're more hardier than chickens, I've hung wet burlap sacks and fans.
Works good.
Even just a box fan works..., they'll stand in front of it and open their wings to cool off.
When I used to raise as many as 200 chickens for food and profit, the best method is the Swamp Cooler, an old car or truck radiators, filled with water and put box fans behind them...the chickens would crowd around it!
Easy to make or they are offered commercially.
The birds don't get wet, neither does your coop!
.Another method I've used is a heavy old cotton towel, leave a few inches in a long pan of water, clip the other end over the top of the box fan...and let the towel act as a wick! Occasionally wet the whole towel, then let the fan blow on it. But you know how chickens are, soon they'll be jumping all over it, so you'll have to fence it off.
Do what works for your chickens, or go look at what works for large commercial chicken ranches.
Sure, they're not raising pets, but they do want to minimize their losses.
Nothing but fans! Some with Swamp Coolers...most just HUGE fans.