I purchased my kennels in 2012 and had a few of these crack over the years. I don't think a dog broke them - they just cracked. I purchased a couple replacements and the new ones seem to be a different material. They are smooth and more bendy (less brittle). They are also slightly thicker. It was a pain taking apart my kennel in order to install the new ones - since you have to unbolt EVERYTHING. but it seems these new ones will last longer.