Me and my husband are thinking of getting a puppy this year, but we are wondering if our two adult cats will be able to share their territory with the new puppy. It will be a pity to get the puppy and realize that our house has become a war zone for good! Any advise on how to introduce the puppy to the cats?

I am thinking of getting a puppy growing to be medium sized but the problem is no one is at home from 8 in the morning to 4 in the afternoon. What should I do to keep the puppy occupied? Should I leave it in a crate that long? My father may come at around noon to have lunch and take the puppy out to relieve itself. What should I do for the puppy during the 4 hours or so it is alone at home?