I have a 45lb pittie mix with awful separation anxiety. He goes insane and tears everything up when he is left alone. I work at the shelter that he was adopted from, so I know that he was abandoned in his crate and he has intense anxiety when being in one, and we worked for months to get him super comfortable being in his crate in general, but when it came to being left alone he was like Houdini and would always manage to escape no matter what we used (crate locks, carabiner clips, crate cover, etc). I got him the 40” size and not only has he not been able to escape, but I genuinely think he has much calmer in this crate as well (most likely from the den-like feel of it). I have a camera that I use to check in on him while I am away and every time I check in he is sound asleep, whereas he used to freak out so much that he would scoot his previous crates around the floor and dent the metal in them. The only downside I can say to this crate is that it arrived with a bit of a dent in on top, but that hasn’t seemed to have affected the durability or function of the crate. Beyond happy!