"They sneeze at moments of high emotion."
Dogs are strange animals, at any rate until one truly imagines things from their point of view. Then they make very good sense. If they bark at passing trucks, it is because when one barks at approaching trucks, the trucks very obligingly take the hint and go away. Obedient creatures, really. If they shy away from strangers' hands, well, what makes you think any right-thinking person would be comfortable being pawed at by total strangers on the street? I wouldn't be. I might bark at them too, I might. I might even bite.
The sneezing, though. Prancing around in hopes of enticing me into play, he may sneeze explosively. Also at the prospect of going for a long-awaited walk. I laugh at him.
But I sneeze in bright sunlight. It's been explained to me as a short circuit. My visual receptors flash awake and fire a signal up my optic nerve, fair enough, but the nerve must in my case lie a little too close to my lowest sinuses. The electrochemical flare leaps and I feel it like obnoxious tickling pollen and I sneeze. The dog never laughs at me, busy tugging me down the stairs into the morning.
Something must be firing wildly in the head of a prancing dog, his heart so full of feeling, his brain overwhelmed with zooming pulses. Joy must tickle his nose.