Step one to learn about black and white dog's you must have a source to a certain food. Ectoplasm a gross food indeed, it's ghost poop and you'll need it to get it you need to memorialize a dog core in a spooky room.then wait for a ghost to show up feed it a french fry then wait until you see a green slop in the ghost's body. Banish it then have the dog you want eat it.

Now that you know Ectoplasm let's see Ectoplasm! There will be something new in your friends gut and the more of that stuff the more black and white it will be when it pupate's!

Now that your dog is a adult you can take its code make a double and breed them to have pup's and continue the cycle!