So, about deer...
How do deer get it? Well, many of the deer in the articles above were farm-raised (most deer meat you can buy is not wild hunted, folks!) and so had frequent contact with humans. And on farms, wild deer do often come by and interact with farmed deer through fences.
Also, wild deer do rummage through human trash - a deer getting into trash loaded with used tissues, and you have possible infection.
I'm surprised a lot of "house cats" wouldn't have similar problems, with the large number of them in the states that are let roam the neighborhoods, neighborhoods right next to large feral colonies (often moving from a bowl and one house to a bowl at another).
A zoo lost three snow leopards due to complications. Is there anything about cats that's vastly different from people that a symptomatic one wouldn't have it in their respiratory tract? (I know little enough of human anatomy let alone cat).A major point to make is that we do not know if these deer can pass it back to humans. These deer were not tested by nose-swab, so the data does not directly indicate presence in the upper respiratory tract, or what levels it is present there in the deer - the droplet-based transmission we see in human transmission may not be a thing for deer.