I have an 8 year old lab mix who has been going to the bathroom in the house more & more often over the course of the past year. Up to about a year ago, she NEVER went in the house -- then she came down with a case of giardia last spring, which caused severe diarrhea and several occasions of 

ooping and peeing in the house. Our vet treated her thoroughly and pronounced her cured early last summer.
I'm wondering if somehow that experience caused her to think it's ok to go in the house?? Any thoughts? If it's not that, any other ideas of what could be causing it? We've ruled out physical issues with our vet.
I'd greatly appreciate any help -- we live in Minnesota, where keeping a dog outside is NOT an option, and she's the love of our lives -- but we can't live with a dog that uses the living room as her own personal bathroom!