You could always opt for rescue dog that gets along with cats. It will be a change for everyone. Are your cats the type that hold grudges? or do they frequently have behaviors (like not using the litter box) when they are stressed? If so be prepared for that. Take introductions VERY slowly. Allow everyone to sniff through a closed door. See if you can have the dog stay in a room that will be his for a bit so he has a place without the cats. Take the dog out after a while, put the cats in. They'll be sniffing each others scents.
I would start actual introductions one at a time.. If you've got a frendlier cat, do that one first. Don't leave them alone unsupervised until you are sure everyone is ok.
A puppy is a good choice, just keep in mind puppies learn and grow at different rates, and what if 4 months isn't enough? Or what if the puppy will not overcome the prey drive and terrorizes the cats? Its all stuff to think about.
Dogs and cats have lived together successfully for ever. We're planning on adding a dog to our two-cat household at some point in the future.
Also, keep in mind the personalities of the breeds you are choosing. Huskies tend to be VERY headstrong, high energy and stubborn. Gsheps are incredibly smart and need an outlet for that intelligence. Pibblies are very smart and very eager to please, just PLEASE don't get one from a back yard breeder.. There are so many of these guys in shelters
Good luck though, keep us updated
