I have a big black Manx named Ozzy that used to be an ally cat, hes very attached to me and didnt like Leonard my boxer much at all when I first got him. I introduced the two outside on neutral territory, this helped ALOT. After the initial sniffing and what not I brought the puppy inside and put him in the bathroom and closed the door. This allowed Ozzy to get used to the dog being in the house while not being able to torment him. The cat sat in front of the door and hissed a few times but after a few hours lost interest. Next I put the puppy in his crate and left him the middle of the living room. Ozzy didn't like that all and much hissing and spitting ensued but once again, after some time, he got over it. To this day Ozzy only tolerates the dog and I if I raise my voice at the dog or clap (how I get Leonards attention) Ozzy come flying out of nowhere and attacks the dog, its the damnedest thing Ive ever seen. ANYWAY long story short, just take baby steps in introducing them and they should be OK.