I’ve got some work to do for a dog run. There are multiple runs inside a metal building with access to outside. There is two walls that are inside the run needing to be replaced down to the studs. What would you attach that’s water proof and will stand up to dogs. Currently there is Sheetrock with a think frp panel glued to it. But the dogs destroyed that.

I used concrete blocks called El Peso tiles.

Welded wire panels framed with round or square tubing

If the dogs are trying to eat it, I'd just use barn tin. Cheap(ish), waterproof, chew proof.

Forty five years old.

Due to the potential for Chagas, I would consider modifications that allow you to screen or close off the kennels. While the bug is much more prevelant in South Texas, It has been found in the Garland area. https://dfw.cbslocal.com/2014/10/30/north-texas-kissing-bugs-carry-potentially-killer-disease/ I've lost 3 dogs to Chagas, had
treated 5 others. Dogs kept in unscreened outside kennels are especially vulnerable.