Hi, @snowmachine, lovely dogs! Looks like the black one enjoys playing with water while the lighter colored one doesn't?
Have you taken a look at research about how our gut flora affects our moods? Apparently there is a strong link between our moods and the mix of microbes that live in our guts. If you are interested, here is a short article from New York Times. https://www.nytimes.com/2015/06/28/magazine/can-the-bacteria-in-your-gut-explain-your-mood.html