DD and I had guinea-pigs (before the cats) and it was a lot of planning to keep them cool -though I never had to deal with 40c
hutches are insulated due to being made of treated wood . They are woefully small with no room for 3 hops or standing upright (for rabbits)
The were popular in the times that rabbits were meat animals , you could keep them secure and starve them for an empty digestive system.
Most prey animals don't want to lie out in the sun, they hide . They need hay 24/7 . I gave our guinea-pigs solid hay or stuffed into looroll tubes so they didn't burrow in it . They'd have newspaper and shredded paper or equine card bedding
Ours had an amazing PiggieShed with removal windows (re-inforced where the space was to protect them) and a fan. They had hutches onto the floor space (so hutches just for sleeping in)
Theres loads of info on dogs , its in the news every day at the moment . None I've seen on small pets
They hide being ill , they won't shout or make a fuss , they will likely go into protective shock and die
Its a horrible way for them to die
But while there are Petshops and Gumtree "Great pets for the kiddies or cannot give them the time looking for 5* home" people will buy them without much thought of the pitfalls
And if your pets are out emjoying some late night crepuscular activity - remember the foxes are out too .