My dog usually lies calmly in the back of the car on trips. This morning she sat upright in the passenger seat, staring at me and bumping me with her cold nose. Pretty sure it was because she sensed my nerves at being on the way to a double root canal. But I hadn't noticed it. Now I have to look at my dog to find out how I'm feeling.
Dogs are like small children that way. They are like lightning conductors for human emotions. They may not understand what's going on, but they can pick up on it.