10 years before I got my dog I had an accident in the army where I dislocated both ankles. I had surgery, pins/bolts put in and a few years of rehab. All my scars had healed, but I still had pain and instability in both feet.
When I got my dog, she was a pup. Yet at 1 year old she would sniff my lower legs, and lick not at the scars, but at where the pain in my ankles/feet were. She could seance where the problem was and tried to make it better. About 6 months later, she started jumping up on my mother, she knew not to jump up on anyone and was well trained, I was puzzled by this behavior.
A little while later it was discovered my mother had Breast Cancer, it was then that I found out why she was jumping up on my mother. After the operation was successful on my mother, and she was home, my dog no longer went to jump up on her.
Who is to say what animals can sense hey?