I have a three year old female min pin that will go several months without peeing inside the house but then will start to pee on the furniture for a few weeks. She has repeated this cycle since we have had her (about 2 years). She spends a lot of time outside and will go to the bathroom outside but will then come in and pee on the couch. I have taken her to the vet thinking maybe it's a health problem but the vet says she is fine. I don't know what to do. I love her and don't want to get rid of her but my house smells urine. Does anyone have any ideas?