What I am going to say will not surprise anyone who is a dog owner: presence of dogs inside a house makes for a more relaxed atmosphere. There are even documented benefits on psychical well being as well as on some objective health aspects, like blood pressure. Some dog breeds spread more relaxation than others: I had for many years a wonderful Golden Retriever, which was a champion in this domain, but it is probably difficult to beat a big St Bernard – both for the benevolent aspect and for the proverbial calmness.