I was on a dayhike in Boise today, up in the foothills above town. I came across two bike cops and a lady who had lost her Pit to a Cougar.
She was hiking with the Pit on a leash and the Coug came out of the brush, grabbed the Pit and shook/broke it's neck and drug it off right in front of the terrified lady. She said that the dog didn't even have time to fight back, and that she didn't dare try to fight the Cougar off.
They have been building home further and further up in the hills the past few years and more deer and Cougar have been coming down.