I've always been amazed by how sensitive dogs are to the emotions and needs of human beings, but I never knew dogs could do this.  Guide dogs who assist war veterans are trained to identify when their owners are having nightmares and bad flashbacks and to wake up the veterans up to avoid them from having to relive the pain of war over and over again.  

It is truly touching to know this happens all over the world, and I'm honestly shocked that I've never learned this before.

[Updated 9/8/2014: author corrected terminology to say 'veterans' as opposed to 'ex-soldiers' with apologies to those offended, as well as their family and friends]