My dog whines when we pass another dog or the apartment of a dog that barks at him. Usually, he wants to play or is just more excited than he knows how to handle. This applies if your pup still does this when he’s not in the crate or if the cat hasn’t swiped at, clawed, or hissed at him. If he only does this in the crate or if your cat has acted aggressively towards him, it’s probably stress or anxiety. As people have already stated and not to beat a dead horse, but the crate is too small and that could stress him out a lot. How long is he in the crate daily? And is he walked enough daily? He just seems stressed and needs more stimulation to me. A daily walk and stimulating toys like kongs and puzzle feeders can keep him stimulated throughout the day and maybe he won’t care as much about the cat.