Is houseplant toxic to a lab?

I have a rubber plant in the house and our dog spence has grabbed a leaf or two off of it and has been chewing on it. I was just wondering if it were a toxic plant or it is okay? He only does it cuz he knows it aggravates me!

http://www.angel-litemaltese.com/Poison.htm

He does not do it with the purpose of aggravating you. Dogs' brains aren't complicated enough to make such a thought process. Better keep it out of his reach.