Do animals sense/act differently around psychopaths?
My ex was also a Narcissist and undoubtedly pretty high on the psychopathy scale. We got a dog together and no matter how hard I tried to train him something was always off. He was leash aggressive and extremely protective. I spent a lot of money on training and it made a minor difference but he would literally revert back a few weeks after training was complete. Just to clarify although he was my first dog I have a 10+ year background in education so I wasn't completely clueless. The dog never really got to spend too much time with him as he was also a workaholic and would come home relatively late.
I never really thought much of it until one trainer told me that dogs are essentially an emotional barometer for those that they are attached to. Something clicked and I started noticing that after spending time wish the X the dog's behaviour was worsened. Keep in mind we got the dog together so he was "our dog" - mind you he never really did much more than complained when the dog destroyed something and kinda cuddle with him.
Things ended as sour as possible as it often does with narcissist - like borderline WW3. He said he wanted visitation with the dog I said NO WAY IN HELL as he had almost killed the dog previously twice because of neglect. He said I'll see you in court; luckily he found himself another victim and left us alone and never bothered to fight for the dog.
Anyhow, it's been two years and the dog is a completely different dog. Everyone that knew him previously say the same thing :-) I honestly believe animals have a "sixth" sense when it comes to humans and I trust his judgement better than mine. Mind you he was already an adult when things ended.
To answer your question I truly believe dogs know and will act differently with certain personality types. I also believe that internally we know when something is off and the dogs sense our aversion to someone before we even sense it.