Speaking from someone who has socialized many cats, bringing in a new can be a process and not something that happens overnight. If you decided to try again you may need to keep the old cat isolated and do a slow introduction with limited roam space for them all.
I am not sure if the dog should be in the mix yet, let the cats start showing some love towards each other. You know your cats may never be best friends, they may just learn to tolerate each other but that is okay as long as there is no blood loss in the deal.
__________________ Cheryl,Mom to  SophieKate |