That is what I found out when I looked at Trex and some of the other plastic composites. No lumber store within a 50 mile radius carried even a small inventory of any of the composites so I had to replace my three decks with pressure treated. In hindsight I really don't like the look of the plastic composites and I am glad I went with wood. It would make more sense here in western WA with the endless rain we get though and eventually my low back will not allow me to be replacing wood every ten years.
Our choc lab has an entire fenced acre all to herself and she can trash it all she wants and I don't have to fix anything. Most of it looks like the surface of the moon along with a couple 4' deep caves she has dug out.
I can only imagine what a couple full sized dogs can do to a deck.