Help With Introducing Aggressive Dog and Cat

Quick background, I had a cat since I was 16 and when my wife and I bought our first house, we decided we wanted to get a dog as well. We rescued a 10 month Border Collie who really paid no attention to my cat in the beginning. Once she became comfortable, she would play with the cat (very non-aggressively) and they got along great. About a year later I had to put my cat down. We said we weren’t going to get another cat but about 6 months later we decided we wanted another one both for us and as a companion for our dog.

We got a kitten and brought him home and took the shelter’s recommendations of leaving the cat in one room for a week and slowly introducing him to the house. From the moment we brought the cat into the house, our dog would not leave the bedroom door that he stayed in. Our dog no longer wanted to see us, play, or do anything besides stand outside that door. After a week or so we opened up the door and put up a gate so that they could see each other. Every time the cat would go near the gate the dog would lunge at it and scare the cat away. After another week or so we put the dog on a leash and brought the cat out so that they could sniff each other a little. As soon as the dog gets anywhere near the cat she lunges at him and tries to bite him. In talking to our vet, she said that she usually just introduces animals by putting them in a room together, however if the dog is already showing signs of trying to bite, then that probably isn’t the best idea. What we have been doing for the past month or so is to have them in the same room together every day, but keep the dog on a leash so that she cannot get to the cat. We also bought a muzzle for the dog but then when she gets close to the cat she tries swiping with her paws. The other problem is that the cat does not want to defend himself. If the dog comes over to him he will hiss but does not try to swipe or bite the dog.

We kept thinking eventually they would get better with each other, but we are now at the point where the cat does not want to stay in his room any longer, and therefore constantly jumps over the gate. As soon as the dog sees him we have to act quickly before he gets attacked. We now have to keep the cats door closed when we are not around and when we go to sleep, which I feel really bad about. Has anyone had any experiences such as this? Are there any other ideas of things we can try or is this pretty much going to be the best it’s going to get? I want my cat to be able to enjoy the whole house and for my dog to return to how she used to be, and actually care about anything besides standing outside the cat’s door. The only thing I can think of as to why she is acting so differently with this cat is that the other cat was in the house before her. With the new cat, the cat is coming into ‘her’ house.

Sorry for the long post, we are just running out of ideas and getting frustrated with the situation. Can’t they all just get along :/