It seems that most pets can sense human emotions, especially when humans are nervous or frightened. Some can even smell fear because of our hormones. I have noticed that with dogs. My dog would sniff and bark even when we could not see what she was barking about.
I also ran across another neighbor's dogs who met me for the first time. One of them I was not comfortable around, and he started jumping at me without me saying a word. The other dog that I was ok with did not react, but she watched to see what was going on. After I mentioned how I felt to a witness, he told me that the other dog was reacting to my fear. I believed him and did everything I could to calm down. The dog finally left me alone.
