Nugget and them felines
My elderly black-and-tan dachshund -- Nugget "The Toothless Wonder" -- used to react to cats in weird ways (now always he feigns blindness):
If the cat showed it was scared, well! Nugget would start acting like a big shot (i.e. a fully-fanged doberman), barking and chasing (if necessary). Never got too close to the cat, though -- he's dumb, but ain't that dumb.
If the cat ignored him, Nugget figured it was out of his league, and would "save face" by ignoring it back. Though one time, he figured the not-running-away-cat must be a funny looking dog. So he went over and tried to sniff its butt -- which did not go over very well with the cat, believe me!
The last time he actually interacted with a cat was at the vet's office -- we used to go to a vet that had a rescue cat who "owned" the office. No fear of dogs, or strangers, or anything. It jumped up on the bench next to me while I had Nugget in my lap, and proceeded to ignore both of us.
Nugget sniffed it -- and then stood looking off into the distance, his gaze just above the cat's head, absolutely transfixed. The cat yawned and then decided to catch a nap. Nugget, meanwhile, was frozen in thought -- I could almost hear the gears in that dog's head click-click-click through the thought processes: "Hmmm, it's not a ... human, no, no, doesn't smell like one of them ... dog? hmmm . .. no, no, not quite a dog ... it ... must ... be ... wait a minute, wait a minute ... it's coming to me ... yes, not a dog, then ... ummm ... it's ... a ... c ...a ... t ... cat. Yup, cat ... I mean ... CAT!!!!!"
When the lightbulb went off in that little dachshund brain of his, Nugget knew exactly what he had to do: BITE ... THE ... CAT!!! And he suddenly lurched forward to grab the cat by the back of its neck!
I don't know who was more surprised -- me or that cat!
Or Nugget, for that matter!
Thank god Nugget isn't called "The Toothless Wonder" for nothing -- so he basically gave the cat a good one-grab gumming -- but still!
The cat ran away, and Nugget's doghood was restored.
BTW: When we left the office later, the cat stood by the door and neither one of those animals would give the other the satisfaction of a nod of acquaintance. It appears that both had become, suddenly, selectively blind.