I've been able to communicate through body language with animals. My friends cat is always jumpy and scared until I look him so he sees me and I make a friendly face. Also, animals are mostly fixated on our hands when they see us (because thats whats giving the food and petting them) so communicating your intentions with your hands is also important. I've never experianced a true conversation, like I would with a human, but there is definitly a palpable progression of familiarity when I try to communicate with animals. Most of it I think is just getting out of what you would like the animal to communicate, and just consciously observing.
