A dog x-pen is what I used for my outdoor brooder. Love that old thing! I did use my large for my show dogs, simply because at the venues I could set it up easily outdoors, walk my dogs out and put them in it, tell them to “potty”, then bring the dogs back in. I also used it as a puppy whelping area so babies could socialize well with household activities yet be safely confined. But to use one full time for most dogs, um, nope!
A skirt of hardware cloth around the bottom to keep chicks from squirting out, a couple of portal doors to facilitate integration, and they are absolutely the perfect brooder!!! In fact, as our 4th batch of chicks went out to live at a couple of days old, I remarked to my hubby that the manufacturers had missed marketing to a huge consumer group by relegating these things to one use!