We own a dog. She’s a wonderful pet that has had an enormously positive impact on the children. However, if anyone is considering getting a dog, do not underestimate the effort and cost of taking care of it properly. It’s a big responsibility.
The main halachic difficulty is shabbos. Being muktze does not mean that you can’t take care of the dog on shabbos, but one must be careful.
Rabbi Howard Jachter wrote a good summary of the halachos of owning pet. It’s worth reading. (Google it.)