Posted in Doghouse as well but trying here too as it's 50:50 dog/cat!
Any advice welcome!
We adopted a rescue cat yesterday (so yes, it's very early days). She is 1 and very sweet and affectionate - to humans!
What's the best way to try for a peaceful co-existence? We let them sniff at each other from behind a door and she's seen him with us holding him on a short lead. Within a couple of minutes of first seeing him she rushed forward and attacked - hissing, scratching - the works.
Today she's been in 'her' room for much of the day and then we let her explore some more of the house. Dog was outside and they saw each other through glass door. Cat then settled on sofa and I had dog on my lap. Then DH took dog out for a walk and when he came back into the house the cat literally streaked across the room to attack him again. I had to dash to grab her and I ended up scratches across my face in the process 
She's now in a large crate with bed, litter tray and I've been feeding her treats and dog at the same time. When the treats are flowing it seems fine but he then moved a bit and she went for him (but couldn't because of the crate which is the whole point I guess).
So...where do we go from here? Will she always hate him? Maybe she was once attacked by a dog and loathes them, and we just don't know as she's a rescue?
I'm so worried...then I tell myself it's only been just over 24hrs that she even arrived and I need to calm the f*%# down!!