All of India and neighboring countries consider cow dung to be obvious normal fuel. I'm sure Google images will give pics, but the most common way is to shape it into round cakes of about one dropping size, slap it on a wall and let it dry. These often need to be broken into smaller chunks during use. Two surprizing things are a) cow dung is so hard that it can be difficult to break if it didn't crack while drying, and b) the smoke smells good when burning, a bit like
apple wood. In Nepal I saw people drying cow dung better: They shaped it into narrow lengths about a foot or 18" long and maybe 2 or 3" square, much easier to use, and it looked like some people were mixing other dry fuel in such as
straw, rice husks or sawdust, that would be inconvenient to burn otherwise.
I don't think horse dung has that stickiness turning into dry strength like cow dung, but you should try! For fuel, you want it to dry as quickly as possible and not start composting.
First step is not to call it poo.