It's interesting that you got the information from a vet's office. Mothballs are toxic. I guess it is because you are using such a small amount and putting them deep into the carpet?
Be very careful she doesn't ingest any of it and store them somewhere safe.
I would feel better with the vinegar but I admit I am a worrier.
Here's what the EPA has to say about mothballs...
http://www.purdue.edu/dp/envirosoft/...e/mothball.htm
Congratulations on getting your first yorkie!!!! Aren't they the best?
