Thats a great story!
I'm amazed at what Murphy can smell.
I was on the trail a couple weeks ago and we stopped by a bridge to rest for a bit. I watched him tracking and, after a minute realized that he was tracking an ant. Following the same path with his nose that the ant had just made.
On occasion I have a little knee pain in my left knee. Nothing major, just an ache slightly right of the knee cap. When it acts up I notice Murphy, when he is in my lap, will sniff exactly on the sore area.
Their noses are amazing. I often wonder what the world must smell like when we're walking.