Small Pets

[Blueberry]

But it gets very hot inside a tent in the summer.

This. Plus - think of it from the pet perspective. You likely wouldn't take said animal out of its cage while camping (risk of running away - this could cause problems with cage cleaning), so you're taking it out of its comfortable environment, petrifying it, baking it, and keeping it locked up.

Of course, with a dog you would have to plan as well (petsitter, etc).