Originally Posted by Lucky Rescue
I've said "No" to my cats also. But that is very different than squirting with water a 10 year old cat who feels his territory has been invaded and is in aggression mode. A cat like this need redirection/distraction and not punishment.
This is just my personal opinion but there are two thing here. Cats don't get hurt when they get wet. Granted most cast will avoid getting wet, but squirting them won't hurt them and really shouldn't be considered cruel (having the dog take a piece out of the cat because its had enough of being pushed around, now that would be cruel and painful).
The other thing is, maybe there is a reason the cat is acting that way. Maybe the dog has hurt it or stolen a toy. Maybe the cat isn't getting enough attention or exercise... Maybe the cat prefers the dog's brand of food (my cat won't eat food that isn't made by the same company as the dog's food) or prefers the type of bed the dog has.
I like the idea of keeping them apart when you aren't around. And your room-mate will likely understand that work needs to be done so that everyone is happy. And like TenderFoot suggested, once your dog knows you'll handle all the rough stuff for it, the confidence will start to go up.