I have a two yr old Pomeranian that has started using the inside of her house as a bathroom.  She has been trained to use a doggie door and has lots of room on my half acre of land to go do her business but recently, she has started doing her business inside her house.  She has only been doing this a little while and I would like to figure out the reason for the change in her behavior.  There have been no changes in her food, socialization (playing with me and the other dogs), water or temperature inside her house or out.  She A/C and heat in her house.  She is a delightful pet and I love her dearly but this is a real problem because she sleeps in her house.