Dogs can also sense escape tunnels, although it isn’t quite as easy as that. They will scratch at the floor and bark a bit, but you need to keep an eye on them to notice this and perform appropriate searches within your jail. If they happen to be scratching the floor when there is an actual prisoner digging directly under them, the prisoner is rumbled and the whole tunnel is revealed. We suggest you create long patrol routes around the perimeter of your jail and assign dogs to these, to keep a handle on your escape tunnels."
Prison Architect is quickly becoming my most favorite game of 2013. I picked it up back in Alpha 13 and recently figured out how to build a sustainable prison. Introversion just dropped the new Alpha 14 update that added Dogs and the ability to sell your prison. These really add on to the game in important ways that I appreciate. Before, the only way to detect stuff was with a metal detector but that won't find drugs. Now you can have Dogs sniff out contraband and also be alerted about tunnels.
I can't wait to add the kennel to my prison and replace many of my guard patrols with dog handlers. I also think ill put a dog unit at the front of my prison to keep the escape attempts down as well. LONG LIVE DOG ARCHITECT!
http://forums.introversion.co.uk/viewtopic.php?f=17&t=44984

Their email update was a lot more sarky. Like this bit:
Enjoy it, Chris' wife is birthing another nipper so it's all you're going to get until December!
Yeah, they mentioned that in the video. Glad they are able to take time off, that stuff is important. I love the game, but yeah, live your life man.