I think greater than dumb or smart (besides maybe orange cats, maybe they love trannies) its more animals are far more primal in nature. The whole idea of a huge subset of societal rules instilled in someone is kinda a requirement of trans bs to be accepted. Like even assume you generate a conciousness from nowhere, with decent intelligence and BASELINE understanding of the world. They will see a tranny and think "why is this man trying to look like a woman?"
So for animals trying to make them accept that shit is just a no, its like trying to make a cat NOT want to chase quick moving small things. You are a man, and they aren't going to think "oh gee wizz I mean thinking that might hurt xirs feelings so I better be nice", they don't have time for that....literally, cats live what, 13 years? thats your average teenager AT BEST, with also an incurable language barrier. So even trying to get this AS A CONCEPT to them is an immense challenge, much less accept and respect it.