Call me naive, but I find this a bit implausible:

Inland Fisheries and Wildlife has issued seven permits in Maine allowing people to keep mountain lions as pets. But Kemper suspects they only hint at the true numbers. "There are a number of people who own mountain lions without permits," he says. Among them: "Remember the guys who were into drugs and kept pit bulls to protect their operations? Well, from what we hear they are now seriously into mountain lions."

It's possible, of course, but doesn't this seem like way more trouble than it's worth? Training a mountain lion to serve as an effective guard sounds difficult.

Photo by Flickr user deadeyebart used under a Creative Commons license