Is there a connection between not using the –ה and not interpreting a copula there? Couldn't it be "cats are against dogs"?
I wonder about the same because i think "cats are against dogs" have a different meaning than "cats against dogs". I think the latter could be said for instance if watching a political debate between two parties and then meant figurativly, the first sounds more like a general statement. Maybe it is impossible to know how to translate it without a context?